WorldWideScience

Sample records for astron

  1. Observatorio Astronómico Nacional, Colombia

    Science.gov (United States)

    Murdin, P.

    2000-11-01

    The Observatorio Astronómico Nacional (OAN) was founded by José Celestino Mutis in the framework of the `Expedicion Botanica' on 20 August 1803. His first astronomer was Francisco Jose de Caldas. By the turn of the century, Julio Garavito worked in celestial mechanics—a crater on the far side of the Moon bears his name....

  2. Gravitational redshift experiment on RadioAstron

    Science.gov (United States)

    Litvinov, Dmitry; Bietenholz, Michael; Rudenko, Valentin; Biriukov, Alexander; Kauts, Vladimir; Kulagin, Victor; Bartel, Norbert; Gwinn, Carl; Cannon, Wayne

    The RadioAstron space radio telescope offers a possibility for testing the gravitational redshift effect with an accuracy of better than 10(-5) , thus, improving the result of the Gravity Probe A mission by at least an order of magnitude. However, RadioAstron’s communications and frequency transfer system doesn’t allow for a direct application of the nonrelativistic Doppler and tropospheric compensation scheme used in the Gravity Probe A experiment. This results in a degradation of the redshift test accuracy to approximately 1%. We discuss two approaches to overcome this difficulty and present preliminary results based on data obtained during special observing sessions scheduled for testing the new techniques.

  3. Observatorio Astronómico De Cantabria

    Science.gov (United States)

    Domínguez, R. M.; Carrera, F. J.

    The Astronomical Observatory of Cantabria is a center of the Consejería de Medio Ambiente del Gobierno de Cantabria managed by the Centro de Investigación del Medio Ambiente (CIMA), an autonomous organism which depends on such Consejería. The development of different activities of the Observatory is a joint collaboration between the University of Cantabria and the Agrupación Astronómica Cántabra (AstroCantabria). As part of the University of Cantabria, the Instituto de Física de Cantabria (IFCA, CSIC-UC) is in charge of the direction, management and coordination of scientific, observational, educational and outreach activities of the Observatory. AstroCantabria takes care of the outreach activities for the general public as well as the astronomical observations. In addition, it is responsible for the calibration and maintenance of the astronomical instrumentation of the Observatory. The Astronomical Observatory of Cantabria is located on the Southern edge of the Comunidad Autónoma de Cantabria, on the high plateau of La Lora (Valderredible county), at an altitude of 1,080m, with longitude 3∘ 56 ' 36' W and latitude 42∘ 46 ' 18' N. Rocamundo is the closest town. The Observatory aims to become a center of reference for scientific, observational, educational and public outreach activities in Cantabria. In the near future, an observational proposal system for outside users will be set in place.

  4. Alfabetización astronómica

    Science.gov (United States)

    Tignanelli, H.

    A fines de 1991, en una revista de educación en ciencias, José L. Sérsic reflexionaba acerca de los problemas que enfrentaría la enseñanza de los conocimientos astronómicos en nuestro país, en los umbrales del Siglo XXI. Entonces postulaba como un objetivo mínimo, que los jóvenes deberían mostrar signos claros de que se hallan astronómicamente alfabetizados. Era el año en que se realizaba por primera vez una Asamblea General de I.A.U. en Buenos Aires, una oportunidad de singulares características para la comunidad astronómica local y, simultáneamente el comienzo de un cambio radical en la estructura del sistema educativo argentino. ?`Contempla ese cambio el objetivo que postulara Sérsic? ?`Estamos en condiciones de afirmar que estamos en camino de lograrlo? ?`Con qué parámetros?. Presentamos aquí un panorama general sobre algunas de las acciones realizadas en función de alcanzar esa alfabetización científica, analizando exclusivamente la actividad de enseñanza hasta el nivel universitario, sin detenernos en el mismo, ya que lo consideramos una instancia superior e independiente de aquella alfabetización. Tampoco nos referiremos a la tarea de difusión, divulgación o popularización de la Astronomía, ya que su condición de asistemática y subjetiva no es evaluable en términos de la formación integral de un individuo.

  5. RadioAstron gravitational redshift experiment: status update

    CERN Document Server

    Litvinov, D A; Bartel, N; Belousov, K G; Bietenholz, M; Biriukov, A V; Cimo, G; Duev, D A; Gurvits, L I; Gusev, A V; Haas, R; Kauts, V L; Kanevsky, B Z; Kovalenko, A V; Kronschnabl, G; Kulagin, V V; Lindqvist, M; Calves, G Molera; Neidhardt, A; Ploetz, C; Pogrebenko, S V; Porayko, N K; Rudenko, V N; Smirnov, A I; Sokolovsky, K V; Stepanyants, V A; Yang, J; Zakhvatkin, M V

    2016-01-01

    A test of a cornerstone of general relativity, the gravitational redshift effect, is currently being conducted with the RadioAstron spacecraft, which is on a highly eccentric orbit around Earth. Using ground radio telescopes to record the spacecraft signal, synchronized to its ultra-stable on-board H-maser, we can probe the varying flow of time on board with unprecedented accuracy. The observations performed so far, currently being analyzed, have already allowed us to measure the effect with a relative accuracy of $4\\times10^{-4}$. We expect to reach $2.5\\times10^{-5}$ with additional observations in 2016, an improvement of almost a magnitude over the 40-year old result of the GP-A mission.

  6. SPECKLE INTERFEROMETRY AT THE OBSERVATORIO ASTRON ́ OMICO NACIONAL. VI.

    Directory of Open Access Journals (Sweden)

    V. G. Orlov

    2015-01-01

    Full Text Available Presentamos mediciones de estrellas dobles mediante interferometría de motas, obtenidas en agosto de 2010 con el telescopio de 1.5 m y en mayo de 2010 con el telescopio de 2.1 m del Observatorio Astronómico Nacional en SPM (México. Reportamos los resultados de 331 mediciones de 321 sistemas, con una magnitud límite para las primarias de V = 12.9. Las separaciones angulares medidas están comprendidas entre 0.13 y 7.39 segundos de arco. 269 pares resultaron tener separaciones de menos de 1 segundo de arco. El error medio en las separaciones es de 0.032 segundos de arco, y en los ángulos de posición, 2 grados. La ambigüedad usual de 180 grados en los ángulos de posición fue corregida para la mayoría de ellos usando observaciones de otros autores.

  7. Measurement of the gravitational redshift effect with RadioAstron satellite

    CERN Document Server

    Birukov, A V; Litvinov, D A; Porayko, N K; Rudenko, V N

    2015-01-01

    RadioAstron satellite admits in principle a testing the gravitational redshift effect with an accuracy of better than $10^{-5}$. It would surpass the result of Gravity Probe A mission at least an order of magnitude. However, RadioAstron's communications and frequency transfer systems are not adapted for a direct application of the non relativistic Doppler and troposphere compensation scheme used in the Gravity Probe A experiment. This leads to degradation of the redshift test accuracy approximately to the level 0.01. We discuss the way to overcome this difficulty and present preliminary results based on data obtained during special observing sessions scheduled for testing the new techniques.

  8. Historia de la Ciencia árabe: los sitemas astronómicos

    OpenAIRE

    Torroja, J. M.

    1981-01-01

    En un curso de conferencias sobre Historia de la Ciencia Árabe no podía faltar una sobre sus ideas acerca de los sistemas astronómicos, que tanta importancia tuvieron a lo largo de los siglos en la cultura árabe, primero en Oriente y más tarde en España, bajo el mecenazgo de los Califas de Bagdad y de Córdoba. Esta ciencia astronómica árabe sería recogida por Alfonso el Sabio en sus Libros del Saber de Astronomía y pasaría a Europa a través de las traducciones efectuadas tanto en las escue...

  9. VIII Olimpíada Brasileira de Astronomia e Astronáutica

    Science.gov (United States)

    Garcia Canalle, João Batista; Villas da Rocha, Jaime Fernando; Wuensche de Souza, Carlos Alexandre; Pereira Ortiz, Roberto; Aguilera, Nuricel Villalonga; Padilha, Maria De Fátima Catta Preta; Pessoa Filho, José Bezerra; Soares Rodrigues, Ivette Maria

    2007-07-01

    Neste trabalho apresentamos as motivações pelas quais organizamos, em conjunto, pela primeira vez, a Olimpíada Brasileira de Astronomia incluindo a Astronáutica, em colaboração com a Agência Espacial Brasileira. Esta ampliação contribuiu para atrair ainda mais alunos, professores, escolas e patrocinadores para participarem desta Olimpíada. Em 2005 participaram da VIII Olimpíada Brasileira de Astronomia e Astronáutica (VIII OBA) 187.726 alunos distribuídos por 3.229 escolas, pertencentes a todos os estados brasileiros, incluindo o Distrito Federal. O crescimento em número de alunos participantes foi 52,4% maior do que em 2004. Em abril de 2005 organizamos, em Itapecerica da Serra, SP, um curso para os 50 alunos previamente selecionados e participantes da VII OBA e ao final selecionamos, dentre eles, uma equipe de 5 alunos, os quais representaram o Brasil na X Olimpíada Internacional de Astronomia, na China, em outubro de 2005. Ganhamos, pela primeira vez, uma medalha de ouro naquele evento. Em Agosto de 2005, organizamos a VIII Escola de Agosto para 50 alunos e respectivos professores, em Águas de Lindóia, SP, juntamente com a XXXI reunião anual da Sociedade Astronômica Brasileira (SAB). Em novembro de 2005 realizamos a I Jornada Espacial, em São José dos Campos, com 22 alunos e 22 professores selecionados dentre os participantes que melhores resultados obtiveram nas questões de Astronáutica da VIII OBA. Neste trabalho detalhamos os resultados da VIII OBA bem como as ações subseqüentes.

  10. The Nuclear Structure of 3C84 with Space VLBI (RadioAstron) Observations

    CERN Document Server

    Giovannini, Gabriele; Savolainen, Tuomas; Nagai, Hiroshi; Giroletti, Marcello; Hada, Kazuhiro; Bruni, Gabriele; Hodgson, Jeffrey; Honma, Mareki; Kino, Motoki; Kovalev, Yuri Y; Krichbaum, Thomas; Lee, Sang-Sung; Lobanov, Andrei; Sohn, Bong Won; Sokolovsky, Kirill; Voitsik, Peter; Zensus, J Anton

    2015-01-01

    The radio galaxy 3C84 is a representative of gamma-ray-bright misaligned active galactic nuclei (AGN) and one of the best laboratories to study the radio properties of subparsec scale jets. We discuss here the past and present activity of the nuclear region within the central 1pc and the properties of subparsec-sized components C1, C2 and C3. We compare these results with the high resolution space-VLBI image at 5GHz obtained with the RadioAstron satellite and we shortly discuss the possible correlation of radio emission with the gamma-ray emission.

  11. Extreme Brightness Temperatures and Refractive Substructure in 3C273 with RadioAstron

    CERN Document Server

    Johnson, Michael D; Gwinn, Carl R; Gurvits, Leonid I; Narayan, Ramesh; Macquart, Jean-Pierre; Jauncey, David L; Voitsik, Peter A; Anderson, James M; Sokolovsky, Kirill V; Lisakov, Mikhail M

    2016-01-01

    Earth-space interferometry with RadioAstron provides the highest direct angular resolution ever achieved in astronomy at any wavelength. RadioAstron detections of the classic quasar 3C273 on interferometric baselines up to 171,000 km suggest brightness temperatures exceeding expected limits from the "inverse-Compton catastrophe" by two orders of magnitude. We show that at 18 cm, these estimates most probably arise from refractive substructure introduced by scattering in the interstellar medium. We use the scattering properties to estimate an intrinsic brightness temperature of 7*10^12 K, which is consistent with expected theoretical limits, but which is ~15 times lower than estimates that neglect substructure. At 6 cm, the substructure influences the measured values appreciably but gives an estimated brightness temperature that is comparable to models that do not account for the substructure. At 1.3 cm, the substructure does not affect the extremely high inferred brightness temperatures, in excess of 10^13 K....

  12. Practical Astronomical Activities during Daytime. (Spanish Title: Actividades Astronómicas Prácticas Diurnas.) Atividades Astronômicas Práticas Diurnas

    Science.gov (United States)

    Jackson, Eric

    2009-12-01

    These daytime astronomy activities arose from research done in New Zealand by a group of teachers and astronomers into the problems of teaching astronomy. This showed that it was generally regarded as a difficult subject to take, traditionally relying on books, films and models. The fortunate may have had a visit to an observatory or planetarium, the adventurous may have attempted an outdoor evening viewing session, which sometimes had weather-related difficulties. The problem of not having many 'hands-on' activities, the feelings of inadequate knowledge, the felt need for astronomical equipment and expertise become too daunting for many teachers to do the subject justice. If astronomy was to be taught then a way around these difficulties needed to be found. Our group, working with teachers and children using the constructivism teaching approach, found that the principles of astronomy could be discovered during the day when the students are at school. Working co-operatively they measured and recorded observations of their shadows caused by the motions and interactions of the nearest star, the Sun (Sol), and our planet, Earth. Because children were involved so personally they were much more interested in the results of the study. Astronomy became enthralling and challenging for both teacher and class after applying their daytime experiences to night time viewing at home and reporting back to class. Estas actividades astronómicas diurnas surgieron de una investigación hecha en NuevaZelandia por un grupo de maestros y astrónomos sobre los problemas de la enseñanza de la Astronomía. Este trabajo mostró que la Astronomía es generalmente considerada una disciplina difícil de enseñar, y tradicionalmente basada en libros, filmes y modelos. Los más afortunados pueden haber efectuado alguna visita a un observatorio o planetario, y los más aventajados pueden tal vez haber intentado una sesión de observación nocturna, las cuales sufren a veces de dificultades

  13. Model for the coma of Comet Halley, based on the Astron ultraviolet spectrophotometry

    International Nuclear Information System (INIS)

    The development of a model of the Comet Halley coma from spectral and photometric data is described. Spectra in the 1500-3500 A range and photometric scans at the 3085 A and 2190 A in the (0-0) band of the OH and CO(+) molecules were obtained by the UV telescope of the satellite Astron on December 3, 13, and 23, 1985. Surface-brightness profiles of the coma in the (0-0) band of OH, NH, and CS molecules are derived. The source and formation of these molecules, the lifetime of their radicals, the radial velocity of their parent molecules, and the water-molecule sublimation rate are computed and examined. The basic characteristics of the comet observed from the UV data are compared to the properties of other comets. It is observed that Comet Halley is similar to other large short-period comets. 29 references

  14. Space-VLBI with RadioAstron: new correlator capabilities at MPIfR

    CERN Document Server

    Bruni, G; Alef, W; Lobanov, A; Zensus, J A

    2015-01-01

    DiFX is a correlator for VLBI data based on the FX architecture (first Fourier transform and then cross-multiply). DiFX is a free licensed software written in C++, developed and maintened by an international group of programmers. A new DiFX version (dra) has been developed at Max-Planck-Institut f\\"ur Radioastronomie (MPIfR), in order to manage the correlation of a space-based antenna with ground stations. The dra version is running on the High Performance Computer cluster (HPC) in Bonn, and it is used for the data processing of the three AGN imaging RadioAstron Key Science Projects ongoing, based at the MPIfR.

  15. Observações de planetas extrasolares no Observatório Astronómico da Ribeira Grande (Fronteira)

    OpenAIRE

    Pereira Santos, N.P.; Bezzeghoud, M.; Caldeira, B.; Santos, N.C.; Santana, M

    2012-01-01

    O estudo dos planetas extra-solares tem sido uma das áreas em maior actividade na Astronomia e inclusivamente tem impulsionado estudos em áreas como a Geofísica, para uma melhor compreensão da origem e evolução dos planetas. O projecto TRANSIT, do Centro de Geofísica de Évora, desenvolve uma campanha de acompanhamento de trânsitos de planetas extra-solares, utilizando o Observatório Astronómico da Ribeira Grande (Fronteira), cujos resultados apresentamos neste trabalho. Este tipo de campan...

  16. Determinación astronómica de la Desviación de la Vertical

    Science.gov (United States)

    Pacheco, A. M.; Podestá, R. C.

    A partir de las coordenadas astronómicas de Latitud y Longitud determinadas en la falla geológica de Nikizanga ubicada en las serranías de Pie de Palo, y, en base a un Punto Datum de referencia, se desarrolla la metodología para la determinación de la Desviación de la Vertical, que comprende la reducción de las observaciones astronómicas, transformaciones de coordenadas, aplicación de correcciones y el cálculo definitivo de los valores angulares de la Vertical. Estos estudios se iniciaron a sugerencia del Servicio Internacional de Latitud, International Polar Motion Service (IPMS), con el objeto de obtener en determinados puntos de la Tierra la Desviación de la Vertical y su variación, dentro de la nueva disciplina denominada Astrogeodinámica, con la idea de correlacionar estas variaciones con la predicción de grandes sismos.

  17. RadioAstron -- a Telescope with a Size of 300 000 km: Main Parameters and First Observational Results

    CERN Document Server

    Kardashev, N S; 10.1134/S1063772913030025

    2013-01-01

    The Russian Academy of Sciences and Federal Space Agency, together with the participation of many international organizations, worked toward the launch of the RadioAstron orbiting space observatory with its onboard 10-m reflector radio telescope from the Baikonur cosmodrome on July 18, 2011. Together with some of the largest ground-based radio telescopes and a set of stations for tracking, collecting, and reducing the data obtained, this space radio telescope forms a multi-antenna ground-space radio interferometer with extremely long baselines, making it possible for the first time to study various objects in the Universe with angular resolutions a million times better than is possible with the human eye. The project is targeted at systematic studies of compact radio-emitting sources and their dynamics. Objects to be studied include supermassive black holes, accretion disks, and relativistic jets in active galactic nuclei, stellar-mass black holes, neutron stars and hypothetical quark stars, regions of format...

  18. Recuperación de información astronómica : nuevas perspectivas de análisis de la cartografía celeste histórica

    OpenAIRE

    Alonso Lifante, María Pilar

    2014-01-01

    La mejora de la descripción de contenidos de recursos especializados en general, y de astronómicos en particular, es todavía una asignatura pendiente de las Ciencias de la Documentación. Actualmente existe gran cantidad de información astronómica histórica de interés recogida en diversos tipos de documentos que se conservan en archivos y bibliotecas astronómicas de todo el mundo. Entre estos documentos se encuentran los denominados catálogos y atlas de estrellas, así como imágenes astrofotogr...

  19. Parque Astronómico de Atacama: An Ideal Site for Millimeter, Submillimeter, and Mid-Infrared Astronomy

    Science.gov (United States)

    Bustos, R.; Rubio, M.; Otárola, A.; Nagar, N.

    2014-12-01

    The area of Chajnantor, at more than 5000 m altitude in northern Chile, offers unique atmospheric and operational conditions which arguably make it the best site in the world for millimeter, submillimeter, and mid-infrared observatories. Long-term monitoring of the precipitable water vapor (PWV) column on the Chajnantor plateau has shown its extreme dryness with annual median values of 1.1 mm. Simultaneous measurements of PWV on the Chajnantor plateau (5050 m) and on Cerro Chajnantor (5612 m) show that the latter is around 36% lower under normal atmospheric conditions and up to 80% lower than the plateau in the presence of temperature inversion layers. Recently, the Government of Chile has consolidated the creation of the Parque Astronómico de Atacama (Atacama Astronomical Park), an initiative of the Chilean Commission for Science and Technology (CONICYT). This new park offers an opportunity for national and international projects to settle within its boundaries, gain access to an extremely dry site that is suitable for observations over a broad spectral range, especially in the millimeter to mid-infrared wavelengths, and benefit from operational and logistical support within a secure legal framework.

  20. Parque Astron\\'omico de Atacama: An ideal site for millimeter, sub-millimeter, and mid-infrared astronomy

    CERN Document Server

    Bustos, Ricardo; Otárola, Angel; Nagar, Neil

    2014-01-01

    The area of Chajnantor, at more than 5000 meters altitude in northern Chile, offers unique atmospheric and operational conditions which arguably make it the best site in the world for millimeter, sub-millimeter, and mid-infrared observatories. Long-term monitoring of the precipitable water vapor (PWV) column on the Chajnantor plateau has shown its extreme dryness with annual median values of 1.1 mm. Simultaneous measurements of PWV on the Chajnantor plateau (5050 m) and on Cerro Chajnantor (5612 m) show that the latter is around 36% lower under normal atmospheric conditions and up to 80% lower than the plateau in the presence of temperature inversion layers. Recently, the Government of Chile has consolidated the creation of the Parque Astron\\'omico de Atacama (Atacama Astronomical Park), an initiative of the Chilean Commission for Science and Technology (CONICYT). This new Parque offers an opportunity for national and international projects to settle within its boundaries, gain access to an extremely dry site...

  1. El «Plan de las inmediaciones» del Observatorio Astronómico: Un Proyecto desaparecido de Juan de Villanueva

    Directory of Open Access Journals (Sweden)

    Laca Menéndez de Luarca, Luis Ramón

    1999-09-01

    Full Text Available This paper reconstructs the "plan de las inmediaciones" ("project for the surroundings" hypothetically composed by Juan de Villanueva for Madrid Observatorio Astronómico, today disappeared. The data emanated from the drawing dedied to the Observatorio by Isidro Velazquez, Villanueva's best disciple, as well as from the parcel, allow to draw the perfect integration between the building and the surrounding landscape. Because of a number of circumstances two important elements are losten, the original access building and the great 25 feet telescope. Nevertheless, the restoration of the scene conceived by Villanueva, and later drawn by Velazquez, is still perfectly possible.No disponible

  2. Escuela de literatura i filosofía. programa de jeografía astronómica, física i política

    OpenAIRE

    Pinzón, José Rafael

    2009-01-01

    Nociones preliminares de geometría, necesarias para el estudio de la geografía.Geografía astronómica: Parte histórica; Parte científica; Aspectos del cielo; Estrellas fijas; Distancia de los planetas; Planetas; Planetas superiores; Planetas telescópicos que se encuentran entre Marte y Júpiter: Juno, Céres, Pálas, Vesta; Júpiter y sus satélites; Saturno, sus satélites y anillos; Herschell o Urano y sus satélites; Leverrier o Neptuno; Leyes de Kepler; Atracción universal; Masas planetarias; La ...

  3. Probing the innermost regions of AGN jets and their magnetic fields with RadioAstron. I. Imaging BL Lacertae at 21 microarcsecond resolution

    CERN Document Server

    Gómez, José L; Bruni, Gabriele; Kovalev, Yuri Y; Marscher, Alan P; Jorstad, Svetlana G; Mizuno, Yosuke; Bach, Uwe; Sokolovsky, Kirill V; Anderson, James M; Galindo, Pablo; Kardashev, Nikolay S; Lisakov, Mikhail M

    2016-01-01

    We present the first polarimetric space VLBI imaging observations at 22 GHz. BL Lacertae was observed in 2013 November 10 with the RadioAstron space VLBI mission, including a ground array of 15 radio telescopes. The instrumental polarization of the space radio telescope is found to be within 9%, demonstrating the polarimetric imaging capabilities of RadioAstron at 22 GHz. Ground-space fringes were obtained up to a projected baseline distance of 7.9 Earth's diameters in length, allowing us to image the jet in BL Lacertae with a maximum angular resolution of 21 $\\mu$as, the highest achieved to date. We find evidence for emission upstream of the radio core, which may correspond to a recollimation shock at about 40 $\\mu$as from the jet apex, in a pattern that includes other recollimation shocks at approximately 100 $\\mu$as and 250 $\\mu$as from the jet apex. Polarized emission is detected in two components within the innermost 0.5 mas from the core, as well as in some knots 3 mas downstream. Faraday rotation analy...

  4. Cálcul estructural d'un Observatori Astronómic situat a La Palma (Canàries), segons Normativa ENV 1993-1-1

    OpenAIRE

    Lacroizette i Mañas, Xavier

    2004-01-01

    Premi al millor Projecte de Fi de Carrera presentat durant el curs 2004-2005 en l'àmbit de Construcció que atorga el GREMI DE CONSTRUCTORS D'OBRES El present Projecte de Fi de Carrera està dedicat al disseny i càlcul estructural d’un dels complexes que composen l’Observatori Astronòmic del "Roque de los Muchachos", situat a la illa de la Palma (Canàries). Els diferents càlculs de la estructura metàl·lica s’han realitzat segons la normativa experimental europea ENV 1993-1-1, més coneg...

  5. The Fabra-ROA Baker-Nunn Camera at Observatori Astron\\`omic del Montsec: a wide-field imaging facility for exoplanet transit detection

    CERN Document Server

    Fors, O; Muiños, J L; Montojo, F J; Baena, R; Merino, M; Morcillo, R; Blanco, V

    2009-01-01

    A number of Baker-Nunn Camera (BNC) were manufactured by Smithsonian Institution during the 60s as optical tracking systems for artificial satellites with optimal optical and mechanical specifications. One of them was installed at the Real Instituto y Observatorio de la Armada (ROA). We have conducted a profound refurbishment project of the telescope to be installed at Observatori Astron\\`omic del Montsec (OAdM). As a result, the BNC offers the largest combination of a huge FOV (4.4$\\deg$x4.4$\\deg$) and aperture (leading to a limiting magnitude of V$\\sim$20). These specifications, together with their remote and robotic natures, allows this instrument to face an observational program of exoplanets detection by means of transit technique with high signal-to-noise ratio in the appropiate magnitude range.

  6. A Influência da Escola e da Mídia na Obtenção dos Conhecimentos Astronômicos

    Science.gov (United States)

    da Cunha, W. S.; Voelzke, M. R.; Amaral, L. H.

    2006-08-01

    O universo em que vivemos possui segredos jamais imaginados pelo homem, fruto da pequena proporção que ocupamos diante de um cosmos infinito. A astronomia funciona como um instrumento que sacia a sede humana em desvendar esses segredos, estudando as galáxias, quasares, pulsares além da existência de todos os elementos que preenchem o espaço cósmico, o vácuo, não mais vazio como se pensou em outros tempos. A mídia explora esse campo de forma mística e também científica. A difusão adequada e dentro dos padrões educacionais vigentes, de conceitos astronômicos, se faz necessária, devido sua presença nos conteúdos escolares, centros de ciência e na mídia, de modo geral. A reforma do Currículo Básico da Escola Pública da maioria dos Estados brasileiros introduziu conceitos astronômicos desde a pré-escola até o Ensino Médio. Num estudo realizado com 1.032 alunos do Ensino Médio de seis escolas estaduais, revelou-se através da aplicação de um questionário que abordava conheciment os básicos em astronomia, como estes foram adquiridos e qual era a infra-estrutura oferecida pela escola: para 66,2% dos entrevistados o professor já fez alguma apresentação a respeito de astronomia. O presente estudo revelou também que 44,5% dos alunos entrevistados adquiriram seus conhecimentos astronômicos na escola, 28,1% através da televisão e 27,4% afirmaram que seus conhecimentos foram obtidos através de outros tipos de mídia (internet, filmes e revistas). Embora o estudo revele claramente que há certo equilíbrio na forma em que os alunos obtiveram seus conhecimentos astronômicos, a mídia ainda explora e muitas vezes desperta o interesse pela astronomia com assuntos que não fazem parte de nosso cotidiano como, por exemplo, o homem na Lua, os projetos espaciais e a primeira viagem de um astronauta brasileiro no espaço. Porém, em certos casos, a mídia pode promover conhecimentos incompletos ou mesmo equivocados sobre os conceitos que envolvam

  7. PSR B0329+54: Substructure in the scatter-broadened image discovered with RadioAstron on baselines up to 330,000 km

    CERN Document Server

    Popov, M V; Gwinn, C R; Johnson, M D; Andrianov, A; Fadeev, E; Joshi, B C; Kardashev, N S; Karuppusamy, R; Kovalev, Y Y; Kramer, M; Rudnitskiy, A; Shishov, V I; Smirnova, T V; Soglasnov, V A; Zensus, J A

    2016-01-01

    We have resolved the scatter-broadened image of PSR B0329+54 and detected substructure within it. These results are not influenced by any extended structure of a source but instead are directly attributed to the interstellar medium. We obtained these results at 324 MHz with the ground-space interferometer RadioAstron which included the space radio telescope (SRT), ground-based Westerbork Synthesis Radio Telescope and 64-m Kalyazin Radio Telescope on baseline projections up to 330,000 km in 2013 November 22 and 2014 January 1 to 2. At short 15,000 to 35,000 km ground-space baseline projections the visibility amplitude decreases with baseline length providing a direct measurement of the size of the scattering disk of 4.8$\\pm$0.8 mas. At longer baselines no visibility detections from the scattering disk would be expected. However, significant detections were obtained with visibility amplitudes of 3 to 5% of the maximum scattered around a mean and approximately constant up to 330,000 km. These visibilities reflec...

  8. Qual o Papel da Escola e da Mídia na Obtenção dos Conhecimentos Astronômicos?

    Science.gov (United States)

    da Cunha, W. S.; Voelzke, M. R.; Amaral, L. H.

    2007-08-01

    É amplamente reconhecido que as pessoas em geral têm grande fascínio e interesse pela Astronomia. Por outro lado, o conteúdo dessa área incluído no ensino formal está longe de ser abrangente e suficiente para suprir a demanda. Esse interesse permite aperfeiçoar a divulgação e o ensino não formal de Astronomia através da mídia aliando a adequação do conteúdo à expectativa das pessoas. A reforma do Currículo Básico da Escola Pública da maioria dos Estados brasileiros tem introduzido Astronomia desde a pré-escola até o Ensino Médio. Num estudo realizado com 1180 alunos do Ensino Médio de seis escolas estaduais, revelou-se através da aplicação de um formulário contendo questões que abordavam conhecimentos básicos em Astronomia, como foram adquiridos tais conhecimentos e à infra-estrutura da escola. Para 66,1% dos entrevistados o professor já fez alguma apresentação a respeito de Astronomia. O presente estudo revelou também que 54,4% dos alunos entrevistados adquiriram seus conhecimentos astronômicos na escola, 18,4% através da televisão e 27,1% afirmaram que seus conhecimentos foram obtidos através de outros tipos de mídia (internet, livros didáticos, filmes e revistas). Embora o estudo revele claramente que há certo equilíbrio no meio em que os alunos obtiveram seus conhecimentos astronômicos, a mídia busca não somente sua difusão, mas a disponibilização desse conhecimento de maneira correta, que às vezes, não é atingido, apresentando conceitos sem fundamentação e incorretos. Por outro lado, no dia-a-dia escolar, é comum encontrar professores que vêm para as aulas com concepções prévias, que podem diferir substancialmente das idéias a serem ensinadas, dificultando o aprendizado de futuros conceitos científicos. Uma avaliação criteriosa, avaliando as dificuldades dos professores em determinar o sentido correto dos conceitos e observando a metodologia que utilizam no ensino, poderá proporcionar uma melhor

  9. Mediciones de irradiancia solar y capa de ozono durante el eclipse de Sol de 1994 en el Observatorio Astronómico de Rosario, Argentina

    Science.gov (United States)

    Piacentini, R. D.; Micheletti, M. I.

    We show results of measurements made during the Sun's eclipse of November 3, 1994, in Observatorio Astronómico de Rosario (32o 57' S, 60o 37' W, 25 m a.s.l.). The eclipse begin at 8:41 local hour, reached its maximum with 77% of the surface covered at 9:51 and finished at 11:04. The direct solar irradiance of 300 nm and 313 nm were able to be measured, due to the fact that during the whole period the sky remained completed uncovered (zero percent cloudiness). The measurements were made with the portable ozonometer developed by Tocho and co-workers. They show the characterictic decrease due to the occultation of the source, which is approximately proportional to the surface's diminution. When crossing the earth's atmosphere to arrive to the observation point, these irradiances are affected mainly by the ozone layer, specially the irradiance at lower wavelength, what let it to determine by comparison the thickness of this layer. The total ozone thickness distributed between the troposphere and the stratosphere shows an oscillation, whose amplitude, since the occurence of the maximum of occulation, has a mean value of 4%, and whose period is of approximately 2100 seconds, being both numbers considerably larger than the ones registred by Mims III y Mims (Geophysical Research Letters, 20, 367, 1993) during the eclipse of July 11, 1991 and by Tocho, Da Silva y Rivas (XVIII Quadriennial Ozone Symposiom, Italy, September, 1996) during the same eclipse analyzed in the present work, but observed in Salta. As complementary results, we measured the global irradiance and the ambient temperature during this astronomical event.

  10. A Reappraising of Cosmography: the Interface Between Astronomical and Geographic Studies. (Breton Title: Releitura do Conceito de Cosmografia: a Interface Entre os Estudos Astronômicos e Geográficos.) Una Relectura del Concepto de Cosmografía: la Interfase Entre los Estudios Astronómicos y Geográficos

    Science.gov (United States)

    Azevedo Sobreira, Paulo Henrique

    2012-12-01

    The concept of "Cosmography" is in disuse since the 80s of the last century, but the astronomical themes previously discussed in the school subjects of Geography and Cosmography remain in current textbooks. The use of term "Cosmography" was rescued in this research, and the study of its re-signification prompted the appearance of the term Geographic Cosmography. The Geographic Cosmography is a field of studies of the Geography, whose set of knowledge and skills is predominantly scholar. It studies the interface between terrestrial and celestial knowledge, and assigns a geographic significance to them. It examines human and natural relationships with Sidereal Space and its consequences for society and nature. O conceito de "Cosmografia" está em desuso desde os anos 80 do século XX, mas os temas astronômicos anteriormente abordados nas disciplinas escolares de Cosmografia e de Geografia permanecem nos atuais livros didáticos. O uso do termo "Cosmografia" foi resgatado nesta pesquisa e o estudo de sua ressignificação proporcionou o surgimento do termo Cosmografia Geográfica. A Cosmografia Geográfica é um campo de estudos da Geografia, cujo conjunto de conhecimentos e habilidades é predominantemente escolar. Estuda a interface entre os conhecimentos terrestres e os celestes e lhes atribui significância geográfica. Analisa as relações humanas e naturais com o Espaço Sideral e suas consequências para a sociedade e a natureza. Aunque el concepto de "Cosmografía" no se usa desde la década de los '80 del siglo pasado, los temas astronómicos que se enseñaban anteriormente en las asignaturas escolares de Cosmografía y de Geografía permanecen en los actuales libros didácticos. El uso del término "Cosmografía" fue rescatado en esta investigación y el estudio de su resignificación proporcionó el surgimiento del término Cosmografía Geográfica. La Cosmografía Geográfica es un campo de estudio de la Geografía, donde el conjunto de conocimientos y

  11. Distribution of inhomogeneities in the interstellar plasma in the directions of three distant pulsars from observations with the RadioAstron ground-space interferometer

    Science.gov (United States)

    Popov, M. V.; Andrianov, A. S.; Bartel, N.; Gwinn, C.; Joshi, B. C.; Jauncey, D.; Kardashev, N. S.; Rudnitskii, A. G.; Smirnova, T. V.; Soglasnov, V. A.; Fadeev, E. N.; Shishov, V. I.

    2016-09-01

    The RadioAstron ground-space interferometer has been used to measure the angular sizes of the scattering disks of the three distant pulsars B1641-45, B1749-28, and B1933+16. The observations were carried out with the participation of the Westerbork Synthesis Radio Telescope; two 32-m telescopes at Torun, Poland and Svetloe, Russia (the latter being one antenna of the KVAZAR network); the Saint Croix VLBA antenna; the Arecibo radio telescope; the Parkes, Narrabri (ATCA), Mopra, Hobart, and Ceduna Australian radio telescopes; and the Hartebeesthoek radio telescope in South Africa. The full widths at half maximum of the scattering disks were 27 mas at 1668 MHz for B1641-45, 0.5 mas at 1668 MHz for B1749-28, and 12.3 at 316 MHz and 0.84 mas at 1668 MHz for B1933+16. The characteristic time scales for scatter-broadening of the pulses on inhomogeneities in the interstellar plasma τsc were also measured for these pulsars using various methods. Joint knowledge of the size of the scattering disk and the scatter-broadening time scale enables estimation of the distance to the effective scattering screen d. For B1641-45, d = 3.0 kpc for a distance to the pulsar D = 4.9 kpc, and for B1749-28, d = 0.95 kpc for D = 1.3 kpc. Observations of B1933+16 were carried out simultaneously at 316 and 1668 MHz. The positions of the screen derived using the measurements at the two frequencies agree: d 1 = 2.6 and d 2 = 2.7 kpc, for a distance to the pulsar of 3.7 kpc. Two screens were detected for this pulsar from an analysis of parabolic arcs in the secondary dynamic spectrum at 1668 MHz, at 1.3 and 3.1 kpc. The scattering screens for two of the pulsars are identified with real physical objects located along the lines of sight toward the pulsars: G339.1-04 (B1641-45) and G0.55-0.85 (B1749-28).

  12. Novas tecnoloxías e ensinanza da Astronomía: explorando o Sistema Solar e simulando fenómenos astronómicos sinxelos en 1º de ESO

    OpenAIRE

    María Álvarez Lires; Irene Pérez Rodríguez; Uxío Pérez Rodríguez

    2009-01-01

    El currículo del Primer Curso de ESO incluye como contenidos obligatorios aspectos relacionados con los temas astronómicos entre los que se cuentan la identificación de los elementos del Sistema Solar, la interpretación de los fenómenos relacionados con los movimientos de la Tierra y el uso de técnicas sencillas de orientación basadas en la observación de los astros. En este artículo se propone emplear una aplicación informática gratuita, Stellarium, cuando se aborden estos temas en el aula. ...

  13. The Meanings of Astronomical Observation: An Analysis on the Basis of Relationship with Knowledge. (Spanish Title: Los Sentidos de la Observación Astronómica: un Análisis sobre la Base de la Relación con el Saber.) Os Sentidos da Observação Astronômica: Uma Análise com Base na Relação com o Saber

    Science.gov (United States)

    Klein, Alberto Eduardo; de Mello Arruda, Sergio; Meneghello Passos, Marinez; Vinicius Domenes Zapparoli, Ferdinando

    2010-12-01

    This article presents results of a research which aimed to understand the meanings that people construct for astronomical observation. The subjects, students and school teachers, initially received some instruction on how to view astronomical objects through the telescope. After the observation was realized, they were interviewed. The data analysis allowed the creation of 12 categories, later interpreted on the basis of relationship with knowledge (relation to the world, with himself and with others), as presented by Bernard Charlot. Este artículo presenta los resultados de una investigación que tuvo como objetivo comprender los sentidos que las personas construyen para la observación astronómica. Los sujetos, los estudiantes y maestros de escuela, recibieron inicialmente algunas instrucciones sobre cómo ver los objetos astronómicos a través del telescopio. Al término de la observación, fueron entrevistados. El análisis de datos permitió la creación de 12 categorías que más tarde fueron interpretadas sobre la base de la relación con el conocimiento (relación con el mundo, consigo mismo y con los demás), tal como presentado por Bernard Charlot. Este artigo apresenta resultados de uma pesquisa que objetivou entender quais os sentidos que as pessoas constroem para a observação astronômica. Os sujeitos da pesquisa, estudantes e professores do ensino médio, receberam inicialmente alguma instrução sobre como visualizar os objetos astronômicos através do telescópio. Após a realização da observação, eles foram entrevistados. A análise dos dados permitiu a elaboração de 12 categorias que foram posteriormente interpretadas com base nas relações com o saber (relação com o mundo, consigo mesmo e com o outro), conforme apresentadas por Bernard Charlot.

  14. Influencia de la marea astronómica sobre las variaciones del nivel del Río Negro en la zona de Carmen de Patagones

    Directory of Open Access Journals (Sweden)

    Enrique D'Onofrio

    2010-12-01

    Full Text Available El Río Negro, límite natural entre las provincias de Buenos Aires y Río Negro, es uno de los ríos más importantes de la Patagonia que desemboca en el Océano Atlántico. Es navegable desde su desembocadura hasta Carmen de Patagones por embarcaciones de hasta 2,04 m de calado, dificultándose por irregularidades en la profundidad aguas arriba. La onda de marea proveniente del océano Atlántico ingresa al río haciendo que este adopte un régimen semidiurno hasta Carmen de Patagones. El conocimiento de la onda de marea en este tramo del río es de fundamental importancia para la calibración de modelos numéricos, el perfeccionamiento de los sistemas de alerta de inundaciones y la toma de decisiones relacionadas con el manejo costero. En este trabajo se analizan cuatro series de mediciones de marea, dos obtenidas en el hidrómetro de Carmen de Patagones con una duración de 608 y 731 días, una de 77 días proveniente de un mareómetro instalado en el kilómetro 18 del río y una de 79 días obtenida con un sensor de presión fondeado en proximidades de Punta Redonda (desembocadura del Río Negro. Se calculan y comparan los espectros de potencia de las alturas observadas en los tres sitios para detectar los cambios energéticos producidos en la banda de frecuencias correspondientes a la marea astronómica. De su comparación surge que la energía de las componentes semidiurnas y diurnas disminuye un 22% y un 45% respectivamente desde la desembocadura del Río Negro hasta Carmen de Patagones. En contraposición se observa un ligero aumento de la energía correspondiente a las frecuencias de las componentes cuarto diurnas. Esto se debe fundamentalmente a procesos no lineales inducidos por aguas someras y a irregularidades en la morfología del fondo del río. Para obtener las amplitudes y épocas de la marea se realizan análisis armónicos por el método de cuadrados mínimos. Las amplitudes de las componentes diurnas en Carmen de Patagones

  15. Astronomical Perception of the Secondary School's Students in São Paulo's State School in Suzano City. (Spanish Title: Percepción Astronómica de Alumnos de la Enseñanza Media de la Red Estatal de San Pablo en la Ciudad de Suzano.) Percepção Astronômica de um Grupo de Alunos do Ensino Médio da Rede Estadual de São Paulo da Cidade de Suzano

    Science.gov (United States)

    França de Oliveira, Edilene; Voelzke, Marcos Rincon; Amaral, Luis Henrique

    2007-12-01

    Although Astronomy is one of the oldest Sciences in the world and many of its concepts are popular, it is possible to observe that a major part of the students do not know about them. This work aims to analyse the basic knowledge of the secondary school's students of a state school in the city of Suzano, related to the astronomical phenomena, which surround them. It was carried out a questionnaire of multiple choice to 34 students from the first grade, night classes, of the state school Batista Renzi. From the sample, 34 students, only 29.4% of them could understand the succession of the days; 20.6% could explain the seasons of the year and 20.6% had some idea about celestial objects nearer to the Earth. In turn, 67.6% correctly classified the Sun as a star; 55.9% related the Big Bang to the origin of Universe; only 20.6% identified the light-year as an unit of distance and 32.4% recognized a falling star as a meteor. The actual analysis was expanded to more 310 students of other classes, grades and periods of the same school. In this first stage, it can be noted the students' little discernment of the astronomical events and mainly the great confusion about the appropriate meaning of popular astronomical terms. Aunque la Astronomía es una de las ciencias más antiguas de la humanidad y muchos de los conceptos astronómicos son populares, se observa que una parcela significativa de los estudiantes se encuentra al margen de estas informaciones. El presente trabajo pretende analizar el nivel de conocimiento básico de los alumnos de la Enseñanza Media de la Red Estatal de la ciudad de Suzano con relación a los fenómenos astronómicos que los rodean. Con este objetivo fue elaborado un formulario constando de preguntas de selección múltipla, aplicado en el primer año nocturno de la Escuela Estatal Batista Renzi. En un universo de 34 alumnos se constató que solamente 29,4% comprendían la sucesión de los días; 20,6% explicaron correctamente las estaciones del

  16. Novas tecnoloxías e ensinanza da Astronomía: explorando o Sistema Solar e simulando fenómenos astronómicos sinxelos en 1º de ESO

    Directory of Open Access Journals (Sweden)

    María Álvarez Lires

    2009-11-01

    Full Text Available El currículo del Primer Curso de ESO incluye como contenidos obligatorios aspectos relacionados con los temas astronómicos entre los que se cuentan la identificación de los elementos del Sistema Solar, la interpretación de los fenómenos relacionados con los movimientos de la Tierra y el uso de técnicas sencillas de orientación basadas en la observación de los astros. En este artículo se propone emplear una aplicación informática gratuita, Stellarium, cuando se aborden estos temas en el aula. Se describirán algunas de las posibilidades que tiene este programa de planetario y se proporcionarán ejemplos concretos de actividades que pueden realizarse con su ayuda.

  17. Percepção astronómica de um grupo de alunos do ensino médio de uma escola da rede estadual de São Paulo

    Science.gov (United States)

    de Oliveria, E. F.; Voelzke, M. R.

    2009-03-01

    Sendo a Astronomia uma das cièncias mais antigas da humanidade, e considerando sua importáncia histórica e cultural, é de extrema releváncia que tópicos relacionados a ela sejam tratados nas escolas. Embora os Parámetros Curriculares Nacionais do Ensino Médio (PCN-EM) e as Orientaçiacute;es Complementares aos Parámetros (PCN+) apontem a importáncia de uma abordagem significativa de conceitos relacionados à Astronomia nas aulas de Física, muitos estudantes terminam o Ensino Médio (EM) sem compreender a razão de certos acontecimentos de origem celeste, ainda que estes façam parte de seu cotidiano e sejam alvos da curiosidade natural dos jovens. Da observação dessa curiosidade em alunos de uma escola pública paulista, na cidade de Suzano, surgiu o interesse em investigar os conhecimentos básicos em Astronomia dos alunos do Ensino Médio desta escola, constituindo-se este como principal objetivo desta pesquisa. Para tanto foi elaborado um questionário de múltipla escolha aplicado inicialmente a 34 alunos do primeiro ano e, posteriormente, a mais 310, distribuídos entre as très séries do Ensino Médio dos períodos matutino e noturno. Dessa forma, observou-se que 73,9% dos estudantes identificaram o Sol como sendo uma estrela, 67,1% mostraram compreender a sucessão entre dia e noite e 52,3% relacionaram o Big Bang à origem do Universo. Em contrapartida, apenas 34,5% relacionaram as estaçíes do ano à inclinação do eixo de rotação da Terra, 21,3% indicaram a influència gravitacional simultánea da Lua e do Sol como responsável pelo fenòmeno das marés, 24,5% indicaram corretamente quais são os objetos celestes mais próximos da Terra, 36,1% identificaram ano-luz como uma medida de distáncia e 34,2% reconheceram as estrelas cadentes como meteoros, evidenciando-se assim o pequeno discernimento dos estudantes quanto aos fenòmenos e termos astronòmicos do cotidiano. Além disso, foram comparadas as respostas de alun! os de diferentes s

  18. Nicolás Mascardi e a carta-relación de 1670: uma análise preliminar das observações astronômicas realizadas pelo missionário jesuíta = Nicolás Mascardi and the carta-relación de 1670: a preliminary analysis of astronomical observations carried out by the jesuit missionary

    Directory of Open Access Journals (Sweden)

    Biehl, Maico

    2014-01-01

    Full Text Available O presente artigo apresenta os resultados preliminares da pesquisa que venho desenvolvendo como bolsista PIBIC/CNPq junto ao projeto “Uma ordem de homens de religião e de ciência: difusão, produção e circulação de saberes e práticas científicas pela Companhia de Jesus (América meridional, séculos XVII e XVIII”. O subprojeto prevê o contato com as teorias astronômicas vigentes no Seiscentos e no Setecentos, com as obras de Astronomia que integravam os acervos da Ordem e com os estudos produzidos por missionários já no Novo Mundo. Assim como, a reconstituição das trajetórias de jesuítas que realizaram observações astronômicas nas reduções em que atuaram, compartilhando os seus estudos através da prática epistolar ou por meio de obras. Neste artigo, especificamente, me detenho em reconstituir brevemente a trajetória do jesuíta Nicolas Mascardi, destacando as observações astronômicas que realizou na América e as suas comunicações com demais estudiosos da astronomia.

  19. Sobre os céus e as marés do Pacífico: as observações astronômicas do jesuíta Nicolás Mascardi (Chile, século XVII

    Directory of Open Access Journals (Sweden)

    Eliane Cristina Deckmann Fleck

    2014-12-01

    Full Text Available A atuação da Companhia de Jesus na América espanhola e portuguesa constitui-se em tema de várias investigações e obras, nas quais merece destaque a dedicação de seus religiosos ao ensino e à catequese. Alguns membros da Ordem, no entanto, se dedicaram, também, a observações de fenômenos naturais, da fauna e da flora nativas e, ainda, a aspectos da geografia dos territórios em que atuaram, legando-nos uma série de estudos informados através de cartas, relatórios ou obras. Nosso propósito neste artigo é o de apresentar e analisar os registros que o padre jesuíta italiano Nicolás Mascardi fez de suas observações astronômicas e, em especial, do estudo que realizou sobre as marés do arquipélago de Chiloé durante os anos em que atuou na então Vice-Província Jesuítica do Chile, no século XVII.

  20. Evaluation of Cardiovascular Risk Scores Applied to NASA's Astronant Corps

    Science.gov (United States)

    Jain, I.; Charvat, J. M.; VanBaalen, M.; Lee, L.; Wear, M. L.

    2014-01-01

    In an effort to improve cardiovascular disease (CVD) risk prediction, this analysis evaluates and compares the applicability of multiple CVD risk scores to the NASA Astronaut Corps which is extremely healthy at selection.

  1. About the Sociedade Astronômica Brasileira and its 36th annual meeting (2011)

    Science.gov (United States)

    Janot-Pacheco, E.

    2012-12-01

    We present an overview of the Brazilian Astronomical community and of its available observational facilities. We explain how is organized the Brazilian Astronomical Society (S.A.B.) and present some information on our last annual meeting, held in 2011.

  2. Understanding the Effects of Long-duration Space Flight on Astronant Functional Task Performance

    Science.gov (United States)

    Bloomberg, Jacob J.; Batson, Crystal D.; Buxton, Roxanne E.; Feiveson, Al H.; Kofman, Igor S.; Lee, Stuart M. C.; Miller, Chris A.; Mulavara, Ajitkumar P.; Peters, Brian T.; Phillips, Tiffany; Platts, Steven H.; Ploutz-Snyder, Lori L.; Reschke, Millard F.; Ryder, Jeff W.; Stenger, Michael B.; Taylor, Laura C.

    2014-01-01

    Space flight is known to cause alterations in multiple physiological systems including changes in sensorimotor, cardiovascular, and neuromuscular systems. These physiological changes cause balance, gait and visual disturbances, cardiovascular deconditioning, and loss of muscle mass and strength. These changes may affect a crewmember's ability to perform critical mission tasks immediately after landing on a planetary surface. To understand how changes in physiological function affect functional performance, an interdisciplinary pre- and postflight testing regimen, Functional Task Test (FTT), was developed to systematically evaluate both astronaut functional performance and related physiological changes. Ultimately this information will be used to assess performance risks and inform the design of countermeasures for exploration class missions. We are currently conducting the FTT study on International Space Station (ISS) crewmembers before and after 6-month expeditions. Additionally, in a corresponding study we are using the FTT protocol on subjects before and after 70 days of 6deg head-down bed-rest as an analog for space flight. Bed-rest provides the opportunity for us to investigate the role of prolonged axial body unloading in isolation from the other physiological effects produced by exposure to the microgravity environment of space flight. Therefore, the bed rest analog allows us to investigate the impact of body unloading on both functional tasks and on the underlying physiological factors that lead to decrement in performance and then compare them with the results obtained in our space flight study. Functional tests included ladder climbing, hatch opening, jump down, manual manipulation of objects and tool use, seat egress and obstacle avoidance, recovery from a fall and object translation tasks. Physiological measures included assessments of postural and gait control, dynamic visual acuity, fine motor control, plasma volume, heart rate, blood pressure, orthostatic intolerance, upper- and lower-body muscle strength, power, endurance, control, and neuromuscular drive. ISS crewmembers were tested three times before flight, and on 1, 6, and 30 days after landing. Bed-rest subjects were tested three times before bed-rest and immediately after getting up from bed-rest as well as 1, 6, and 12 days after reambulation.

  3. Astronomía gamma con telescopios Cherenkov: hacia un observatorio astronómico abierto a la comunidad

    Science.gov (United States)

    Rovero, A. C.

    Gamma-ray astronomy is opening the way to a universe far more energetic than anyone could have imagined half a century ago. The understanding of the processes of nature which carry a large portion of the energy in the universe, has astrophysical and cosmological implications. The next gen- eration of Cherenkov telescopes, an order of magnitude more sensitive and with higher resolution than the current systems, will mean a significant step forward for ground-based gamma-ray astronomy. This paper presents the current status of this field as well as the next generation of telescopes in this energy range, which are being designed for the first international observa- tory open to the astronomical community. The Cherenkov Telescope Array project and the Argentine sites proposed for the southern observatory are described in this paper. FULL TEXT IN SPANISH

  4. Reporte de actividades de la Estación Astronómica Polar ``J.L.Sersic''

    Science.gov (United States)

    Mosconi, M.; Recabarren, P.; Ferreiro, D.; Renzi, V.; Ozu, R.

    The ``J.L.Sersic" Astronomy Polar Station, dedicated to measure environmental parameters, which describes the sky quality for astronomical purposes, operates at 78 degrees South, in Belgrano Station, since the '94/'95 Antarctic Summer Campaign. The activities are developed during the darkness period between April and August. We measure meteorological parameters, seeing, extinction coefficients and we make a monitoring of Eta Carinae. This site registers the lowest temperatures among the argentine permanent stations, and has the most stable weather conditions with continuously dark periods of several dozens of hours. The average seeing is of the order of 3.8 arc seconds, with some occasional measurements less than an arc second. The best conditions are observed at the beginning and at the end of the winter period, being the best behavior in the V and I bands. The differences on the luminosity of the stars at different HA is not too notable at high latitudes. Due to the small difference of the air mass for different HA at high latitudes, there is a very small variation in the star luminosity. So, we have not used the traditional method. We decided to apply the method of Harris et al. (1981), which is based on the treatment by mean squares of a matrix obtained from the observations of groups of objects at different heights. We obtain K coefficients, which are function of the first order coefficients (k'), of the second order (k'') and the color index (IC): K=k'+k".IC. The annual average values for '97 and '98, in the U,V,B,R,I bands, are: Year/Coeff. & K & Kv & Kb & Ku & Kr 1997 & 0.4629 & 0.3245 & 0.3668 & 0.689 & 0.5647 1998 & 0.4313 & 0.4335 & 0.4143 & 0.876 & 0.3698 The analysis of the obtained results shows that the atmosphere is unstable and too turbulent for many astronomical works. The seeing is not good enough and the extinction in the different bands is high. Belgrano Station is located inside the auroral oval and below of the ``ozone hole". Both phenomenon affect the observed parameters. The behavior of the U band and its relationship with the variations of the ozono layer and the auroral activity are very interesting subjects to be studied.

  5. Realización, análisis y aplicaciones del archivo de placas astrométricas del Observatorio Astronómico de La Plata

    OpenAIRE

    Di Sisto, Romina Paula

    1999-01-01

    La observación fotográfica de asteroides y cometas se ha llevado a cabo en el Observatorio de La Plata desde la adquisición, y puesta en funcionamiento del telescopio Astrográfico en el año 1913. Este telescopio funcionó en forma ininterrumpida hasta el año 1986, proporcionando un gran número de placas fotográficas. Durante estos años de observación el Observatorio de La Plata, ha contribuido de forma significativa en la determinación precisa de las posiciones y efemérides de asteroides y com...

  6. Addendum: 1420 and 408 MHz Continuum Observations of the IC 443/G189.6+3.3 Region[Astron. J. 127, 2277 (2004)

    Science.gov (United States)

    Leahy, D. A.

    2004-09-01

    A previous spectral index study that noted the region of flat spectral index in the southern part of IC 443 is that of Green (1986). The same region was first noted as a hard X-ray source by Keohane et al. (1997).

  7. Extracción de conocimiento en bases de datos astronómicas mediante redes de neuronas artificiales: aplicaciones en la misión Gaia

    Science.gov (United States)

    Fustes Villadóniga, Diego

    2014-02-01

    In the so-called IT era, the capabilities of data acquisition systems have increased to such an extent that it has become difficult to store all the information they produce, and analyse it. This explosion of data has recently appeared in the field of Astronomy, where an increasing number of objects are being observed on a regular basis. An example of this is the upcoming Gaia mission, which will pick up multiple properties of a billion stars, whose information will have a volume of approximately a petabyte. The analysis of a similar amount of information inevitably requires the development of new data analysis methods to extract all the knowledge it contains. This thesis is devoted to the development of data analysis methods to be integrated in the Gaia pipeline, such that knowledge can be extracted from the data collected by the mission. In order to analyze the data from the Gaia mission, the European Space Agency organized the Data Processing and Analysis Consortium (DPAC) which is composed of hundreds of scientists and engineers. DPAC is divided into eight Coordination Units (CUs). This thesis is dedicated to algorithm development in CU8, which is responsible for source classification and astrophysical parameters (AP) estimation. Methods based on Artificial Neural Networks (ANNs) are developed to perform the tasks related to two different work packages in CU8: the GSP-Spec package (GWP-823), and the OA package (GWP-836). The GSP-Spec package is responsible for estimating stellar APs by means of the Radial Velocity Spectrograph (RVS) spectrum. This work presents the development of one of the GSP-Spec modules, which is based on the application of feed-forward ANNs. A methodology is described, based on the optimization of genetic algorithms and aimed at obtaining an optimal set of configuration parameters for the ANN in each case, depending on the signal to noise ratio (SNR) in the RVS spectrum and on the type of star to parameterize. Furthermore, in order to improve the AP estimates, wavelet signal processing techniques, applied to the RVS spectrum, are studied. Despite the effectiveness shown by ANNs in estimating APs, in principle they lack the ability to provide an uncertainty value on these estimates, making it impossible to determine their reliability. Because of this, a new architecture for the ANN is presented in which the inputs and outputs are reversed, so that the ANN estimates the RVS spectrum from the APs. Such an architecture is called Generative ANN (GANN) and is applied to the AP estimation of a set of simulated RVS spectra for the Gaia mission, where it is more effective than the conventional ANN model, in the case of faint stars with low SNR. Finally, the GANN can be applied for obtaining the posterior probability of each of the APs according to the RVS spectrum, allowing for their more complete analysis. Given the nature of the Gaia mission, which is the first astronomical mission that will observe, in an unbiased way, the entire sky up to magnitude 20, a large number of outliers are expected. The OA package in CU8 handles the processing of this type of objects, which are defined as those that could not be reliably classified by the methods in the upstream classification packages. OA methods are based on the unsupervised learning of all outliers. Such learning has two parts: clustering and dimensionality reduction. The Self-Organizing Map (SOM) algorithm is selected as a basis for this learning. Its effectiveness is demonstrated when it is applied, with an optimal configuration, to the Gaia simulations. Furthermore, the algorithm is applied to real outliers from the SDSS catalog. Since a subsequent identification of the clusters obtained by the SOM is necessary, two different methods of identification are applied. The first method is based on the similarity between the SOM prototypes and the Gaia simulations, and the second method is based on the recovery of stored classifications in the SIMBAD catalog by cross-matching celestial coordinates. Thanks to the visualization of the SOM planes, and to both

  8. Extracción de conocimiento en bases de datos astronómicas mediante redes de neuronas artificiales: aplicaciones en la misión Gaia

    Science.gov (United States)

    Fustes Villadóniga, Diego

    2014-02-01

    In the so-called IT era, the capabilities of data acquisition systems have increased to such an extent that it has become difficult to store all the information they produce, and analyse it. This explosion of data has recently appeared in the field of Astronomy, where an increasing number of objects are being observed on a regular basis. An example of this is the upcoming Gaia mission, which will pick up multiple properties of a billion stars, whose information will have a volume of approximately a petabyte. The analysis of a similar amount of information inevitably requires the development of new data analysis methods to extract all the knowledge it contains. This thesis is devoted to the development of data analysis methods to be integrated in the Gaia pipeline, such that knowledge can be extracted from the data collected by the mission. In order to analyze the data from the Gaia mission, the European Space Agency organized the Data Processing and Analysis Consortium (DPAC) which is composed of hundreds of scientists and engineers. DPAC is divided into eight Coordination Units (CUs). This thesis is dedicated to algorithm development in CU8, which is responsible for source classification and astrophysical parameters (AP) estimation. Methods based on Artificial Neural Networks (ANNs) are developed to perform the tasks related to two different work packages in CU8: the GSP-Spec package (GWP-823), and the OA package (GWP-836). The GSP-Spec package is responsible for estimating stellar APs by means of the Radial Velocity Spectrograph (RVS) spectrum. This work presents the development of one of the GSP-Spec modules, which is based on the application of feed-forward ANNs. A methodology is described, based on the optimization of genetic algorithms and aimed at obtaining an optimal set of configuration parameters for the ANN in each case, depending on the signal to noise ratio (SNR) in the RVS spectrum and on the type of star to parameterize. Furthermore, in order to improve the AP estimates, wavelet signal processing techniques, applied to the RVS spectrum, are studied. Despite the effectiveness shown by ANNs in estimating APs, in principle they lack the ability to provide an uncertainty value on these estimates, making it impossible to determine their reliability. Because of this, a new architecture for the ANN is presented in which the inputs and outputs are reversed, so that the ANN estimates the RVS spectrum from the APs. Such an architecture is called Generative ANN (GANN) and is applied to the AP estimation of a set of simulated RVS spectra for the Gaia mission, where it is more effective than the conventional ANN model, in the case of faint stars with low SNR. Finally, the GANN can be applied for obtaining the posterior probability of each of the APs according to the RVS spectrum, allowing for their more complete analysis. Given the nature of the Gaia mission, which is the first astronomical mission that will observe, in an unbiased way, the entire sky up to magnitude 20, a large number of outliers are expected. The OA package in CU8 handles the processing of this type of objects, which are defined as those that could not be reliably classified by the methods in the upstream classification packages. OA methods are based on the unsupervised learning of all outliers. Such learning has two parts: clustering and dimensionality reduction. The Self-Organizing Map (SOM) algorithm is selected as a basis for this learning. Its effectiveness is demonstrated when it is applied, with an optimal configuration, to the Gaia simulations. Furthermore, the algorithm is applied to real outliers from the SDSS catalog. Since a subsequent identification of the clusters obtained by the SOM is necessary, two different methods of identification are applied. The first method is based on the similarity between the SOM prototypes and the Gaia simulations, and the second method is based on the recovery of stored classifications in the SIMBAD catalog by cross-matching celestial coordinates. Thanks to the visualization of the SOM planes, and to both methods of identification, it is possible to distinguish between valid observations and observational artifacts. Furthermore, the method allows for the selection of objects of interest for follow-up observations, in order to determine their nature.

  9. Mesa redonda: Argentina en proyectos globales de investigaciones espaciales y astronómicas. Uso científico de la Antena de Espacio Profundo DSA 3

    Science.gov (United States)

    Colazo, M.

    2016-08-01

    Argentine has 10 percent of the operative time available for the DSA 3 Antenna of the European Space Agency, installed in Malargüe, Mendoza. Here we present the history of the project and the current activities for the scientific use of the antenna.

  10. Mesa redonda: Argentina en proyectos globales de investigaciones espaciales y astronómicas. Astronomía óptica en Argentina

    Science.gov (United States)

    Folatelli, G.

    2016-08-01

    This is a brief summary of the current status of observational astronomy in the optical range in Argentina, as seen by the author. This roundtable presentation aimed at setting off the discussion within the community about the issue of observational facilities and its posible solutions.

  11. Estación Astronómica Antártica José L. Sérsic: reporte 1996

    Science.gov (United States)

    Recabarren, P.; Mosconi, M.; Lazarte, G.; Cavarra, M.; Daguerre, F.

    Se presenta el estado de avance de los programas de observación en desarrollo en la estación ``J.~L.~SERSIC'', en Base Belgrano, a los 78 grados de latitud Sur. Se comentan algunas soluciones a los problemas que impone el riguroso ambiente polar en cuanto al funcionamiento y operación de los equipos.

  12. Maximum mass ratio of am CVn-type binary systems and maximum white dwarf mass in ultra-compact x-ray binaries (addendum - Serb. Astron. J. No. 183 (2011, 63

    Directory of Open Access Journals (Sweden)

    Arbutina B.

    2012-01-01

    Full Text Available We recalculated the maximum white dwarf mass in ultra-compact X-ray binaries obtained in an earlier paper (Arbutina 2011, by taking the effects of super-Eddington accretion rate on the stability of mass transfer into account. It is found that, although the value formally remains the same (under the assumed approximations, for white dwarf masses M2 >~0.1MCh mass ratios are extremely low, implying that the result for Mmax is likely to have little if any practical relevance.

  13. Análise sobre o Conhecimento de um Grupo de Alunos do Ensino Médio da Rede Estadual de São Paulo sobre Termos e Fenômenos Astronômicos do Cotidiano

    Science.gov (United States)

    de Oliveira, E. F.; Voelzke, M. R.; Amaral, L. H.

    2007-08-01

    Embora os Parâmetros Curriculares Nacionais do Ensino Médio (PCN-EM) e as orientações complementares a esses Parâmetros (PCN+) apontem a importância de uma abordagem significativa de conceitos relacionados à astronomia nas aulas de Física, muitos estudantes terminam o Ensino Médio (EM) sem compreender a razão de certos acontecimentos de origem celeste, ainda que estes façam parte de seu cotidiano. Este trabalho tem por objetivo analisar os conhecimentos básicos em astronomia dos alunos de EM da escola estadual Batista Renzi, bem como investigar os meios através dos quais estes conhecimentos foram adquiridos. Para tanto foi elaborado um questionário de múltipla escolha aplicado a 310 alunos distribuídos entre as três séries do EM dos períodos matutino e noturno. Dessa forma, observou-se que apenas 34,5% relacionaram as estações do ano à inclinação do eixo de rotação da Terra, 21,3% indicaram a influência gravitacional da Lua e do Sol como responsáveis pelo fenômeno das marés, 24,5% indicaram corretamente quais são os objetos celestes mais próximos da Terra, 36,1% identificaram ano-luz como uma medida de distância e 34,2% reconheceram uma estrela cadente como meteoro. Em contrapartida, 67,1% compreendiam a sucessão entre dia e noite, 73,9% identificaram o Sol como estrela e 52,3% relacionaram o Big Bang à origem do Universo. Além disso, foram comparadas as respostas de alunos de diferentes séries e períodos, observando-se, dentre outras coisas, que os estudantes do terceiro ano apresentam um percentual de acertos semelhante ao dos alunos do primeiro, caracterizando que a abordagem de tópicos relacionados à astronomia no EM não tem contribuído para uma maior compreensão dos fenômenos e conceitos.

  14. Desarrollo de una Interfaz de Control para un Observatorio Astronómico Robotizado con fines educativos en la Facultad de Ciencias Exactas; Físicas y Naturales de la UNSJ

    Science.gov (United States)

    Pogrebinsky, L.; Francile, C.

    We report the development and the construction of an Interface to Control a robotized Astronomical Observatory (ICOA), which allows to control the operation of an observatory based on a Meade LX200 telescope. The interface operates together with a computer to control and supervise all the local variables of the observatory, and can take the control of it in risky situations. It serves as a link among the control computer and all the necessary devices for the astronomical observation such as the telescope, the dome, the weather station, the CCD camera, the calibration devices and the security devices. The computer receives orders from an operator who can be or not at the site of observation. The goal of this robotized observatory is the operation in a secure, autonomous and unattended way, with the purpose of to be used remotely by the students of the "Facultad de Ciencias Exactas, Físicas y Naturales" of the UNSJ. FULL TEXT IN SPANISH

  15. Conocimientos astronómicos del profesorado de educación secundaria obligatoria y preferencias metodológicas para la enseñanza de astronomía

    Directory of Open Access Journals (Sweden)

    José Luis GARCÍA HERRERO

    2014-11-01

    Full Text Available La astronomía forma parte del currículo de las materias científicas en la educación obligatoria, incluyendo básicamente unos pocos conceptos tradicionales como las estaciones del año, las fases lunares, los movimientos de la Tierra, los eclipses…, y dejando de lado otros más actuales como los exoplanetas y la cosmología. Este artículo pretende estudiar en primer lugar el nivel de conocimientos básicos sobre astronomía del profesorado de Educación Secundaria Obligatoria (ESO, con el fin de detectar posibles carencias formativas y concepciones alternativas. En el estudio participaron profesores de especialidades científicas y no científicas de dicha etapa. Posteriormente se realizó un análisis de correlación de resultados en función de diversas variables, y además se comparó con los resultados obtenidos por un extenso grupo de alumnos de ESO. En segundo lugar, el artículo se centra en estudiar las preferencias metodológicas para la enseñanza-aprendizaje de astronomía, contando con los mismos participantes que en el caso anterior, y con el objetivo de conocer sus valoraciones sobre diferentes propuestas, en algunos casos bastante innovadoras. Los resultados obtenidos pueden ser orientativos para estudios posteriores de mayor envergadura, de cara a la determinación de necesidades de formación específicas en astronomía en el caso de docentes de materias científicas. Además, serán de utilidad como orientaciones metodológicas a la hora de abordar la enseñanza de la astronomía.

  16. Conocimientos astronómicos del profesorado de educación secundaria obligatoria y preferencias metodológicas para la enseñanza de astronomía

    OpenAIRE

    José Luis GARCÍA HERRERO

    2014-01-01

    La astronomía forma parte del currículo de las materias científicas en la educación obligatoria, incluyendo básicamente unos pocos conceptos tradicionales como las estaciones del año, las fases lunares, los movimientos de la Tierra, los eclipses…, y dejando de lado otros más actuales como los exoplanetas y la cosmología. Este artículo pretende estudiar en primer lugar el nivel de conocimientos básicos sobre astronomía del profesorado de Educación Secundaria Obligatoria (ESO), con el fin de de...

  17. Fluctuaciones interanuales a multidecádicas de la temperatura de verano en el centro-oeste de Argentina y procesos atmosféricos/oceánicos/astronómicos globales

    Directory of Open Access Journals (Sweden)

    Eduardo Andres Agosta

    2008-12-01

    Full Text Available La temperatura estival (octubre-marzo en la región Centro-Oeste de Argentina (COA, 28°-36°S y 65°-70°O tiene un comportamiento espacial coherente y temporal en fase, en escalas interanuales a interdecádicas (Agosta y otros 2004. Se encuentra que la temperatura del aire presenta cuasi-oscilaciones significativas en las bandas de 11 años y 18 años aproximadamente. La primera se vincula al forzante solar, la segunda, a los efectos de la transición climática de 1976/77 (IPCC, 2001. Esta transición afectó transitoriamente la variabilidad de baja frecuencia de la temperatura como fenómeno de interferencia sobre el cuasi-ciclo solar de 11 años dominante.The summer (Oct-Mar temperature in Central-West Argentina (CWA, 28°-36°S y 65°-70°W shows a behaviour spatially coherent and temporally in phase at interannual to interdecadal scales. (Agosta et al. 2004. It is found the air temperature shows significant cuasi-oscillations in the spectral bands of roughly 11-yr. and 18- yr. The former is linked to the solar forcing, the latter to the effects of the climate transition of the summer 1976/77 (IPCC 2001. This transition transitorily affected the low-frequency variability of the temperature as an interference phenomenon upon the cuasi-11-yr.-solar cycle domain.

  18. Inclusion of Astronomy Themes in an Inovative Approach of Informal Physics Teaching for High School Students. (Spanish Title: Inclusión de Temas Astronómicos en Uma Abordaje Innovadora de la Enseñanza Informal de Física Para Estudiantes de Secumdaria.) Inclusão de Temas Astronômicos Numa Abordagem Inovadora do Ensino Informal de Física Para Estudantes do Ensino Médio

    Science.gov (United States)

    Tiara Mota, Aline; de Morais Bonomini, Iracema Ariel; Meloni Martins Rosado, Ricardo

    2009-12-01

    The current work reports on an experience on Astronomy education at the Federal University of Itajubá through an extra-curricular course offered for High School students. This initiative was motivated by the low attention paid to the Astronomy subjects at this stage of the Brazilian Formal Education, in spite that the National Curricular Parameters (PCN and PCN+, in Brazil) point out the importance of their inclusion Este artículo relata una experiencia en la enseñanza de la astronomía efectuada en la Universidad Federal de Itajubá en la forma de un curso de extensión orientado para los estudiantes del colegio secundario. Esta iniciativa surgió de constatar la poca atención dada a la Astronomía en esta etapa de la Educación formal brasileña, a pesar que los Parámetros Curriculares Nacionales (PCN y PCN+, en Brasil) destacan la importancia de su inclusión. Este artigo relata uma experiência em ensino de Astronomia realizada na Universidade Federal de Itajubá na forma de um curso de extensão voltado para alunos do Ensino Médio. Esta iniciativa surgiu da pouca atenção que se dá à Astronomia nesta etapa da Educação embora os Parâmetros Curriculares Nacionais (PCN e PCN+) apontem a importância de sua inclusão.

  19. La teoría de la armonía de las esferas en el libro quinto de Harmonices Mundi de Johannes Kepler

    OpenAIRE

    García Martín, Rubén

    2009-01-01

    [EN]El presente trabajo es presidido por tres objetivos: 1-Estudiar y comprobar de manera detallada la teoría astronómico-musical expuesta en el libro quinto de Harmonices Mundi de Johannes Kepler. 2- Averiguar si hay relaciones entre el planteamiento astronómico kepleriano y la práctica y teoría musicales que este autor conocía. 3- Averiguar si las teorías astronómicas tienen en Kepler una influencia sobre las teorías musicales, en el caso particular de la teoría de la consonancia....

  20. Optimization for high fidelity imaging with aperture array telescopes

    NARCIS (Netherlands)

    Noorishad, Parisa

    2013-01-01

    ASTRON, het Nederlandse instituut voor radiosterrenkunde, heeft LOFAR ontwikkeld en gerealiseerd; een instrument met een onconventioneel ontwerp: fasegestuurde antennes. Dit ontwerp maakt het een stuk goedkoper en sneller om een grote telescoop op te bouwen. Ook zijn de wetenschappelijke toepassinge

  1. First test of the dragon equipment

    Directory of Open Access Journals (Sweden)

    V. V. Voitsekhovich

    2005-01-01

    Full Text Available El equipo DRAGON constituye un nuevo instrumento astronómico diseñado para llevar a cabo diversas investigaciones relacionadas con óptica adaptativa, óptica activa, astronomía observacional e instrumentación astronómica. En este artículo presentamos los resultados de las primeras pruebas de este instrumento llevadas a cabo en el OAN-Tonantzintla (México.

  2. Spectral behavior of AM Her and QQ Vul in high and intermediate states in the UV

    Science.gov (United States)

    Sanad, M. R.

    2010-12-01

    We present low resolution UV spectra of two polar systems, AM Her and QQ Vul from the observations taken by the IUE (International Ultraviolet Explorer) of the period between 1978-1996 and 1983-1996 for both systems respectively, to accomplish a large scale study of what happens to the ultraviolet flux of C IV 1550 Å spectral line during different orbital phases. Two spectra for both systems showing the variations in line fluxes and line widths at different orbital phases in high and intermediate states are presented. We concentrated on calculating the line fluxes and line widths of C IV 1550 Å emission line originating in the accretion stream. Our results show that there is spectral variability for the aformentioned physical parameters at different times, similar to that known for the light curve (Heise and Verbunt, Astron. Astrophys. 189:112, 1988; Gansicke et al., Astron. Astrophys. 303:127, 1995; Kafka and Honeycutt, Astron. J. 125:2188K, 2003). We attribute it to the variations of both density and temperature as a result of changing the mass transfer rate (Hutchings et al., Astron. J. 123:2841H, 2002; King and Lasota, Astron. Astrophys. 140L:16K, 1984) which is responsible for this spectral variability. Also we found that the line fluxes of AM Her are greater than the line fluxes of QQ Vul, while the line widths of both systems are approximately the same.

  3. Building the cosmic distance scale: from Hipparcos to Gaia

    CERN Document Server

    Turon, Catherine; Masana, Eduard

    2012-01-01

    Hipparcos, the first ever experiment of global astrometry, was launched by ESA in 1989 and its results published in 1997 (Perryman et al., Astron. Astrophys. 323, L49, 1997; Perryman & ESA (eds), The Hipparcos and Tycho catalogues, ESA SP-1200, 1997). A new reduction was later performed using an improved satellite attitude reconstruction leading to an improved accuracy for stars brighter than 9th magnitude (van Leeuwen & Fantino, Astron. Astrophys. 439, 791, 2005; van Leeuwen, Astron. Astrophys. 474, 653, 2007). The Hipparcos Catalogue provided an extended dataset of very accurate astrometric data (positions, trigonometric parallaxes and proper motions), enlarging by two orders of magnitude the quantity and quality of distance determinations and luminosity calibrations. The availability of more than 20000 stars with a trigonometric parallax known to better than 10% opened the way to a drastic revision of our 3-D knowledge of the solar neighbourhood and to a renewal of the calibration of many distance ...

  4. San Pedro Mártir: Characteristics of the site for optical and infrared Observations

    Directory of Open Access Journals (Sweden)

    Mauricio Tapia

    2007-01-01

    Full Text Available El Observatorio Astron mico Nacional est localizado en la Sierra San Pedro M rtir, en la pen nsula de Baja California, M xico, a una elevaci n de 2800 m. sobre el nivel del mar. Sus coordenadas son 31◦02 40 N y 115◦28 00 W. Aqu se presentan los resultados resumidos de casi tres d cadas de recabar informaci n sobre la caracterizaci n astron mica del sitio. Se cubren los siguientes aspectos: tiempo, nubosidad, meteorolg a local, opacidad atmosf rica en el optico y milim etrico, calidad de imagen, perfiles de turbulencia y de viento, y simulaciones 3D de turbulencia atmosf rica. Se concluye que San Pedro M rtir es uno de los sitios accesibles del planeta con mejores condiciones para las observaciones astron micas y en particular para instalar grandes telescopios. La UNAM y otras instituciones internacionales est n llevando a cabo estudios de muy largo plazo para establecer mejor estos resultados

  5. Modeling and optimization of the antenna system with focal plane array for the new generation radio telescopes with wide field of view

    CERN Document Server

    Iupikov, O

    2016-01-01

    The model of the reflector antenna system with focal plane array, low-noise amplifier and beamformer is developed in the work. The beamformer strategy is suggested to reduce the receiving sensitivity ripple inside field of view of the telescope, while the sensitivity itself drops slightly (less than 10%). The system APERTIF (which is currently under development in Netherlands Institute For Radioastronomy, ASTRON) has been analyzed using developed model, and numerical results are presented. The obtained numerical results have been verified experimentally in anechoic chamber as well as on one of the dishes of the Westerbork Synthesis Radio Telescope (all measurements have been done in ASTRON).

  6. Resguardando el legado de Newton : Vitrina para el libro Philosophiae naturalis principia mathematica de Isaac Newton

    OpenAIRE

    Peralta, Romina Alejandra; Canaparo, Juan Francisco

    2013-01-01

    Diseño y construcción de una vitrina para albergar un antiguo libro de Isaac Newton perteneciente a la Facultad de Ciencias Astronómicas y Geofísicas de la UNLP paa su preservación. (Párrafo extraído del texto a modo de resumen)

  7. YSO Clusters on Galactic Infrared Loops

    Science.gov (United States)

    Marton, Gábor; Kiss, Zoltán Tamás; Tóth, L. Viktor; Zahorecz, Sarolta; Pásztor, László; Ueno, Munateka; Kitamura, Yoshimi; Tamura, Motohide; Kawamura, Akiko; Onishi, Toshikazu

    The AKARI all sky survey (Murakami et al. Publ. Astron. Soc. Jpn. 59:369, 2007) was investigated for YSO candidates. Distribution of candidate sources have been analysed and compared to that of galactic CO and medium scale structures. Clustering and other inhomogenities have been found.

  8. Nancay blind 21cm line survey of the Canes Venatici group region

    NARCIS (Netherlands)

    Kraan-Korteweg, R. C.; Driel, W. van; Briggs, F.; Binggeli, B.; Mostefaoui, T. I.

    1998-01-01

    Submitted to: Astron. Astrophys. Abstract: A radio spectroscopic driftscan survey in the 21cm line with the Nancay Radio Telescope of 0.08 steradians of sky in the direction of the constellation Canes Venatici covering a heliocentric velocity range of -350 < V_hel < 2350 km/s produced 53 spectral fe

  9. The fundamental plane of elliptical galaxies with modified Newtonian dynamics

    NARCIS (Netherlands)

    Sanders, R. H.

    1999-01-01

    Submitted to: Mon. Not. R. Astron. Soc. Abstract: The modified Newtonian dynamics (MOND), suggested by Milgrom as an alternative to dark matter, implies that isothermal spheres with a fixed anisotropy parameter should exhibit a near perfect relation between the mass and the fourth power of the veloc

  10. The LOFAR Pulsar Data Pipeline

    NARCIS (Netherlands)

    A. Alexov; J. Hessels; J.D. Mol; B. Stappers; J. van Leeuwen

    2009-01-01

    The LOw Frequency ARray (LOFAR) for radio astronomy is being built in the Netherlands by ASTRON, with extensions throughout Europe. LOFAR operates at radio frequencies below 250 MHz. The project is an interferometric array of radio antennas grouped into stations that are distributed over an area of

  11. LOFAR and HDF5: toward a new radio data standard

    NARCIS (Netherlands)

    K. Anderson; A. Alexov; L. Baehren; J.M. Griessmeier; M.W. Wise; G.A. Renting; I.N. Evans; A. Accomazzi; D.J. Mink; A.H. Rots

    2011-01-01

    For decades now, scientific data volumes have experienced relentless, exponential growth. As a result, legacy astronomical data formats are straining under a burden not conceived of when these formats were first introduced. With future astronomical projects ensuring this trend, ASTRON and the LOFAR

  12. LOFAR and HDF5: Toward a new radio data standard

    NARCIS (Netherlands)

    K.R. Anderson; A. Alexov; L. Båhren; J.M. Grießmeier; M. Wise; G.A. Renting

    2010-01-01

    For decades now, scientific data volumes have experienced relentless, exponential growth. As a result, legacy astronomical data formats are straining under a burden not conceived when these formats were first introduced. With future astronomical projects ensuring this trend, ASTRON and the LOFAR pro

  13. The Cusp/Core problem: supernovae feedback versus the baryonic clumps and dynamical friction model

    Science.gov (United States)

    Del Popolo, A.; Pace, F.

    2016-05-01

    In the present paper, we compare the predictions of two well known mechanisms considered able to solve the cusp/core problem (a. supernova feedback; b. baryonic clumps-DM interaction) by comparing their theoretical predictions to recent observations of the inner slopes of galaxies with masses ranging from dSphs to normal spirals. We compare the α-V_{rot} and the α-M_{ast} relationships, predicted by the two models with high resolution data coming from Adams et al. (Astrophys. J. 789, 63, 2014), Simon et al. (Astrophys. J. 621, 757, 2005), LITTLE THINGS (Oh et al. in Astron. J. 149, 180, 2015), THINGS dwarves (Oh et al. in Astron. J. 141, 193, 2011a; Oh et al. in Astron. J. 142, 224, 2011b), THINGS spirals (Oh et al. in Astron. J. 149, 180, 2015), Sculptor, Fornax and the Milky Way. The comparison of the theoretical predictions with the complete set of data shows that the two models perform similarly, while when we restrict the analysis to a smaller subsample of higher quality, we show that the method presented in this paper (baryonic clumps-DM interaction) performs better than the one based on supernova feedback. We also show that, contrarily to the first model prediction, dSphs of small mass could have cored profiles. This means that observations of cored inner profiles in dSphs having a stellar mass <106 M_{⊙} not necessarily imply problems for the ΛCDM model.

  14. 76 FR 38018 - Safety Zone, Newport River; Morehead City, NC

    Science.gov (United States)

    2011-06-29

    ... standards are technical standards (e.g., specifications of materials, performance, design, or operation... in the Federal Register (33 FR 165). We received no comments on the proposed rule. No public meeting... Transportation awarded a contract to Astron General Contracting Company of Jacksonville, NC to perform...

  15. El Observatorio de San Pedro Mártir: A World-Class Site for Large Telescopes

    Directory of Open Access Journals (Sweden)

    Peter A. Wehinger

    2007-01-01

    Full Text Available Se describen las características de San Pedro Mártir como un sitio superior para telescopios astronómicos de gran tamaño. El cielo extremadamente oscuro, el alto porcentaje de noches despejadas durante todo el a˜no, el seeing excelente, el bajo contenido de vapor de agua y los aspectos logísticos relacionados hacen a SPM el sitio número uno para nuevos proyectos de grandes telescopios. Ciertamente, SPM es un sitio muy atractivo, al cual se puede llegar fácilmente por tierra, mar y aire con rutas de abastecimiento significativamente cortas y que permite acceder en un solo d´ıa desde Santa Cruz, Pasadena, Tucson, San Diego, la Cd. de México y otros centros astronómicos

  16. Site testing at san Pedro Mártir

    Directory of Open Access Journals (Sweden)

    Mauricio Tapia

    2007-01-01

    Full Text Available El Observatorio Astronómico Nacional esta localizado en la Sierra San Pedro Mártir, en la península de Baja California, México, a una elevación de 2800 m sobre el nivel del mar. Sus coordenadas son 31_0204000 N y 115_2800000 W. Aquí se presentan los resultados resumidos de mas de tres décadas de recabar información sobre la caracterización astronómica del sitio. Se cubren los siguientes aspectos: estabilidad atmosférica, calidad de imagen, opacidad atmosférica en el visible, infrarrojo y milimétrico, brillo del cielo nocturno y nubosidad. La Universidad Nacional Autónoma de México y otras instituciones internacionales están llevando a cabo estudios de muy largo plazo para establecer mejor los resultados

  17. E1 transitions among the levels of the 3d5, 3d44s and 3d44p configurations in Fe IV

    International Nuclear Information System (INIS)

    Two recently published sets of data for oscillator strengths of transitions between fine-structure levels belonging to the 3d5, 3d44s and 3d44p configurations in Fe IV (Nahar and Pradhan 2005 Astron. Astrophys. 437 345; Nahar 2006 Astron. Astrophys. 448 779) show some considerable disagreements for a number of transitions. The former calculation was undertaken using the R-matrix code, in LS coupling followed by a frame transformation to obtain data for individual lines; the latter calculation used the SUPERSTRUCTURE code which provides data for individual lines directly. We discuss these differences in the light of extensive calculations of our own, using the CIV3 code. It becomes apparent that the problem lies in the 2006 calculation, and we offer some quantitative explanation of how this discrepancy has occurred. In some cases at least, it can be attributed to mis-identification of energy level labels. (fast track communication)

  18. MEASUREMENT OF CFHT IMAGES I. IDENTIFICATION, PHOTOMETRY AND CLASSIFICATION

    Directory of Open Access Journals (Sweden)

    J. H. Calderón

    2014-01-01

    Full Text Available En este trabajo presentamos resultados preliminares de la medici ́n y an ́lisis de im ́genes de la zona ecliptical o a a obtenidas con la C ́mara MegaCam instalada en el Canada-France-Hawaii Telescope (CFHT ubicado en Mauna a Kea (Hawaii. Se est ́ evaluando la posibilidad de construir un cat ́logo astrom ́trico y fotom ́trico de las a a e e fuentes astron ́micas identificadas en las mencionadas im ́genes. En esta presentaci ́n se comentan y discuten o a o los criterios empleados y procedimientos aplicados para la identificaci ́n, reducci ́n fotom ́trica y clasificaci ́n o o e o de las fuentes astron ́micas como estelares o extendidas.

  19. LETTERS FROM THE PUBLIC: A PORTRAIT OF POPULAR ASTRONOMY IN MEXICO (1918-1947

    Directory of Open Access Journals (Sweden)

    S. Biro

    2011-01-01

    Full Text Available Las cartas que recibió Joaquín Gallo en el periodo en que fue director del Observatorio Astronómico Nacional (OAN nos muestran atisbos de la astronomía presente en la cultura mexicana en la primera mitad del siglo XX. Una revisión de los intereses y motivaciones de los autores de estas cartas produce un retrato de los mexicanos interesados en la astronomía.

  20. Different approaches to the thermonuclear fusion problem

    International Nuclear Information System (INIS)

    Some alternative approaches to the problem of a controlled fusion are given in brief. Advantages, shortcomings and problems are considered while developing the following approaches: a corrugated torus, an astron, toroidal Z-pinch, a stellarator, a torsatron, a tormak, a topolotron, a surmak, fusion in a target, irradiated by an electron beam, a dense plasma focus, a compressed linear and fusion in a laser heating solenoid

  1. Effects of the Number of Active Receiver Channels on the Sensitivity of a Reflector Antenna System with a Multi-Beam Wideband Phased Array Feed

    CERN Document Server

    Iupikov, O

    2016-01-01

    A method for accurate modeling of a reflector antenna system with a wideband phased array feed is presented and used to study the effects of the number of active antenna elements and associated receiving channels on the receiving sensitivity of the antenna system. Numerical results are shown for a practical design named APERTIF that is currently under developed at The Netherlands Institute for Radio Astronomy (ASTRON).

  2. Hydrodynamic simulations of moonlet induced propellers and the size of Blériot

    Science.gov (United States)

    Seiss, Martin; Albers, Nicole; Sremcevic, Miodrag; Schmidt, Jürgen; Salo, Heikki; Hoffmann, Holger; Spahn, Frank

    2016-10-01

    Small moons embedded in Saturn's rings can cause S-shaped density structures in their close vicinity called propellers. These structures have been predicted on base of a combined model involving gravitational scattering of test particles (creating the structure) and diffusion (smearing out the structure, see Spahn and Sremčević (2000, Astron. Astrophys.) and Sremčević et al. (2002,MNRAS)). The propeller model was confirmed later by N-body simulations, which additionally show the appearance of moonlet wakes adjacent to the S-shaped gaps (Seiß et al., 2005, GRL; Lewis and Stewart, 2009, Astron. J.). It was a great success of the Cassini mission when propellers were detected in the data of the ISS (Tiscareno et al., 2006, Nature; Sremčević et al., 2007, Nature; Tiscareno et al., 2008, Astron. J. and 2010, ApJL) and UVIS (Baillié et al., 2013) instruments.Here we present isothermal hydrodynamic simulations of propellers as a further development of the original model (Spahn and Sremčević, 2000, Astron. Astrophys.) where gravitational scattering and diffusion had to be treated separately. We confirm the correctness of the predicted scaling laws for the radial and azimuthal extent of propellers and show that the analytical solution by Sremčević et al. (2002, MNRAS) can be fitted to the azimuthal profile. Furthermore, we show that this new approach is in a good agreement with N-body simulations performed with parameters suitable for the A-ring. Finally, we present simulation results of the giant propeller Blériot and fit them to optical depth profiles gathered by the UVIS experiment aboard of the spacecraft Cassini. The fits are consistent using 600 m for the Hill radius of the moonlet and 350 cm2/s for the kinematic shear viscosity.

  3. Astronomía y Física: un matrimonio Sartriano

    Science.gov (United States)

    Vucetich, H.

    Desde el siglo XVII, Física y Astronomía han formado un matrimonio similar al de Sartre y Beauvoir: lleno de amores contingentes, pero firme y duradero. En la charla examino tres de los frutos más recientes de este matrimonio: - La confirmación de la Relatividad General con datos astronómicos. - Astrofísica y Física de neutrinos. - Teorías de supercuerdas y astronomía.

  4. LOFAR and HDF5: Toward a new radio data standard

    OpenAIRE

    Anderson, K R; Alexov, A.; Båhren, L.; Grießmeier, J.M.; Wise, M.; Renting, G.A.

    2010-01-01

    For decades now, scientific data volumes have experienced relentless, exponential growth. As a result, legacy astronomical data formats are straining under a burden not conceived when these formats were first introduced. With future astronomical projects ensuring this trend, ASTRON and the LOFAR project are exploring the use of the Hierarchical Data Format, version 5 (HDF5), for LOFAR radio data encapsulation. Most of LOFAR's standard data products will be stored using the HDF5 format. In add...

  5. Estudio del horizonte local

    OpenAIRE

    Ros Ferré, Rosa Maria

    2009-01-01

    El estudio del horizonte es fundamental para poder facilitar las primeras observaciones de los alumnos en un centro educativo. Un simple modelo, que debe realizarse para cada centro, nos permite facilitar el estudio y la comprensión de los primeros rudimentos astronómicos. El modelo construido se presenta a su vez como un sencillo modelo de reloj ecuatorial y a partir de él se pueden construir otros modelos (horizontal y vertical).

  6. Microsat I: videocámaras

    Science.gov (United States)

    Recabarren, P.; Sanchez, J.

    El 28 de agosto de 1996 se lanzó desde el Cosmódromo ruso de Pletzek el primer satélite enteramente construído en el país. El Observatorio Astronómico de Córdoba estuvo a cargo del espacializado de las cámaras de video. Se presentan aspectos técnicos del trabajo.

  7. Molecular Beam Optical Zeeman Spectroscopy of Vanadium Monoxide, VO

    Science.gov (United States)

    Nguyen, Trung; Zhang, Ruohan; Steimle, Timothy

    2016-06-01

    Like almost all astronomical studies, exoplanet investigations are observational endeavors that rely primarily on remote spectroscopic sensing to infer the physical properties of planets. Most exoplanet related information is inferred from to temporal variation of luminosity of the parent star. An effective method of monitoring this variation is via Magnetic Doppler Imaging (MDI), which uses optical polarimetry of paramagnetic molecules or atoms. One promising paramagnetic stellar absorption is the near infrared spectrum of VO. With this in mind, we have begun a project to record and analyze the field-free and Zeeman spectrum of the band. A cold (approx. 20 K) beam of VO was probed with a single frequency laser and detected using laser induced fluorescence. The determined spectral parameters will be discussed and compared to those extracted from the analysis of a hot spectrum. Supported by the National Science Foundation under the Grant No. CHE-1265885. O. Kochukhov, N. Rusomarov, J. A. Valenti, H. C. Stempels, F. Snik, M. Rodenhuis, N. Piskunov, V. Makaganiuk, C. U. Keller and C. M. Johns-Krull, Astron. Astrophys. 574 (Pt. 2), A79/71-A79/12 (2015). S. V. Berdyugina, Astron. Soc. Pac. Conf. Ser. 437 (Solar Polarization 6), 219-235 (2011). S. V. Berdyugina, P. A. Braun, D. M. Fluri and S. K. Solanki, Astron. Astrophys. 444 (3), 947-960 (2005). A. S. C. Cheung, P. G. Hajigeorgiou, G. Huang, S. Z. Huang and A. J. Merer, J. Mol. Spectrosc. 163 (2), 443-458 (1994)

  8. Astronomía en la cultura

    Science.gov (United States)

    López, A.; Giménez Benitez, S.; Fernández, L.

    La Astronomía en la Cultura es el estudio interdisciplinario a nivel global de la astronomía prehistórica, antigua y tradicional, en el marco de su contexto cultural. Esta disciplina abarca cualquier tipo de estudios o líneas de investigación en que se relacione a la astronomía con las ciencias humanas o sociales. En ella se incluyen tanto fuentes escritas, relatos orales como fuentes arqueológicas, abarcando entre otros, los siguientes temas: calendarios, observación práctica, cultos y mitos, representación simbólica de eventos, conceptos y objetos astronómicos, orientación astronómica de tumbas, templos, santuarios y centros urbanos, cosmología tradicional y la aplicación ceremonial de tradiciones astronómicas, la propia historia de la astronomía y la etnoastronomía (Krupp, 1989) (Iwaniszewski, 1994). En nuestro trabajo abordamos la historia y situación actual de esta disciplina, sus métodos y sus relaciones con otras áreas de investigación.

  9. The la Plata Astronomical Data Center

    Science.gov (United States)

    Marraco, H. G.

    1990-11-01

    RESUMEN. El Centro de Datos Astron6micos tiene su sede en la Facuitad de Ciencias Astron6micas y Geofisicas d la Universidad Nacional de La Plata y funciona por convenio entre esta facultad y el Centre des Stellaires de la Universite' Louis Pasteur en Estrasburgo (CDS), Francia. La finalidad de este centro es la de proveer a los astr6nomos del area con copias de los alrededor de 500 acumulados y/o preparados por el CDS a la vez que promover la producci6n y/o acumulaci6n de en el rea. Para la realizaci6n de esta tarea se cuenta con el apoyo del Centro Superior para el Procesamiento de la Informaci6n (CESPI) de la UNLP cuyos equipos se describen. Las tareas que se estan realizando incluyen la distribuci6n de SIMBAD a los astr6nomos argentinos y se efectuan ensayos de distribuci6n en linea de CD-ROM TEST DISK del Astronomical Data Center (ADC) de la NASA que contiene los 31 mas solicitados por los astr6nomos de todo el mundo. ABSTRACl The La Plata Astronomical Data Center operates by an agreement between the Facultad de Ciencias Astron6micas y Geofisicas at La Plata University and the Centre des Donnees Stellaires of Louis Pasteur University at Strasbourg (CDS), France. The purpose of the Center is to provide to the area astronomers with copies of the catalogs they need amongst those stored and/or prepared at CDS. At the same time the center will act of the astronomical data produced within its area. K words: DATA ANALYSIS

  10. Relativistic HD and MHD modelling for AGN jets

    Science.gov (United States)

    Keppens, R.; Porth, O.; Monceau-Baroux, R.; Walg, S.

    2013-12-01

    Relativistic hydro and magnetohydrodynamics (MHD) provide a continuum fluid description for plasma dynamics characterized by shock-dominated flows approaching the speed of light. Significant progress in its numerical modelling emerged in the last two decades; we highlight selected examples of modern grid-adaptive, massively parallel simulations realized by our open-source software MPI-AMRVAC (Keppens et al 2012 J. Comput. Phys. 231 718). Hydrodynamical models quantify how energy transfer from active galactic nuclei (AGN) jets to their surrounding interstellar/intergalactic medium (ISM/IGM) gets mediated through shocks and various fluid instability mechanisms (Monceau-Baroux et al 2012 Astron. Astrophys. 545 A62). With jet parameters representative for Fanaroff-Riley type-II jets with finite opening angles, we can quantify the ISM volumes affected by jet injection and distinguish the roles of mixing versus shock-heating in cocoon regions. This provides insight in energy feedback by AGN jets, usually incorporated parametrically in cosmological evolution scenarios. We discuss recent axisymmetric studies up to full 3D simulations for precessing relativistic jets, where synthetic radio maps can confront observations. While relativistic hydrodynamic models allow one to better constrain dynamical parameters like the Lorentz factor and density contrast between jets and their surroundings, the role of magnetic fields in AGN jet dynamics and propagation characteristics needs full relativistic MHD treatments. Then, we can demonstrate the collimating properties of an overal helical magnetic field backbone and study differences between poloidal versus toroidal field dominated scenarios (Keppens et al 2008 Astron. Astrophys. 486 663). Full 3D simulations allow one to consider the fate of non-axisymmetric perturbations on relativistic jet propagation from rotating magnetospheres (Porth 2013 Mon. Not. R. Astron. Soc. 429 2482). Self-stabilization mechanisms related to the detailed

  11. La arquitectura y el diseño de exhibiciones en el Museo de La Plata

    OpenAIRE

    Inacio, María Alejandra

    2010-01-01

    El Museo se constituye en una pieza esencial, hito cultural y urbano, diseñado y construido ex profeso para serlo, cuyo emplazamiento también era una alegoría ya que se ubica en el Parque de la Ciudad integrándose con el Jardín Zoológico, el Observatorio Astronómico y la Escuela de Bellas Artes y Oficios. Entre 1884-1887 el Museo fue construido con una arquitectura monumental y clásica que imitaba el ideal del Museo Británico. Tímpano, frontis y amplias columnas fueron los elementos simból...

  12. Gravitational Rutherford scattering and Keplerian orbits for electrically charged bodies in heterotic string theory

    Energy Technology Data Exchange (ETDEWEB)

    Villanueva, J. R., E-mail: jose.villanuevalob@uv.cl [Instituto de Física y Astronomía, Universidad de Valparaíso, Gran Bretaña 1111, Valparaíso (Chile); Centro de Astrofísica de Valparaíso, Gran Bretaña 1111, Playa Ancha, Valparaíso (Chile); Olivares, Marco, E-mail: marco.olivaresr@mail.udp.cl [Facultad de Ingeniería, Universidad Diego Portales, Avenida Ejército Libertador 441, Casilla 298–V, Santiago (Chile)

    2015-11-27

    Properties of the motion of electrically charged particles in the background of the Gibbons–Maeda–Garfinkle–Horowitz–Strominger black hole is presented in this paper. Radial and angular motions are studied analytically for different values of the fundamental parameter. Therefore, gravitational Rutherford scattering and Keplerian orbits are analyzed in detail. Finally, this paper complements previous work by Fernando for null geodesics (Phys Rev D 85:024033, 2012), Olivares and Villanueva (Eur Phys J C 73:2659, 2013) and Blaga (Automat Comp Appl Math 22:41–48, 2013; Serb Astron 190:41, 2015) for time-like geodesics.

  13. Gravitational Rutherford scattering and Keplerian orbits for electrically charged bodies in heterotic string theory

    Energy Technology Data Exchange (ETDEWEB)

    Villanueva, J.R. [Universidad de Valparaiso, Instituto de Fisica y Astronomia, Valparaiso (Chile); Centro de Astrofisica de Valparaiso, Valparaiso (Chile); Olivares, Marco [Universidad Diego Portales, Avenida Ejercito Libertador 441, Facultad de Ingenieria, Santiago (Chile)

    2015-11-15

    Properties of the motion of electrically charged particles in the background of the Gibbons-Maeda-Garfinkle-Horowitz-Strominger black hole is presented in this paper. Radial and angular motions are studied analytically for different values of the fundamental parameter. Therefore, gravitational Rutherford scattering and Keplerian orbits are analyzed in detail. Finally, this paper complements previous work by Fernando for null geodesics (Phys Rev D 85:024033, 2012), Olivares and Villanueva (Eur Phys J C 73:2659, 2013) and Blaga (Automat Comp Appl Math 22:41-48, 2013; Serb Astron 190:41, 2015) for time-like geodesics. (orig.)

  14. Cryptanalysis and Improvement on "Robust EPR-Pairs-Based Quantum Secure Communication with Authentication Resisting Collective Noise"

    Science.gov (United States)

    Yue, Qiu-Ling; Yu, Chao-Hua; Liu, Bin; Wang, Qing-Le

    2016-05-01

    Recently, Chang et al. [Sci Chin-Phys Mech Astron. 57(10), 1907-1912, 2014] proposed two robust quantum secure communication protocols with authentication based on Einstein-Podolsky-Rosen (EPR) pairs, which can resist collective noise. In this paper, we analyze the security of their protocols, and show that there is a kind of security flaw in their protocols. By a kind of impersonation attack, the eavesdropper can obtain half of the message on average. Furthermore, an improved method of their protocols is proposed to close the security loophole.

  15. OBSERVATION OF SPACE DEBRIS IN TARIJA’S OBSERVATORY, BOLIVIA IN THE FRAME OF THE PROGRAM ISON (INTERNATIONAL SCIENTIFIC OPTICAL NETWORK)

    OpenAIRE

    R. Zalles Barrera; Molotov, I.; Agapov, V.

    2014-01-01

    El Observatorio Astron ́mico Nacional de Tarija, Bolivia con los telescopios que cuenta y en cooperaci ́n con o o la Red Internacional (ISON) en septiembre y octubre de 2005 llevaron a cabo observaciones experimentales de detecci ́n de basura espacial en la ́rbita m ́s poblada, la geoestacionaria, debido al mayor n ́mero de sat ́lites o o a u e que se han puesto en ́rbita. A partir de octubre de 2006 se realizan observaciones regulares con el Astr ́grafo o o de 23 cm y c ́mara CCD; posterio...

  16. Comment on "Limits on the Time Variation of the Electromagnetic Fine-Structure Constant in the Low Energy Limit from Absorption Lines in the Spectra of Distant Quasars"

    CERN Document Server

    Murphy, Michael T; Flambaum, Victor V

    2007-01-01

    In their Letter [Phys. Rev. Lett. 92, 121302 (2004)] (also [Astron. Astrophys. 417, 853 (2004)]), Srianand et al. analysed optical spectra of heavy-element species in 23 absorption systems along background quasar sight-lines, reporting limits on relative variations in the fine-structure constant: da/a=(-0.06+/-0.06) x 10^{-5}. Here we demonstrate basic flaws in their analysis, using the same data and absorption profile fits, which led to spurious values of da/a and significantly underestimated uncertainties. We conclude that these data and fits offer no stringent test of previous evidence for a varying alpha.

  17. Herramientas libres para modelar software Free tools to model software

    Directory of Open Access Journals (Sweden)

    Mauro Callejas Cuervo Óscar Yovany Baquero Moreno

    2010-11-01

    Full Text Available Observación acerca del  software libre y de suimplicación en procesos de desarrollo de  softwarecon herramientas 4G por parte de entidades opersonas sin capitales astronómicos y sin lamentalidad acaparadora de dominar el mercado conproductos costosos que las hagan multimillonarias yque no ofrecen una garantía real, ni la posibilidadsiquiera de conocer el  software por el que se hapagado, y mucho menos de modificarlo si no cumplenuestras expectativas.

  18. Eventos Planetarios Periodicos

    Science.gov (United States)

    Flores Gutierrez, J. D.

    1987-05-01

    El análisis de las coordenadas ecuatoriales para los planetas Mercurio, Venus, Marte, Júpiter, Saturno, en los instantes en que ocurren algunos eventos astronómicos, como conjunciones, oposiciones,etc., muestra un comportamiento periódico, característico a cada planeta. El caso de Venus es el mejor estudiado. El cálculo de las efemérides a lo largo de 1000 años , indica un período característico de aproximadamente 260 años. Resultados preliminares con otros planetas muestran períodos distintos.

  19. Tidal mechanism as an impossible cause of the observed secular increase of the astronomical unit

    CERN Document Server

    Itoh, Yousuke

    2009-01-01

    Krasinsky and Brumberg (2004 Celest. Mech. Dyn. Astron., 90, 267) reported a secular increase of the astronomical unit (AU) of 15 meters per century. Recently, Miura et al. (2009, PASJ, 61) proposed that a possible angular momentum transfer from the rotation of the Sun to the orbital motion of the solar system planets may explain the observed increase of the AU. They assumed that the tidal effect between the planets and the Sun is the cause of this transfer. Here we claim that tidal effect cannot be a cause of this type of the transfer to explain the increase of the AU.

  20. COATLI: an all-sky robotic optical imager with 0.3 arcsec image quality

    OpenAIRE

    Alan M. Watson; Cardona, Salvador Cuevas; Núñez, Luis C. Álvarez; Ángeles, Fernando; Becerra-Godínez, Rosa L.; Chapa, Oscar; Farah, Alejandro S.; Fuentes-Fernández, Jorge; Figueroa, Liliana; Lebre, Rosalía Langarica; Quirós, Fernando; Román-Zúñiga, Carlos G.; Ruíz-Diáz-Soto, Jaime; Tejada, Carlos G.; Tinoco, Silvio J.

    2016-01-01

    COATLI will provide 0.3 arcsec FWHM images from 550 to 900 nm over a large fraction of the sky. It consists of a robotic 50-cm telescope with a diffraction-limited fast-guiding imager. Since the telescope is small, fast guiding will provide diffraction-limited image quality over a field of at least 1 arcmin and with coverage of a large fraction of the sky, even in relatively poor seeing. The COATLI telescope will be installed at the at the Observatorio Astron\\'omico Nacional in Sierra San Ped...

  1. It all began with publications in Teixeira´s Journal: some remarks on August Gutzmer

    OpenAIRE

    Malonek, Helmuth R.; Kharlamova, Vera I.

    2010-01-01

    This article emphasizes some moments in the life of the German mathematician August Gutzmer (1860-1924), who started his scientific career 1887 with 3 publications in the Jornal de Sciências Matemáticas e Astronómicas (Teixeira’s Journal) created by the famous Portuguese mathematician Francisco Gomes Teixeira in 1877, and continued to publish therein until the volume of 1897. A brief analysis of the correspondence between both scientists makes clear that among all foreign authors of this journ...

  2. Far-infrared spectroscopy of a lensed starburst: a blind redshift from Herschel

    OpenAIRE

    George, RD; Ivison, RJ; Hopwood, R.; Riechers, DA; Bussmann, RS; Cox, P.; Dye, S.; Krips, M.; Negrello, M.; Neri, R.; Serjeant, S; Valtchanov, I.; Baes, Maarten; Bourne, N.; Clements, DL

    2013-01-01

    We report the redshift of HATLAS J132427.0+284452 (hereafter HATLAS J132427), a gravitationally lensed starburst galaxy, the first determined 'blind' by the Herschel Space Observatory. This is achieved via the detection of [C II] consistent with z = 1.68 in a far-infrared spectrum taken with the SPIRE Fourier Transform Spectrometer (FTS). We demonstrate that the [C II] redshift is secure via detections of CO J = 2 -> 1 and 3 -> 2 using the Combined Array for Research in Millimeter-wave Astron...

  3. Gravitational Rutherford scattering and Keplerian orbits for electrically charged bodies in heterotic string theory

    Science.gov (United States)

    Villanueva, J. R.; Olivares, Marco

    2015-11-01

    Properties of the motion of electrically charged particles in the background of the Gibbons-Maeda-Garfinkle-Horowitz-Strominger black hole is presented in this paper. Radial and angular motions are studied analytically for different values of the fundamental parameter. Therefore, gravitational Rutherford scattering and Keplerian orbits are analyzed in detail. Finally, this paper complements previous work by Fernando for null geodesics (Phys Rev D 85:024033, 2012), Olivares and Villanueva (Eur Phys J C 73:2659, 2013) and Blaga (Automat Comp Appl Math 22:41-48, 2013; Serb Astron 190:41, 2015) for time-like geodesics.

  4. Doppler Tomography of Cataclysmic Variables with a 6.5-m class Telescope

    OpenAIRE

    Echevarría, J.

    2007-01-01

    Se est llevando a cabo un proyecto a largo plazo de espectroscop a de alta dispersi n (R 20000) para observar y analizar una muestra de variables catacl smicas con el telescopio de 2.1-m en el Observatorio Astron mico Nacional en San Pedro M rtir y el espectr grafo echelle. La herramienta principal para este an lisis es la tomograf a Doppler. En esta contribuci n presentamos nuestro trabajo y abordamos la pregunta: >C mo podr amos mejorar este proyecto con un telescopio de clas...

  5. Abundancias químicas de dos binarias de HgMn

    Science.gov (United States)

    Gonzalez, E. J.; González, J. F.; Collado, A. E.

    We present the results of the abundance analysis of two HgMn single-line binary systems: NGC 2287-106 and NGC 6025-14. The spectroscopic ob- servations have been carried out at the Complejo Astronómico el Leon-cito (CASLEO) with the REOSC spectrograph in cross-dispersion mode, cov- ering the spectral range 3800-5800 ≈. Compared to the Sun, NGC 6025-14 shows great overabundances of Hg, Mn, P, Ga and Xe, while Hg, Mn, Sr, Pt and Zr are overabundant in NGC 2287-106. FULL TEXT IN SPANISH

  6. Specification of APERTIF Polyphase Filter Bank in CλaSH

    OpenAIRE

    Wester, R.; Sarakiotis, D.; Kooistra, E.; Kuper, J.

    2012-01-01

    CλaSH, a functional hardware description language based on Haskell, has several abstraction mechanisms that allow a hardware designer to describe architectures in a short and concise way. In this paper we evaluate CλaSH on a complex DSP application, a Polyphase Filter Bank as it is used in the ASTRON APERTIF project. The Polyphase Filter Bank is implemented in two steps: first in Haskell as being close to a standard mathematical specification, then in CλaSH which is derived from the Haskell f...

  7. Kinematics of yso molecular hydrogen outflows

    Directory of Open Access Journals (Sweden)

    Luis Salas

    2002-01-01

    Full Text Available Describimos observaciones de la l nea de 2.12 m de H2 para los ujos moleculares en OMC-1, HH 211, HH 212, DR21, CephA, y S187-IR, que forman parte de un cat alogo de cinem atica en H2 en preparaci on. Las observaciones est an siendo realizadas con la c amara infrarroja CAMILA y un etal on Fabry-P erot en el telescopio de 2.12 m en el Observatorio Astron omico Nacional en San Pedro M artir. Con una resoluci on espectral de 22 km s...

  8. Herramientas libres para modelar software Free tools to model software

    OpenAIRE

    Mauro Callejas Cuervo Óscar Yovany Baquero Moreno

    2010-01-01

    Observación acerca del  software libre y de suimplicación en procesos de desarrollo de  softwarecon herramientas 4G por parte de entidades opersonas sin capitales astronómicos y sin lamentalidad acaparadora de dominar el mercado conproductos costosos que las hagan multimillonarias yque no ofrecen una garantía real, ni la posibilidadsiquiera de conocer el  software por el que se hapagado, y mucho menos de modificarlo si no cumplenuestras expectativas.

  9. ATMOSPHERIC AEROSOL VARIABILITY OVER THE REGION OF SAN PEDRO MÁRTIR FROM MODIS DATA

    OpenAIRE

    Mario R. Araiza Quijano; Irene Cruz-González

    2011-01-01

    Se presenta un estudio del espesoróptico del aerosol atmosférico (AOT por sus siglas en inglés) en el sitio astronómico de San Pedro Mártir, B. C., México durante el periodo 2000-2008. Las mediciones del AOT se realizaron con el instrumento Moderate Resolution Imaging Spectroradiometer (MODIS), a bordo de los satélites Aqua y Terra de la NASA. Se han identificado valores característicos estacionales que muestran un comportamiento de mayor transparencia atmosférica durante el otoño. Las mejore...

  10. Finite element modeling methods for photonics

    CERN Document Server

    Rahman, B M Azizur

    2013-01-01

    The term photonics can be used loosely to refer to a vast array of components, devices, and technologies that in some way involve manipulation of light. One of the most powerful numerical approaches available to engineers developing photonic components and devices is the Finite Element Method (FEM), which can be used to model and simulate such components/devices and analyze how they will behave in response to various outside influences. This resource provides a comprehensive description of the formulation and applications of FEM in photonics applications ranging from telecommunications, astron

  11. Cryptanalysis and Improvement on "Robust EPR-Pairs-Based Quantum Secure Communication with Authentication Resisting Collective Noise"

    Science.gov (United States)

    Yue, Qiu-Ling; Yu, Chao-Hua; Liu, Bin; Wang, Qing-Le

    2016-10-01

    Recently, Chang et al. [Sci Chin-Phys Mech Astron. 57(10), 1907-1912, 2014] proposed two robust quantum secure communication protocols with authentication based on Einstein-Podolsky-Rosen (EPR) pairs, which can resist collective noise. In this paper, we analyze the security of their protocols, and show that there is a kind of security flaw in their protocols. By a kind of impersonation attack, the eavesdropper can obtain half of the message on average. Furthermore, an improved method of their protocols is proposed to close the security loophole.

  12. Educación no formal

    Science.gov (United States)

    Tignanelli, H.

    Se comentan en esta comunicación, las principales contribuciones realizadas en el campo de la educación en astronomía en los niveles primario, secundario y terciario, como punto de partida para la discusión de la actual inserción de los contenidos astronómicos en los nuevos contenidos curriculares de la EGB - Educación General Básica- y Polimodal, de la Reforma Educativa. En particular, se discuten los alcances de la educación formal y no formal, su importancia para la capacitación de profesores y maestros, y perspectivas a futuro.

  13. Titan's rotational state : The effects of a forced "free" resonant wobble

    OpenAIRE

    Noyelles, B.

    2007-01-01

    In Noyelles et al. (2008, Astron. Astrophys., 478, 959-970), a resonance involving the wobble of Titan is hinted. This paper studies this scenario and its consequences. The first step is to build an accurate analytical model that would help to find the likely resonances in the rotation of every synchronous body. In this model, I take the orbital eccentricity of the body into account, as well as its variable inclination with respect to Saturn's equator. Then an analytical study using the secon...

  14. Matemática aplicada y relaciones de proporcionalidad

    OpenAIRE

    Ros, Rosa María

    1996-01-01

    En el presente artículo se considera el tema de la proporcionalidad en distintos niveles y dentro de ámbitos diferentes. En primer lugar, se trata la proporción en el campo de las ecuaciones mediante unos ejemplos extraídos de la historia de las matemáticas. En segundo lugar, se presentan ejemplos relativos a las proporciones en temas de geometría plana y medida de ángulos dentro de un contexto astronómico. En dicho marco, se elabora una maqueta del sistema solar y, posteriormente, se estudia...

  15. Galileo y los telescopios

    OpenAIRE

    Vela Herranz, Nacho

    2010-01-01

    El proyecto “Galileo y los telescopios” consiste en la realización de un documental muy sintetizado sobre los descubrimientos astronómicos de Galileo Galilei y su invención del telescopio. A lo largo del documental veremos cómo una serie de recursos audiovisuales como lo son la animación 3D, la animación 2D y los efectos especiales, son utilizados para crear esta brevísima historia de cómo fue el origen de la astronomía moderna. Y ésta es precisamente, su brevedad, la baza de este docum...

  16. COATLI: an all-sky robotic optical imager with 0.3 arcsec image quality

    CERN Document Server

    Watson, Alan M; Núñez, Luis C Álvarez; Ángeles, Fernando; Becerra-Godínez, Rosa L; Chapa, Oscar; Farah, Alejandro S; Fuentes-Fernández, Jorge; Figueroa, Liliana; Lebre, Rosalía Langarica; Quirós, Fernando; Román-Zúñiga, Carlos G; Ruíz-Diáz-Soto, Jaime; Tejada, Carlos G; Tinoco, Silvio J

    2016-01-01

    COATLI will provide 0.3 arcsec FWHM images from 550 to 900 nm over a large fraction of the sky. It consists of a robotic 50-cm telescope with a diffraction-limited fast-guiding imager. Since the telescope is small, fast guiding will provide diffraction-limited image quality over a field of at least 1 arcmin and with coverage of a large fraction of the sky, even in relatively poor seeing. The COATLI telescope will be installed at the at the Observatorio Astron\\'omico Nacional in Sierra San Pedro M\\'artir, M\\'exico, during 2016 and the diffraction-limited imager will follow in 2017.

  17. MIENTRAS TANTO EN LA TIERRA: IRONÍA Y SIMULACRO EN ¡ARRE! HALLEY ¡ARRE!, DE ELVIRA HERNÁNDEZ

    OpenAIRE

    Gonzalo Maier

    2015-01-01

    A partir de la manipulación mediática propiciada por la dictadura chilena durante los meses previos al avistamiento del cometa Halley en 1986, este artículo lee la ironía presente en el poemario ¡Arre! Halley ¡Arre! (1986), de Elvira Hernández, como una estrategia que, por un lado, pretende confirmar a una comunidad fracturada y que, por otro, critica la pretensión dictatorial de asimilar mesiánicamente el éxito de las incipientes políticas neoliberales con avistamientos astronómicos que se a...

  18. Xopan y Tonalco, los colores de las estaciones entre los antiguos nahuas

    OpenAIRE

    Dupey García, Elodie

    2013-01-01

    Note portant sur l’auteur COLORES, LUCES Y ESTACIONES EN LA COSMOVISIÓN NAHUA En las culturas indígenas de México, como en muchas sociedades antiguas y tradicionales, los colores mantienen relaciones esenciales con los elementos del medio ambiente y entre ellos los fenómenos meteorológicos y astronómicos. Esto parece lógico si recordamos que el primer contacto del ser humano con el cromatismo se da en la naturaleza donde se producen deslumbrantes manifestaciones celestes y coloreadas como el ...

  19. Comportamiento de la cromósfera solar en la línea H-alfa durante el período enero/05-agosto/06

    Science.gov (United States)

    Missio, H.; Davoli, D.; Aquilano, R.

    Using the instrument at Observatorio Astronómico Municipal de Rosario (OAMR), we analyze the solar chromospheric activity during the period January/05-August/06. The instrument is a Carl Zeiss refractor telescope of 150 mm aperture and 2250 mm of focal distance with a monochromatic filter in the H-alpha line. We take as proxy for the solar activity the area covered by chromospheric ``plages''. The measurements are done using photographic registers. We describe our technique and the results obtained. We observe a decrease of solar activity that corresponds to the end of cycle 23. FULL TEXT IN SPANISH

  20. Amoeiro: Patrimonio, paisaxe e tempo (exposición permanente)

    OpenAIRE

    García Quintela, Marco V.; González-García, A. César; González Veiga, Martina; Seoane-Veiga, Yolanda; Rodríguez-Paz, Anxo

    2010-01-01

    [GA] Amosamos os contidos expositivos da mostra permanente adicada ao patrimonio cultural na zona dos Chaos de Amoeiro, Ourense. Nesta exposición faise referencia á disciplina da arqueoastronomía, é dicir, aos fenómenos astronómicos asociados aos restos arqueolóxicos, neste caso a través do exemplo de Amoeiro. Ademais descríbese, por unha banda, a traxectoria da investigación arqueolóxica e patrimonial desenvolta na zona polo equipo de científicos/as do Laboratorio de Patrimonio, Paleoambient...

  1. Measurement of Physical Libration of Enceladus and its Interpretation

    Science.gov (United States)

    Thomas, P. C.; Tiscareno, M. S.; Burns, J. A.; Tajeddine, R.; Joseph, J.; Porco, C.

    2014-12-01

    Enceladus' interior structure [1] plays a critical role in understanding the composition and activity of the satellite's south polar geysers [2,3] and in interpreting its tectonic activity. Enceladus' physical rotational libration, a periodic wobble superposed upon its synchronous rotation and driven by the torques resulting from the satellite's slightly elliptical orbit, provides a means of constraining the interior structure. We use stereogrammetric solutions of control points of Enceladus in Cassini images to test rotation states, calculating the change in the control-point model's goodness of fit as we vary the predicted physical libration amplitude, and thus constraining Enceladus' moments of inertia. Our analysis of over 5300 measurements in 340 images indicates a physical libration amplitude of 0.11 deg. This libration amplitude is not consistent with a solid hydrostatic body (for which the amplitude should be about 0.04 deg), but would be consistent with some versions of recent models incorporating global subsurface oceans or non-hydrostatic cores. We will report on our continuing analysis and on the consistency of interior models with the observed physical libration. References. [1] Iess, L. et al. (2014) Science, 344, 78-80. [2] Porco, C. et al. (2014) Astron. J. 148,45. [3] Nimmo, F. et al. (2014) Astron. J. 148,46.

  2. The cycling of carbon into and out of dust

    CERN Document Server

    Jones, Anthony P; Koehler, Melanie; Fanciullo, Lapo; Bocchio, Marco; Micelotta, Elisabetta; Verstraete, Laurent; Guillet, Vincent

    2014-01-01

    Observational evidence seems to indicate that the depletion of interstellar carbon into dust shows rather wide variations and that carbon undergoes rather rapid recycling in the interstellar medium (ISM). Small hydrocarbon grains are processed in photo-dissociation regions by UV photons, by ion and electron collisions in interstellar shock waves and by cosmic rays. A significant fraction of hydrocarbon dust must therefore be re-formed by accretion in the dense, molecular ISM. A new dust model (Jones et al., Astron. Astrophys., 2013, 558, A62) shows that variations in the dust observables in the diffuse interstellar medium (nH = 1000 cm^3), can be explained by systematic and environmentally-driven changes in the small hydrocarbon grain population. Here we explore the consequences of gas-phase carbon accretion onto the surfaces of grains in the transition regions between the diffuse ISM and molecular clouds (e.g., Jones, Astron. Astrophys., 2013, 555, A39). We find that significant carbonaceous dust re-processi...

  3. Study of the Local Horizon. (Spanish Title: Estudio del Horizonte Local.) Estudo do Horizonte Local

    Science.gov (United States)

    Ros, Rosa M.

    2009-12-01

    The study of the horizon is fundamental to easy the first observations of the students at any education center. A simple model, to be developed in each center, allows to easy the study and comprehension of the rudiments of astronomy. The constructed model is presented in turn as a simple equatorial clock, other models (horizontal and vertical) may be constructed starting from it. El estudio del horizonte es fundamental para poder facilitar las primeras observaciones de los alumnos en un centro educativo. Un simple modelo, que debe realizarse para cada centro, nos permite facilitar el estudio y la comprensión de los primeros rudimentos astronómicos. El modelo construido se presenta a su vez como un sencillo modelo de reloj ecuatorial y a partir de él se pueden construir otros modelos (horizontal y vertical). O estudo do horizonte é fundamental para facilitar as primeiras observações dos alunos num centro educativo. Um modelo simples, que deve ser feito para cada centro, permite facilitar o estudo e a compreensão dos primeiros rudimentos astronômicos. O modelo construído apresenta-se, por sua vez, como um modelo simples de relógio equatorial e a partir dele pode-se construir outros modelos (horizontal e vertical)

  4. Ajuste de parámetros libres en teorías de campos camaleones a partir de espectros de nubes moleculares galácticas y experimentos terrestres

    Science.gov (United States)

    Teppa Pannia, F. A.; Landau, S. J.

    Resultados recientes, basados en el análisis de espectros moleculares de nubes galácticas a través del método del amoníaco, han arrojado nuevos límites sobre la variación del parámetro adimensional μ=m_e /m_p. Los resultados indican Δ μ/μ = (μ_{obs}-μ_{lab})/μ_{lab}= (2.2± 0.4_{est} ±0.3_{sist}) times 10 ^{-8}, en acuerdo con una variación no nula de dicha cantidad (Levshakov et al. 2010). En este trabajo, motivado por los datos astronómicos, estudiamos la solución lineal del modelo teórico fenomenológico de campo escalar camaleón, presentado por Mota y Shaw (2007), que predice variaciones en μ. Con el fin de cotejar estas predicciones con los resultados observacionales, utilizamos datos de experimentos terrestres que testean violaciones al Principio de Equivalencia para analizar el valor de los parámetros libres presentes en el modelo. El trabajo realizado muestra que la solución estudiada no se puede ajustar a los datos experimentales, sugiriendo que el modelo lineal debe ser descartado para explicar las observaciones astronómicas. FULL TEXT IN SPANISH

  5. From speckle measurements to computation of the binary system orbits at the Astronomical Observatory R. M. Aller

    Directory of Open Access Journals (Sweden)

    M. Andrade

    2006-01-01

    Full Text Available La cámara speckle ICCD, propiedad del Observatorio Astronómico R. M. Aller, ya ha sido usada acoplada al telescopio español de 1.2-m del Observatorio Hispano-Alemán de Calar Alto (Almería, España y se espera usar, próximamente, acoplándola al telescopio alemán de 3.5-m. Las observaciones de casi trescientas estrellas dobles y múltiples que ya se han obtenido con este instrumento están siendo analizadas en el Observatorio Astronómico R. M. Aller. La unión de estas mediciones con otras de épocas anteriores está permitiendo calcular orbitas o mejorar las ya existentes, haciendo uso del método de Docobo para el caso de sistemas binarios. Aquí presentamos una muestra de ello, incluyendo la estimación de masas para algunos sistemas interesantes.

  6. Soft x-ray spectra and collisional ionization equilibrium of iron ions with data upgrade of electron-ion collisions

    Science.gov (United States)

    Liang, G. Y.; Wei, H. G.; Zhao, G.; Zhong, J. Y.

    2016-06-01

    Line emissivities and ionic fraction in (non-)equilibrium are crucial for understanding the x-ray and extreme ultraviolet (EUV) spectra. These emission originate from electron-impact excitations for a level population of highly charged ions in coronal-like plasma. Recently, a large amount of excitation data was generated within the R-matrix framework by the computational atomic physics community, especially the UK APAP network. These data take resonances in electron-ion collisions into account appropriately, which enhances the effective excitation rates and also the line emissivities in x-ray and EUV regions. For ionization equilibrium data, the earlier compilation by Mazzotta et al (1998 Astron. Astrophys. Supp. Ser. 133 403) was used extensively by the astronomical community until the update by Bryans et al (2006 Astrophys. J. Supp. Ser. 167 343), as well as the compilation of Dere (2007 Astron. Astrophys. 466 771) for electron-impact ionization rates. In past years, many experimental measurements have been performed of highly charged iron ions in heavy-ion storage ring facilities. In this work, we will investigate the line emissivities and ionization equilibrium of highly charged iron ions by using recent theoretical or experimental data of electron-impact excitations and ionizations.

  7. On large and small tidal lags. The virtual identity of two rheophysical theories

    CERN Document Server

    Ferraz-Mello, Sylvio

    2015-01-01

    The aim of this letter is to discuss the virtual identity of two recent tidal theories: the creep tide theory of Ferraz-Mello (Cel. Mech. Dyn. Astron. 116, 109, 2013) and the Maxwell model developed by Correia et al. (Astron. Astrophys. 571, A50, 2014). It includes the discussion of the basic equations of the theories, which, in both cases, include an elastic and an anelastic component, and shows that the basic equations of the two theories are equivalent and differ by only a numerical factor in the anelastic tide. It also includes a discussion of the lags: the lag of the full tide (geodetic), dominated by the elastic component, and the phase of the anelastic tide. In rotating rocky bodies not trapped in a spin-orbit resonance (e.g., the Earth) the geodetic lag is close to zero and the phase of the anelastic tide is close to 90 degrees. The results obtained from combining tidal solutions from satellite tracking data and from Topex/Poseidon satellite altimeter data, by Ray et al., are extended to determine the...

  8. Dynamics of accretion disks in a constant curvature f(R)-gravity

    Science.gov (United States)

    Alipour, N.; Khesali, A. R.; Nozari, K.

    2016-07-01

    So far the basic physical properties of matter forming a thin accretion disc in the static and spherically symmetric space-time metric of the vacuum f(R) modified gravity models (Pun et al. in Phys. Rev. D 78:024043, 2008) and building radiative models of thin accretion disks for both Schwarzschild and Kerr black holes in f(R) gravity (Perez et al. in Astron. Astrophys. 551:4, 2013) were addressed properly. Also von Zeipel surfaces and convective instabilities in f(R)-Schwarzschild(Kerr) background have been investigated recently (Alipour et al. in Mon. Not. R. Astron. Soc. 454:1992, 2015). In this streamline, here we study the effects of radial and angular pressure gradients on thick accretion disks in Schwarzschild geometries in a constant curvature f(R) modified gravity. Since thick accretion disks have high accretion rate, we study configuration and structure of thick disks by focusing on the effect of pressure gradient on formation of the disks. We clarify our study by assuming two types of equation of state: polytropic and Clapeyron equation of states.

  9. Solutions of the Einstein's field equations with anisotropic pressure compatible with cold star model

    Science.gov (United States)

    Singh, Ksh. Newton; Bhar, Piyali; Pant, Neeraj

    2016-10-01

    In this paper we obtain a new static and spherically symmetric model of compact star whose spacetime satisfies Karmarkar's condition (1948). The Einstein's field equations are solved by employing a physically reasonable choice of the metric coefficient g_{rr} so that the obtained solution is free from central singularities. Our model satisfies all the energy conditions as well as the causality condition. By assigning some particular values mass and radius of the compact stars PSR J0347+0432, Cen X-3 and Vela X-1 have been obtained which are very close to the observational data proposed by Antoniadis et al. (Science 340:1233232, 2013), Abubekerov et al. (Astron. Rep. 48:89, 2004) and Ash et al. (Mon. Not. R. Astron. Soc. 307:357, 1999). For the neutron star candidate PSR J0348+0432, we expect a very stiff equation of state to support its massive mass which corresponds to a large value of the adiabatic index of 6.66 at the center.

  10. Soft x-ray spectra and collisional ionization equilibrium of iron ions with data upgrade of electron–ion collisions

    Science.gov (United States)

    Liang, G. Y.; Wei, H. G.; Zhao, G.; Zhong, J. Y.

    2016-06-01

    Line emissivities and ionic fraction in (non-)equilibrium are crucial for understanding the x-ray and extreme ultraviolet (EUV) spectra. These emission originate from electron-impact excitations for a level population of highly charged ions in coronal-like plasma. Recently, a large amount of excitation data was generated within the R-matrix framework by the computational atomic physics community, especially the UK APAP network. These data take resonances in electron–ion collisions into account appropriately, which enhances the effective excitation rates and also the line emissivities in x-ray and EUV regions. For ionization equilibrium data, the earlier compilation by Mazzotta et al (1998 Astron. Astrophys. Supp. Ser. 133 403) was used extensively by the astronomical community until the update by Bryans et al (2006 Astrophys. J. Supp. Ser. 167 343), as well as the compilation of Dere (2007 Astron. Astrophys. 466 771) for electron-impact ionization rates. In past years, many experimental measurements have been performed of highly charged iron ions in heavy-ion storage ring facilities. In this work, we will investigate the line emissivities and ionization equilibrium of highly charged iron ions by using recent theoretical or experimental data of electron-impact excitations and ionizations.

  11. Calibrating the Decline Rate - Peak Luminosity Relation for Type Ia Supernovae

    Science.gov (United States)

    Rust, Bert W.; Pruzhinskaya, Maria V.; Thijsse, Barend J.

    2015-08-01

    The correlation between peak luminosity and rate of decline in luminosity for Type I supernovae was first studied by B. W. Rust [Ph.D. thesis, Univ. of Illinois (1974) ORNL-4953] and Yu. P. Pskovskii [Sov. Astron., 21 (1977) 675] in the 1970s. Their work was little-noted until Phillips rediscovered the correlation in 1993 [ApJ, 413 (1993) L105] and attempted to derive a calibration relation using a difference quotient approximation Δm15(B) to the decline rate after peak luminosity Mmax(B). Numerical differentiation of data containing measuring errors is a notoriously unstable calculation, but Δm15(B) remains the parameter of choice for most calibration methods developed since 1993. To succeed, it should be computed from good functional fits to the lightcurves, but most workers never exhibit their fits. In the few instances where they have, the fits are not very good. Some of the 9 supernovae in the Phillips study required extinction corrections in their estimates of the Mmax(B), and so were not appropriate for establishing a calibration relation. Although the relative uncertainties in his Δm15(B) estimates were comparable to those in his Mmax(B) estimates, he nevertheless used simple linear regression of the latter on the former, rather than major-axis regression (total least squares) which would have been more appropriate.Here we determine some new calibration relations using a sample of nearby "pure" supernovae suggested by M. V. Pruzhinskaya [Astron. Lett., 37 (2011) 663]. Their parent galaxies are all in the NED collection, with good distance estimates obtained by several different methods. We fit each lightcurve with an optimal regression spline obtained by B. J. Thijsse's spline2 [Comp. in Sci. & Eng., 10 (2008) 49]. The fits, which explain more that 99% of the variance in each case, are better than anything heretofore obtained by stretching "template" lightcurves or fitting combinations of standard lightcurves. We use the fits to compute estimates of

  12. On the dark matter as a geometric effect in f (R) gravity

    Science.gov (United States)

    Usman, Muhammad

    2016-11-01

    A mysterious type of matter is supposed to exist because the observed rotational velocity curves of particles moving around the galactic center and the expected rotational velocity curves do not match. This type of matter is called dark matter. There are also a number of proposals in the modified gravity which are alternatives to the dark matter. In this contrast, in 2008, Christian G. Böhmer, Tiberiu Harko and Francisco S.N. Lobo presented an interesting idea in Böhmer et al. (Astropart Phys 29(6):386-392, 2008) where they showed that a f (R) gravity model could actually explain dark matter to be a geometric effect only. They solved the gravitational field equations in vacuum using generic f (R) gravity model for constant velocity regions (i.e. dark matter regions around the galaxy). They found that the resulting modifications in the Einstein Hilbert Lagrangian is of the form R^{1+m}, where m=V_{tg}^2/c^2; V_{tg} being the tangential velocity of the test particle moving around the galaxy in the dark matter regions and c being the speed of light. From observations it is known that m≈ O(10^{-6}) (Böhmer et al. 2008; Salucci et al. in Mon Not R Astron Soc 378(1):41-47, 2007; Persic et al. in Mon Not R Astron Soc 281:27-47, 1996; Borriello and Salucci in Mon Not R Astron Soc 323(2):285-292, 2001). In this article, we perform two things (1) We show that the form of f (R) they claimed is not correct. In doing the calculations, we found that when the radial component of the metric for constant velocity regions is a constant then the exact solutions for f (R) obtained is of the form of R^{1-α } which corresponds to a negative correction rather than positive claimed by the authors of Böhmer et al. (2008), where α is the function of m. (2) We also show that we can not have an analytic solution of f(R) for all values of tangential velocity including the observed value of tangential velocity 200-300 km/s (Salucci et al. 2007; Persic et al. 1996; Borriello and Salucci

  13. Constraints on the Bulk Composition of Uranus from Herschel PACS and ISO LWS Photometry, SOFIA FORCAST Photometry and Spectroscopy, and Ground-Based Photometry of its Thermal Emission

    Science.gov (United States)

    Orton, Glenn; Mueller, Thomas; Burgdorf, Martin; Fletcher, Leigh; de Pater, Imke; Atreya, Sushil; Adams, Joseph; Herter, Terry; Keller, Luke; Sidher, Sunil; Sinclair, James; Fujiyoshi, Takuya

    2016-04-01

    We present thermal infrared observations of the disk of Uranus at 17-200 μm to deduce its global thermal structure and bulk composition. We combine 17-200 μm filtered photometric measurements by the Herschel PACS and ISO LWS instruments and 19-35 μm filtered photometry and spectroscopy by the SOFIA FORCAST instrument, supplemented by 17-25 μm ground-based photometric filtered imaging of Uranus. Previous analysis of infrared spectroscopic measurements of the disk of Uranus made by the Spitzer IRS instrument yielded a model for the disk-averaged temperature profile and stratospheric composition (Orton et al. 2014a Icarus 243,494; 2014b Icarus 243, 471) that were consistent with submillimeter spectroscopy by the Herschel SPIRE instrument (Swinyard et al. 2014, MNRAS 440, 3658). Our motivation to observe the 17-35 μm spectrum was to place more stringent constraints on the global para-H2 / ortho-H2 ratio in the upper troposphere and lower stratosphere than the ISO SWS results of Fouchet et al. (2003, Icarus 161, 127), who examined H2 quadrupole lines. We will discuss the consistency of these observations with a higher para-H2 fraction than implied by local thermal equilibrium, which would resolve a discrepancy between the Spitzer-based model and observations of HD lines by the Herschel PACS experiment (Feuchtgruber et al. 2013 Astron. & Astrophys. 551, A126). Constraints on the global para-H2 fraction allow for more precise analysis of the far-infrared spectrum, which is sensitive to the He:H2 ratio, a quantity that was not constrained by the Spitzer IRS spectra. The derived model, which assumed the ratio derived by the Voyager-2 IRIS/radio-science occultation experiment (Conrath et al. 1987 J. Geophys. Res. 92, 15003), is inconsistent with 70-200 μm PACS photometry (Mueller et al. 2016 Astron. & Astrophys. submittted) and ISO LWS photometric measurements. However, the model can be made consistent with the observations if the fraction of He relative to H2 were

  14. Theoretical calculation of photoionization cross sections of B-like ions: N2+,O3+ and F4+

    Institute of Scientific and Technical Information of China (English)

    Wang Guo-Li; Zhou Xiao-Xin

    2009-01-01

    There can be found some notable discrepancies with regard to the resonance structures when R-matrix calculations from the Opacity Project and other sources are compared with recent absolute experimental measurements of Bizau et al [Astron. Astrophts. 439 387 (2005)] for B-like ions N2+,03+ and F4+. We performed close-coupling calculatious based on the R-matrix formalism for the photoionizations of ions mentioned above both for the ground states and first excited states in the near threshold regions. The present results are compared with experimental ones given by Bizau et al and earlier theoretical ones. Excellent agreement is obtained between our theoretical results and the experimental photoionization cross sections. The present calculations show a significant improvement over the previous theoretical results.

  15. Stellar Archaeology and Galaxy Genesis: The Need for Large Area Multi-Object Spectrograph on 8 m-Class Telescopes

    Science.gov (United States)

    Irwin, Mike J.; Lewis, Geraint F.

    The origin and evolution of galaxies like the Milky Way and M31 remain among the key questions in astrophysics. The galaxies we see today in and around the Local Group are representatives of the general field population of the Universe and have been evolving for the majority of cosmic time. As our nearest neighbour systems they can be studied in far more detail than their distant counterparts and hence provide our best hope for understanding star formation and prototypical galaxy evolution over the lifetime of the Universe [K. Freeman, J. Bland-Hawthorn in Annu. Rev. Astron. Astrophys. 40, 487 (2002)]. Significant observational progress has been made, but we are still a long way from understanding galaxy genesis. To unravel this formative epoch, detailed large area multi-object spectroscopy of spatial, kinematic and chemical structures on 8 m-class telescopes are required, to provide the link between local near-field cosmology and predictions from the high-redshift Universe.

  16. Atlas of monochromatic images of planetary nebulae

    CERN Document Server

    Weidmann, W A; Valdarenas, R R Vena; Ahumada, J A; Volpe, M G; Mudrik, A

    2016-01-01

    We present an atlas of more than one hundred original images of planetary nebulae (PNe). These images were taken in a narrow-band filter centred on the nebular emission of the [N II] during several observing campaigns using two moderate-aperture telescopes, at the Complejo Astron\\'omico El Leoncito (CASLEO), and the Estaci\\'on Astrof\\'isica de Bosque Alegre (EABA), both in Argentina. The data provided by this atlas represent one of the most extensive image surveys of PNe in [N II]. We compare the new images with those available in the literature, and briefly describe all cases in which our [N II] images reveal new and interesting structures.

  17. Strategic Plan for Astronomy in the Netherlands 2011-2020

    CERN Document Server

    Groot, P J; Stark, R

    2012-01-01

    Strategic Plan for Astronomy in the Netherlands 2011 - 2020, written by the Netherlands Committee for Astronomy (NCA), on behalf of the excellence research school in astronomy NOVA, (combining the university astronomy institutes of the universities of Amsterdam, Groningen, Leiden and Nijmegen), the NWO division of Physical Sciences, the Netherlands Institute for Radio Astronomy ASTRON and the Netherlands Institute for Space Research SRON. The Strategic plan outlines the scientific priorities for Dutch astronomy in the next decade; the instrumentation effort required to address these priorities, and the connection between astronomical instrumentation and technology development and fundamental technological R&D; the financial contours needed to realise the priorities; and the role of Dutch astronomy in education and outreach. The Strategic Plan also includes a retrospective on the achievements since the last Strategic Plan (2000) and a forward look beyond 2020.

  18. Proyecto para la medición sistemática de seeing en CASLEO

    Science.gov (United States)

    Fernández Lajus, E.; Forte, J. C.

    La calidad del seeing astronómico es ciertamente uno de los parámetros mas importantes que caracterizan el sitio de un observatorio. Por tanto se desea determinar si el alto valor de seeing observado con el telescopio de 2.15 m se debe a efectos internos y/o del entorno a la cupula o si se debe simplemente al seeing propio del lugar. El actual mecanismo de refrigeración del espejo primario del 2.15, parece haber mejorado notablemente la calidad del seeing. Sin embargo se hace necesario saber hasta que punto el valor del seeing puede ser mejorado. La primera etapa del proyecto consistió en la puesta a punto del telescopio emplazado para este propósito y la adquisición de las primeras medidas tentativas de seeing.

  19. El origen de la física moderna : el papel de Fermi

    OpenAIRE

    Hernández Fernández, Antonio

    2014-01-01

    La primera mitad del siglo XX fue crucial para que la ciencia moderna se estableciese tal y como la conocemos. El ser humano extendió su comprensión del mundo tras explorar el mundo atómico y el astronómico. Entender lo inmenso y lo ínfimo permitió desarrollar la tecnología nuclear e inventar nuevos materiales, clave en la revolución electrónica de la segunda mitad del siglo XX. La historia de la ciencia de este periodo fue un auténtico encuentro multidisciplinar en el que la física jugó ...

  20. Application of Three-Dimensional Models for the Teaching of Time Zones. (Breton Title: Aplicação de Modelos Tridimensionais Para o Ensino de Fusos Horários.) Aplicación de Modelos Tridimensionales Para la Enseñanza de Husos Horarios

    Science.gov (United States)

    Azevedo Sobreira, Paulo Henrique

    2012-07-01

    There are several interesting astronomical topics that must be addressed in the High School and Elementary/Middle School in the disciplines of Geography and of Sciences. Among them, the topic of time zones which is one of the most important to understand the correlation of the Earth's rotation and its implications on daily activities of citizens in local scale, regional and global scales which involve problems of time differences. For the teaching of time zones in the lessons of Geography, for example, there are bi-dimensional representations of thematic maps of world time zones, textbooks and atlas. It happens that teachers face some difficulties to permit its students to view three-dimensionally this astronomical phenomenon from the textbooks available in schools. The aim of this paper is to present two proposals with low-cost materials, which allow the preparation of three-dimensional models for the teaching of time zones. Há vários temas astronômicos interessantes que devem ser trabalhados nos Ensinos Médio e Fundamental, nas disciplinas de Geografia e de Ciências. Entre eles, o tema dos fusos horários que é um dos mais importantes para se correlacionar a rotação da Terra e suas implicações nas atividades cotidianas dos cidadãos em escala local, regional e global, que envolvem problemas de diferenças horárias. Para o ensino dos fusos horários nas aulas de Geografia, por exemplo, há representações bidimensionais de mapas temáticos de fusos horários mundiais, nos livros didáticos e nos atlas. Ocorre que os professores enfrentam algumas dificuldades para possibilitar aos seus alunos a visão tridimensional deste fenômeno astronômico, a partir dos materiais didáticos disponíveis nas escolas. O objetivo deste trabalho é apresentar duas propostas para a confecção de materiais de baixo custo, que possibilitem a elaboração de modelos tridimensionais para o ensino dos fusos horários. Hay algunos temas astronómicos interesantes que se

  1. Resonances in rotationally inelastic scattering of NH{sub 3} and ND{sub 3} with H{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Qianli; Dagdigian, Paul J., E-mail: pjdagdigian@jhu.edu [Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218-2685 (United States); Avoird, Ad van der, E-mail: A.vanderAvoird@theochem.ru.nl; Meerakker, Sebastiaan Y. T. van de [Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen (Netherlands); Loreau, Jérôme [Service de Chimie Quantique et Photophysique C. P. 160/09, Université Libre de Bruxelles (ULB), 50 Ave. F. D. Roosevelt, 1050 Brussels (Belgium); Alexander, Millard H., E-mail: mha@umd.edu [Department of Chemistry and Biochemistry and Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742-2021 (United States)

    2015-07-28

    We present theoretical studies on the scattering resonances in rotationally inelastic collisions of NH{sub 3} and ND{sub 3} molecules with H{sub 2} molecules. We use the quantum close-coupling method to compute state-to-state integral and differential cross sections for the NH{sub 3}/ND{sub 3}–H{sub 2} system for collision energies between 5 and 70 cm{sup −1}, using a previously reported potential energy surface [Maret et al., Mon. Not. R. Astron. Soc. 399, 425 (2009)]. We identify the resonances as shape or Feshbach resonances. To analyze these, we use an adiabatic bender model, as well as examination at the scattering wave functions and lifetimes. The strength and width of the resonance peaks suggest that they could be observed in a crossed molecular beam experiment involving a Stark-decelerated NH{sub 3} beam.

  2. Cosmology and the Subgroups of Gamma-ray Bursts

    Directory of Open Access Journals (Sweden)

    A. Mészáros

    2011-01-01

    Full Text Available Both short and intermediate gamma-ray bursts are distributed anisotropically in the sky (Mészáros, A. et al. ApJ, 539, 98 (2000, Vavrek, R. et al. MNRAS, 391, 1 741 (2008. Hence, in the redshift range, where these bursts take place, the cosmological principle is in doubt. It has already been noted that short bursts should be mainly at redshifts smaller than one (Mészáros, A. et al. Gamma-ray burst: Sixth Huntsville Symp., AIP, Vol. 1 133, 483 (2009; Mészáros, A. et al. Baltic Astron., 18, 293 (2009. Here we show that intermediate bursts should be at redshifts up to three.

  3. Infrared Polarization and Beaming Effect for BL Lac Objects

    Institute of Scientific and Technical Information of China (English)

    MEI Dong-Cheng; XIE Guang-Zhong

    2001-01-01

    With the idea of the beaming models, we derive a relation between the observed polarization and Dopplercorrected magnitude; that is, the observed polarization is in anti-correlation with the Doppler-corrected magnitude. Making use of the infrared data observed simultaneously by Impey et al. [Mon. Not. R. Astron. Soc.200 (1982) 19; 209 (1984) 245] and Holmes et al. [ibid. 210 (1984) 961] we found that: (1) there is a significant correlation between the observed maximum polarization and Doppler-corrected magnitude but the polarization is not in anti-correlation with the Doppler-corrected magnitude; (2) the maximum infrared polarization is strongly correlated with the maximum optical polarization. Our conclusion is that the infrared polarization depends only on the degree of ordering of the magnetic field in the synchrotron emission regions and not on the beaming effect.Both infrared and optical emissions originate from the synchrotron radiation.

  4. Segunda discontinuidad de Balmer y procesos físicos en envolturas extendidas de estrellas Be

    Science.gov (United States)

    Bibbo, I.; Cruzado, A.; Ringuelet, A.

    We study a group of Be stars in which the second Balmer jump is observed. Our aim is to correlate the second Balmer jump with other spectral features. Spectroscopic observations were performed with the 2.15 m telescope at Complejo Astronómico el Leoncito, CASLEO (San Juan, Argentina). In December 2001 and August 2002 high resolution echelle spectra were obtained with a REOSC echelle spectrograph. We find that, when a second Balmer jump in emission is observed, an emission in λ = 4233,17 Å of FeII multiplet 27 is also, generally seen. Besides, the electron temperature of the region of the envelope where the second jump is formed is estimated assuming that radiative recombinations cause the flux emission in the Balmer continuum. The temperature values obtained in this way are found correlated with the measure of the second Balmer jump.

  5. The chemistry of stellar Jets

    Directory of Open Access Journals (Sweden)

    D. A. Williams

    2002-01-01

    Full Text Available Se pueden explorar muchos fen omenos astron omicos a trav es de observaciones de la emisi on de l neas molec- ulares. En este art culo discutimos la qu mica que da origen a los trazadores moleculares en dos escenarios asociados con la interacci on de chorros estelares con las nubes moleculares. La primera situaci on es el ambi- ente de un choque de proa cerca a la cabeza de un chorro, el cual est a entrando en una nube molecular. La segunda es el caso de un grumo dentro de una nube molecular, el cual se ve afectado por el campo de radiaci on intensa que se genera en el choque entre el chorro y la nube. En ambos casos, se pueden identi car trazadores moleculares espec cos de las condiciones f sicas.

  6. On the jets, kinks, and spheromaks formed by a planar magnetized coaxial gun

    CERN Document Server

    Hsu, S C

    2004-01-01

    Measurements of the various plasma configurations produced by a planar magnetized coaxial gun provide insight into the magnetic topology evolution resulting from magnetic helicity injection. Important features of the experiments are a very simple coaxial gun design so that all observed geometrical complexity is due to the intrinsic physical dynamics rather than the source shape and use of a fast multiple-frame digital camera which provides direct imaging of topologically complex shapes and dynamics. Three key experimental findings were obtained: (1) formation of an axial collimated jet [Hsu and Bellan, Mon. Not. R. Astron. Soc. 334, 257 (2002)] that is consistent with a magnetohydrodynamic description of astrophysical jets, (2) identification of the kink instability when this jet satisfies the Kruskal-Shafranov limit, and (3) the nonlinear properties of the kink instability providing a conversion of toroidal to poloidal flux as required for spheromak formation by a coaxial magnetized source [Hsu and Bellan, P...

  7. Rigorous estimates for the relegation algorithm

    Science.gov (United States)

    Sansottera, Marco; Ceccaroni, Marta

    2016-07-01

    We revisit the relegation algorithm by Deprit et al. (Celest. Mech. Dyn. Astron. 79:157-182, 2001) in the light of the rigorous Nekhoroshev's like theory. This relatively recent algorithm is nowadays widely used for implementing closed form analytic perturbation theories, as it generalises the classical Birkhoff normalisation algorithm. The algorithm, here briefly explained by means of Lie transformations, has been so far introduced and used in a formal way, i.e. without providing any rigorous convergence or asymptotic estimates. The overall aim of this paper is to find such quantitative estimates and to show how the results about stability over exponentially long times can be recovered in a simple and effective way, at least in the non-resonant case.

  8. The AARTFAAC All Sky Monitor: System Design and Implementation

    CERN Document Server

    Prasad, Peeyush; Kooistra, Eric; van der Schuur, Daniel; Gunst, Andre; Romein, John; Kuiack, Mark; Molenaar, Gijs; Rowlinson, Antonia; Swinbank, John D; Wijers, Ralph A M J

    2016-01-01

    The Amsterdam-ASTRON Radio Transients Facility And Analysis Center (AARTFAAC) all sky monitor is a sensitive, real time transient detector based on the Low Frequency Array (LOFAR). It generates images of the low frequency radio sky with spatial resolution of 10s of arcmin, MHz bandwidths, and a time cadence of a few seconds, while simultaneously but independently observing with LOFAR. The image timeseries is then monitored for short and bright radio transients. On detection of a transient, a low latency trigger will be generated for LOFAR, which can interrupt its schedule to carry out follow-up observations of the trigger location at high sensitivity and resolutions. In this paper, we describe our heterogeneous, hierarchical design to manage the 240 Gbps raw data rate, and large scale computing to produce real-time images with minimum latency. We discuss the implementation of the instrumentation, its performance, and scalability.

  9. Neutrino-pair bremsstrahlung in a neutron star crust

    CERN Document Server

    Ofengeim, D D; Yakovlev, D G

    2014-01-01

    Based on the formalism by Kaminker et al. (Astron. Astrophys. 343 (1999) 1009) we derive an analytic approximation for neutrino-pair bremsstrahlung emissivity due to scattering of electrons by atomic nuclei in the neutron star crust of any realistic composition. The emissivity is expressed through generalized Coulomb logarithm which we fit by introducing an effective potential of electron-nucleus scattering. In addition, we study the conditions at which the neutrino bremsstrahlung in the crust is affected by strong magnetic fields. The results can be applied for modelling of many phenomena in neutron stars, such as thermal relaxation in young isolated neutron stars and in accreting neutron stars with overheated crust in soft X-ray transients.

  10. Wavefront outer scale measurements at San Pedro Mártir observatory. Its impact on adaptive optics performances

    Directory of Open Access Journals (Sweden)

    R. Conan

    2003-01-01

    Full Text Available Se presentan las primeras mediciones de la escala externa de coherencia espacial L0 en el Observatorio Astron omico Nacional de San Pedro M artir, M exico. Dicho par ametro fue medido con el monitor generalizado de seeing de la Universidad de Niza, Francia. Se encuentra una distribuci on log-normal con valor mediano de 27.0 m. La importancia de L0 en la derivaci on del desempe~no de la optica adaptativa (OA es analizada. Se demuestra que valores bajos de L0 incrementan las habilidades correctoras de la OA de bajo orden, pero no tienen pr acticamente ning un efecto en OA de alto orden.

  11. Carbon Chemistry: Effects on Planetesimal Composition in Exoplanetary Systems

    Science.gov (United States)

    Johnson, Torrence; Lunine, Jonathan; Mousis, Olivier; Madhusudhan, Nikku

    2012-07-01

    CHON, if approximately 40% of the total carbon is in CHON. Part of this work (TVJ) has been conducted at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with NASA. Government sponsorship acknowledged. NM acknowledges support from NASA HST and JPL/Spitzer grants. JIL was supported by the James Webb Space Telescope Project through NASA. O.M. acknowledges support from CNES. [1] Gonzales, G., et al.,Astron. J., 2001. 121: p. 432-452. [2] Gaidos, E. J.,Icarus, 2000. 145: p. 637-640. [3] Wong, M. H., et al., in Oxygen in the Solar System, G.J. MacPherson, Editor 2008, Mineralogical Society of America: Chantilly, VA. p. 241-246. [4] Johnson, T. V., J. I. Lunine, and O. Mousis, 42nd LPSC (2011), Abstract #1553, 2011. [5] Bond, J. C., D. P. O'Brien, and D. S. Lauretta, Astrophys. J., 2010. 715: 1050-1070. [6] Ecuvillon, A., et al., Astron. Astrophys., 2004. 426, 61: 619-630. [7] Ecuvillon, A., et al., Astron. Astrophys., 2006. 445: p. 633-645. [8] Gilli, G., et al., Astron. Astrophys., 2006. 449: 723-755. [9] Fossati, L., et al., Astrophys. J., 2010. 720: p. 872-886. [10] Johnson, T. V., et al., Astrophys. J. 2012, submitted.

  12. Specific Angular Momentum Distribution of Disc Galaxies Formed in Preheated Intergalactic Media

    Institute of Scientific and Technical Information of China (English)

    LUO Zhi-Jian; FU Li-Ping; SHU Cheng-Gang

    2004-01-01

    Assuming that baryons within a galactic halo have the same specific angular momentum as the dark matter where they locate initially and a disc forms due to the gas cooling and condensation with the conservation of angular momentum, we investigate the angular momentum distribution in a resulting galactic disc under the new preheated galaxy formation model suggested by Mo and Mao (Mon. Not. R. Astron. Soc. 333 (2002) 768).Compared with the observational results, it can be concluded that the preheated galaxy formation model can match current observations. This model can be a good approach to solve the problems of both the angular momentum catastrophe and the mismatch of angular-momentum profiles in current disc galaxy formation models.

  13. Continuity of the robustness of contextuality of empirical models

    Science.gov (United States)

    Meng, HuiXian; Cao, HuaiXin; Wang, WenHua; Chen, Liang; Fan, Yajing

    2016-10-01

    Recently, the robustness of contextuality (RoC) of an empirical model was discussed in [Sci. China-Phys. Mech. Astron. 59, 640303 (2016)], many important properties of the RoC have been proved except for its boundedness and continuity. The aim of this paper is to find an upper bound for the RoC over all of empirical models and prove that the RoC is a continuous function on the set of all empirical models. Lastly, a relationship between the RoC and the extent of violating the noncontextual inequalities is established for an n-cycle contextual box. This relationship implies that the RoC can be used to quantify the contextuality of n-cycle boxes.

  14. On super-elastic collisions between large-scale magnetized plasmoids in the heliosphere

    CERN Document Server

    Di Vita, Andrea

    2014-01-01

    Recently, a unique collision between two large-scale magnetized plasmoids produced by coronal mass ejections in the heliosphere has been observed (C. Shen et al. Nature 8, 2012). Results suggest that the collision is super-elastic, i.e. the total linear kinetic energy of the two plasmoids after the collision is larger than before the collision, and that an anti-correlation exists, i.e. the lower the initial relative velocity of the plasmoids, the larger the relative increase in total kinetic energy. Following an old suggestion of W. H. Bostick, IEEE Trans. Plasma Science PS-14 703-717 (1986), here we start from first principles, retrieve some results of D. Kagan et al., Mon. Not. R. Astron. Soc. 406 1140-1145 (2010) and S. Ohsaki et al., Ap. J. Lett. 559 L61 (2001) and show that the anti-correlation is just a consequence of Hall magnetohydrodynamics.

  15. International data transfer for space very long baseline interferometry

    Science.gov (United States)

    Wiercigroch, Alexandria B.

    1994-11-01

    Space very long baseline interferometry (SVLBI) experiments using a TDRSS satellite have successfully demonstrated the capability of using spacecraft to extend the effective baseline length of VLBI observations beyond the diameter of the Earth, thereby improving the resolution for imaging of active galactic nuclei at centimeter wavelengths. As a result, two spacecraft dedicated to SVLBI, VSOP (Japan) and RadioAstron (Russia), are scheduled to be launched into high Earth orbit in 1996 and 1997. The success of these missions depends on the cooperation of the international community in providing support from ground tracking stations, ground radio telescopes, and correlation facilities. The timely exchange and monitoring of data among the participants requires a well-designed and automated international data transfer system. In this paper, we will discuss the design requirements, data types and flows, and the operational responsibilities associated with the SVLBI data transfer system.

  16. Universal density profile for cosmic voids.

    Science.gov (United States)

    Hamaus, Nico; Sutter, P M; Wandelt, Benjamin D

    2014-06-27

    We present a simple empirical function for the average density profile of cosmic voids, identified via the watershed technique in ΛCDM N-body simulations. This function is universal across void size and redshift, accurately describing a large radial range of scales around void centers with only two free parameters. In analogy to halo density profiles, these parameters describe the scale radius and the central density of voids. While we initially start with a more general four-parameter model, we find two of its parameters to be redundant, as they follow linear trends with the scale radius in two distinct regimes of the void sample, separated by its compensation scale. Assuming linear theory, we derive an analytic formula for the velocity profile of voids and find an excellent agreement with the numerical data as well. In our companion paper [Sutter et al., arXiv:1309.5087 [Mon. Not. R. Astron. Soc. (to be published)

  17. Alternative approaches to plasma confinement

    Science.gov (United States)

    Roth, J. R.

    1978-01-01

    The paper discusses 20 plasma confinement schemes each representing an alternative to the tokamak fusion reactor. Attention is given to: (1) tokamak-like devices (TORMAC, Topolotron, and the Extrap concept), (2) stellarator-like devices (Torsatron and twisted-coil stellarators), (3) mirror machines (Astron and reversed-field devices, the 2XII B experiment, laser-heated solenoids, the LITE experiment, the Kaktus-Surmac concept), (4) bumpy tori (hot electron bumpy torus, toroidal minimum-B configurations), (5) electrostatically assisted confinement (electrostatically stuffed cusps and mirrors, electrostatically assisted toroidal confinement), (6) the Migma concept, and (7) wall-confined plasmas. The plasma parameters of the devices are presented and the advantages and disadvantages of each are listed.

  18. The internal density distribution of comet 67P/C-G based on 3D models

    Science.gov (United States)

    Jorda, Laurent; Faurschou Hviid, Stubbe; Capanna, Claire; Gaskell, Robert W.; Gutiérrez, Pedro; Preusker, Frank; Scholten, Frank; Rodionov, Sergey; OSIRIS Team

    2016-10-01

    The OSIRIS camera aboard the Rosetta spacecraft observed the nucleus of comet 67P/C-G from the mapping phase in summer 2014 until now. The images have allowed the reconstruction in three-dimension of nucleus surface with stereophotogrammetry (Preusker et al., Astron. Astrophys.) and stereophotoclinometry (Jorda et al., Icarus) techniques. We use the reconstructed models to constrain the internal density distribution based on: (i) the measurement of the offset between the center of mass and the center of figure of the object, and (ii) the assumption that flat areas observed at the surface of the comet correspond to iso-gravity surfaces. The results of our analysis will be presented, and the consequences for the internal structure and formation of the nucleus of comet 67P/C-G will be discussed.

  19. On the Absence of Core Luminosity–Core-Dominance Parameter (C - ) Correlation in Radio Galaxies and BL Lacs

    Indian Academy of Sciences (India)

    J. A. Alhassan; A. A. Ubachukwu; F. C. Odo

    2013-03-01

    We have presented an alternative interpretation for the absence of correlation in the relationship between the core radio power (C) and core-dominance parameter () for a sample of BL Lacs and radio galaxies found in Fan & Zhang (Astron. Astrophys. 407, 899 (2003)). This is contrary to the predictions of the relativistic beaming and radio source orientation models in which the core luminosity is expected to be Doppler-boosted relative to the extended luminosity which is generally assumed to be isotropic. Our analysis of the C - data indicates a strong luminosity selection effect (reminiscent of bright source samples due to Malmquist bias) in the sample. In particular, we showed that a strong C - correlation exists above some redshift cut-off which may correspond to the flux limit of the sample used.

  20. LOFAR and HDF5: Toward a New Radio Data Standard

    CERN Document Server

    Anderson, Kenneth; Baehren, Lars; Griessmeier, Jean-Mathias; Wise, Michael; Renting, Adriaan

    2010-01-01

    For decades now, scientific data volumes have experienced relentless, exponential growth. As a result, legacy astronomical data formats are straining under a burden not conceived when these formats were first introduced. With future astronomical projects ensuring this trend, ASTRON and the LOFAR project are exploring the use of the Hierarchical Data Format, version 5 (HDF5), for LOFAR radio data encapsulation. Most of LOFAR's standard data products will be stored using the HDF5 format. In addition, HDF5 analogues for traditional radio data structures such as visibility data and spectral image cubes are also being developed. The HDF5 libraries allow for the construction of distributed, entirely unbounded files. The nature of the HDF5 format further provides the ability to custom design a data encapsulation format, specifying hierarchies, content and attributes. The LOFAR project has designed several data formats that will accommodate and house all LOFAR data products, the primary styles and kinds of which are ...

  1. Nuevas estrellas preenanas blancas pulsantes de masa extremadamente baja descubiertas en el CASLEO

    Science.gov (United States)

    Corti, M.; Kanaan, A.; Córsico, A. H.; Kepler, S. O.; Althaus, L. G.; Koester, D.; Sánchez Arias, J.

    2016-08-01

    The Extremely Low Mass white dwarfs (ELM, M 0.18--0.20 M) could arise after the loss of large amount of mass suffered by a red giant star in a binary system. The low mass white dwarfs have become an important source of study because some of them are pulsating stars. The latter is an unprecedented opportunity to know their interior and the evolutionary channels leading to their origin, by employing asteroseismology. In this paper, we present photometric analysis of data obtained in the CASLEO (Complejo Astronómico El Leoncito) about four new pulsating stars, that according to their surface gravities and effective temperatures, would be pre-ELM white dwarf stars. With this discovery, the number of pulsating pre-ELM white dwarf stars known would increase to six members.

  2. The use of silicon photomultipliers for very high energy gamma ray astronomy: the optical issues

    Science.gov (United States)

    Cadu, A.; Le Padellec, A.; Jradi, K.; Pellion, D.; Bazer-Bachi, A. R.

    2013-04-01

    Due to its sensitivity and speed, the detector still widely used in Cerenkov astrophysics experiments remains the Photo-Multiplier Tube (PMT). However, there are some disadvantages to the PMT technology: the rather poor quantum efficiency, the use of high voltages, the high cost when used in large number in a matrix arrangement and a subsequent large weight. Hence, we have investigated the possibility to design future Cerenkov telescope cameras based on solid state technology, specifically Geiger Avalanche PhotoDiodes (G-APD's). This paper describes our extensive simulations to design the optical setup to be employed with G-APD's. We also discuss the reflector configurations, pixel layouts, light concentrators, microlens arrays and spectral efficiencies to optimize light collection. The electronic aspects of our work were presented in a recent companion paper (Pellion et al., Exp. Astron. 27(3):187, 2010).

  3. Construyendo sentido sobre las líneas cartográficas notables del planisferio: astronomía a ras del suelo y cartografía orientada

    OpenAIRE

    Knopoff, Patricia A.; Badagnani, Daniel; Lacambra, Emilio; Llerena Suster, Egly Norka

    2014-01-01

    La enseñanza de las líneas cartográficas notables en la currícula oficial de la educación obligatoria se coloca en situación de riesgo al producir aprendizajes memorísticos que no generan conceptualizaciones significativas. De esta forma, los términos “Ecuador”, “Trópico” o “Polo” son reconocidos fácilmente por la mayor parte de la ciudadanía, pero una indagación más profunda arroja como resultado que son conceptos vacíos de contenido y que no se alcanzan a relacionar con los fenómenos astron...

  4. Numerical Simulations of Solar Spicule Jets at a Magnetic Null-Point

    Science.gov (United States)

    Smirnova, V.; Konkol, P. M.; Solov'ev, A. A.; Murawski, K.

    2016-09-01

    Two-dimensional numerical simulations of jet-like structures in the solar atmosphere are performed. These structures result from a pressure pulse that is launched at the null point of a potential magnetic arcade. The plasma jet exhibits a double structure with two components: (a) dense, cool, and short vertical stream and (b) a less dense, hot and tall part of the jet. The upper part of the hot and tall jet may represent a direct response of the system to the pressure pulse launched at the null point, and the second, slower cool and dense part of the jet is formed later through the stretching up of the stream as a result of plasma evacuation from the top of the magnetic arcade. Numerical results show that jet-like structures mimic some properties of both type I and type II spicules, according to the classification provided by De Pontieu et al. (Publ. Astron. Soc. Japan 59, S655, 2007).

  5. RADIOASTRON OBSERVATIONS OF THE QUASAR 3C273: A CHALLENGE TO THE BRIGHTNESS TEMPERATURE LIMIT

    Energy Technology Data Exchange (ETDEWEB)

    Kovalev, Y. Y.; Kardashev, N. S.; Voitsik, P. A.; Kovalev, Yu. A.; Lisakov, M. M.; Sokolovsky, K. V. [Astro Space Center of Lebedev Physical Institute, Profsoyuznaya 84/32, 117997 Moscow (Russian Federation); Kellermann, K. I. [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903-2475 (United States); Lobanov, A. P.; Zensus, J. A.; Anderson, J. M.; Bach, U.; Kraus, A. [Max-Planck-Institute for Radio Astronomy, Auf dem Hügel 69, D-53121 (Germany); Johnson, M. D. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Gurvits, L. I. [Joint Institute for VLBI ERIC, P.O. Box 2, 7990 AA Dwingeloo (Netherlands); Jauncey, D. L. [CSIRO Astronomy and Space Sciences, Epping, NSW 1710 (Australia); Ghigo, F. [National Radio Astronomy Observatory, Rt. 28/92, Green Bank, WV 24944-0002 (United States); Ghosh, T.; Salter, C. J. [Arecibo Observatory, NAIC, HC3 Box 53995, Arecibo, Puerto Rico, PR 00612 (United States); Petrov, L. Yu. [Astrogeo Center, 7312 Sportsman Drive, Falls Church, VA 22043 (United States); Romney, J. D. [National Radio Astronomy Observatory, P.O. Box O, 1003 Lopezville Road, Socorro, NM 87801-0387 (United States)

    2016-03-20

    Inverse Compton cooling limits the brightness temperature of the radiating plasma to a maximum of 10{sup 11.5} K. Relativistic boosting can increase its observed value, but apparent brightness temperatures much in excess of 10{sup 13} K are inaccessible using ground-based very long baseline interferometry (VLBI) at any wavelength. We present observations of the quasar 3C 273, made with the space VLBI mission RadioAstron on baselines up to 171,000 km, which directly reveal the presence of angular structure as small as 26 μas (2.7 light months) and brightness temperature in excess of 10{sup 13} K. These measurements challenge our understanding of the non-thermal continuum emission in the vicinity of supermassive black holes and require a much higher Doppler factor than what is determined from jet apparent kinematics.

  6. Software tools and preliminary design of a control system for the 40m OAN radiotelescope

    Science.gov (United States)

    de Vicente, P.; Bolaño, R.

    2004-07-01

    The Observatorio Astronómico Nacional (OAN) is building a 40m radiotelescope in its facilities in Yebes (Spain) which will be delivered by April 2004. The servosystem will be controlled by an ACU (Antenna Control Unit), a real time computer running VxWorks which will be commanded from a remote computer (RCC) or from a local computer (LCC) which will act as console. We present the tools we have chosen to develop and use the control system for the RCC and the criteria followed for the choices we made. We also present a preliminary design of the control system on which we are currently working. The RCC will run a server which communicates with the ACU using sockets and with the clients, receivers and backends using OmniOrb, a free implementation of CORBA. Clients running Python will allow the users to control the antenna from any host connected to a LAN or a secure Internet connection.

  7. Atlas of monochromatic images of planetary nebulae

    Science.gov (United States)

    Weidmann, W. A.; Schmidt, E. O.; Vena Valdarenas, R. R.; Ahumada, J. A.; Volpe, M. G.; Mudrik, A.

    2016-08-01

    We present an atlas of more than one hundred original images of planetary nebulae (PNe). These images were taken in a narrow-band filter centred on the nebular emission of the [N ii] during several observing campaigns using two moderate-aperture telescopes, at the Complejo Astronómico El Leoncito (CASLEO), and the Estación Astrofísica de Bosque Alegre (EABA), both in Argentina. The data provided by this atlas represent one of the most extensive image surveys of PNe in [N ii]. We compare the new images with those available in the literature, and briefly describe all cases in which our [N ii] images reveal new and interesting structures. The reduced images as FITS files are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/592/A103

  8. Spectrophotometric intracutaneous analysis for differential diagnosis of pigmented skin lesions

    Directory of Open Access Journals (Sweden)

    Е. V. Filonenko

    2013-01-01

    Full Text Available The non-invasive diagnosis of pigmented skin lesions by spectrophotometric intracutaneous analysis (SIA-scopy using device for dermatoscopy (SIAscope V by Astron Clinica, Ltd was approved in P.A.Herzen Moscow Cancer Research Institute. The method is based on analysis of light interaction with wavelength of 440–960 nm anf human skin, which is recorded by change of image on scan. The comparative analysis of SIA-scopy and histological data in 327 pigmented skin lesions in 147 patients showed, that SIA had high diagnostic efficiency for cutaneous melanoma: the sensitivity was 96%, specifity – 94%, diagnostic accuracy – 94%. For study of malignant potential of pigmented lesions by SIA-scopy the most informative capacity was obtained for assessment of melanin in papillary dermis, status of blood vessels and collagen fibres (SIA-scans 3, 4, 5.

  9. Astroclimatic Characterization of Vallecitos: A candidate site for the Cherenkov Telescope Array at San Pedro Martir

    CERN Document Server

    Tovmassian, Gagik; Ochoa, Jose Luis; Ernenwein, Jean-Pierre; Mandat, Dusan; Pech, Miroslav; Frayn, Ilse Plauchu; Colorado, Enrique; Murillo, Jose Manuel; Cesena, Urania; Garcia, Benjamin; Lee, William H; Bulik, Tomasz; Garczarczyk, Markus; Fruck, Christian; Costantini, Heide; Cieslar, Marek; Aune, Taylor; Vincent, Stephane; Carr, John; Serre, Natalia; Janecek, Petr; Haefner, Dennis

    2016-01-01

    We conducted an 18 month long study of the weather conditions of the Vallecitos, a proposed site in Mexico to harbor the northern array of the Cherenkov Telescope Array (CTA). It is located in Sierra de San Pedro Martir (SPM) a few kilometers away from Observatorio Astron\\'omico Nacional. The study is based on data collected by the ATMOSCOPE, a multi-sensor instrument measuring the weather and sky conditions, which was commissioned and built by the CTA Consortium. Additionally, we compare the weather conditions of the optical observatory at SPM to the Vallecitos regarding temperature, humidity, and wind distributions. It appears that the excellent conditions at the optical observatory benefit from the presence of microclimate established in the Vallecitos.

  10. On the Use of Roche Equipotentials in Analysing the Problems of Binary and Rotating Stars

    Indian Academy of Sciences (India)

    A. Pathania; A. K. Lal; C. Mohan

    2013-03-01

    Kopal (Adv. Astron. Astrophys., 9, 1, 1972) introduced the concept of Roche equipotentials to analyse the effects of rotational and tidal distortions in case of stars in binary systems. In this approach a mathematical expression for the potential of a star in a binary system is obtained by approximating its inner structure with Roche model. This expression for the potential has been used in subsequent analysis by various authors to analyse the problems of structures and oscillations of synchronous and nonsynchronus binary stars as well as single rotating stars. Occasionally, doubts have been expressed regarding the validity of the use of this approach for analysing nonsynchronous binaries and rotationally and tidally distorted single stars. In this paper we have tried to clarify these doubts.

  11. Alfabetización en Astronomía de docentes de Educación Primaria y de Educación Secundaria en La Plata

    Science.gov (United States)

    De Biasi, M. S.; Orellana, R. B.

    2014-10-01

    La educación de este siglo tiene como uno de sus retos alcanzar la alfabetización cientfica de todos los ciudadanos para que comprendan y tomen decisiones sobre el mundo natural y sus cambios originados por la actividad humana utilizando el conocimiento científico. En esta misión los docentes de los niveles obligatorios de enseñanza juegan un papel clave por su rol de agentes multiplicadores del conocimiento. Se requiere, entonces de una adecuada alfabetización en ciencias de los docentes o, como mínimo, que dominen los temas científicos a enseñar. En el campo de la Astronomía, numerosas investigaciones han señalado que maestros de primaria y estudiantes de profesorados poseen una escasa formación en estos temas (Camino 1995 y 1999, Gangui 2010), que frecuentemente presentan a los alumnos concepciones alternativas o no científicas de los fenómenos astronómicos cotidianos (Kriner 2004, Vega Navarro 2007, Gangui et al 2010); a lo que se suma la presentación confusa o errónea de algunos temas astronómicos en los textos escolares (Kriner 2004). Desde 2011, la Facultad de Ciencias Astronómicas y Geofísicas, UNLP, ofrece un curso de capacitación destinado a fortalecer y actualizar los contenidos académicos y didácticos de los docentes del distrito La Plata utilizando diversas estrategias didácticas. Los contenidos comprenden los temas astronómicos de los diseños curriculares vigentes. La evaluación diagnóstica de los conocimientos previos de los docentes cursantes sobre los contenidos de mayor presencia en los diseños curriculares mostró resultados similares a las investigaciones arriba mencionadas. Referente a los movimientos de la Tierra, en promedio, el 54% poseía conceptos erróneos y el 16% no los sabía; con referencia a la Luna el 56% poseía conceptos erróneos y un 4% no los sabía. Los resultados del curso mostraron que el 95% de los docentes revirtió sus conceptos previos erróneos, que adquirió criterios para la búsqueda de

  12. Learning Astronomy by Playing in a Park. (Spanish Title: Aprender AstronoMía Jugando en Una Plaza.) Aprender Astronomia Brincando em Uma Praça

    Science.gov (United States)

    Camino, Néstor

    2012-12-01

    Some public-square games are presented in this paper, considered as didactic modules to help children imagine astronomical processes, based on the concept that learning in Astronomy should be developed to strengthen the relationship of our body with three-dimensional space and time, much in the same way we experience when observing the actual sky, holding a permanent "dialogue" between the actual world and what is to be learned. The games presented (merry-go-rounds and slides) were designed to work on the astronomical concepts related to the translation of the Earth around the Sun, the phases of the Moon and gravity, and on what is perceived by an observer about those phenomena. The description of each game, their physical and astronomical foundations, and a critical comment about their didactical importance are the key parts of the paper. Finally, a recommendation is given about the role teachers should play to be essential partners in the process of learning Astronomy by means of the interaction with these games. Se presentan en este trabajo algunos juegos de plaza, considerados como módulos didácticos para imaginar procesos astronómicos, a partir de la concepción de que el aprendizaje en Astronomía debe desarrollarse fortaleciendo la relación del propio cuerpo con el espacio tridimensional y con el tiempo, tal como se vive al observar el cielo, construyendo un "diálogo" entre el mundo real y los aprendizajes a construir. Los juegos presentados (calesitas y toboganes) fueron diseñados para trabajar sobre la traslación de la Tierra en torno al Sol, las fases de la Luna y la gravedad, y sobre lo que un observador percibe de los mismos. Se da la descripción de cada juego, se discuten sus fundamentos físicos y astronómicos, y se desarrolla una crítica didáctica de los mismos. Finalmente, se comenta el rol que deberían tener los docentes en el acompañamiento a los aprendices en el proceso de interacción con los juegos presentados. Apresentam-se neste

  13. Comportamiento de la cromósfera solar en la línea H-alpha durante el ciclo 23

    Science.gov (United States)

    Davoli, D.; Aquilano, R.; Missio, H.

    Using the instrumental of the Observatorio Astronómico Municipal de Rosario (OAMR), we analyze the solar chromospheric activity during an approximate period of 11 years. The instrument is a Carl Zeiss refractor telescope of 150 mm aperture and 2250 mm of focal distance with monochromatic filter in the H-alpha line. We take as proxy for the solar activity the area covered by chromospheric plages. Simultaneously, we determine the relative wolf number from observations of the solar photosphere. We describe our technique and the results obtained. We observe 2 maxima of solar activity in the years 2000 and 2001 respectively, and a later decrease of this activity with low average values starting around 2006 that corresponds to the end of cycle 23. FULL TEXT IN SPANISH

  14. Numerical Results for the System Noise Temperature of an Aperture Array Tile and Comparison with Measurements

    CERN Document Server

    Ivashina, M V; Bakker, L; Witvers, R H

    2011-01-01

    The purpose of this report is to document the noise performance of a complex beamforming array antenna system and to characterize the recently developed noise measurement facility called THACO, which was developed at ASTRON. The receiver system includes the array antenna of strongly coupled 144 TSA elements, 144 Low Noise Amplifiers (LNAs) (Tmin =35-40K) and the data recording/storing facilities of the initial test station that allow for off-line digital beamforming. The primary goal of this study is to compare the measured receiver noise temperatures with the simulated values for several practical beamformers, and to predict the associated receiver noise coupling contribution, antenna thermal noise and ground noise pick-up (due to the back radiation).

  15. Physics of collisionless phase mixing

    CERN Document Server

    Tsiklauri, D

    2008-01-01

    A previous study [Tsiklauri et al., 2005, Astron. Astrophys., 435, 1105] of phase mixing of ion cyclotron (IC), Alfvenic, waves in the collisionless regime has established the generation of parallel electric field and hence acceleration of electrons in the regions of transverse density inhomogeneity. However, outstanding issues were left open. Here we bridge the gap in understanding by establishing the following: (i) Using the generalised Ohm's law we find that the parallel electric field is supported mostly by the electron pressure tensor, with a smaller contribution from the electron inertia term. (ii) The generated parallel electric field and the fraction of accelerated electrons are independent of the IC wave frequency remaining at a level of six orders of magnitude larger than the Dreicer value and approximately 20% respectively. The generated parallel electric field and the fraction of accelerated electrons increase with the increase of IC wave amplitude. The generated parallel electric field seems to b...

  16. Existence of traversable wormholes in the spherical stellar systems

    Science.gov (United States)

    Övgün, A.; Halilsoy, M.

    2016-07-01

    Potentiality of the presence of traversable wormholes in the outer/inner regions of the halos of galaxies, situated on the Navarro-Frenk-White (NFW) density profile and Universal Rotation Curve (URC) dark matter models have been investigated recently (Rahaman et al. in Eur. Phys. J. C 74:2750, 2014a; Rahaman et al. in Ann. Phys. 350:561-567, 2014b; Kuhfittig in Eur. Phys. J. C 74:2818, 2014a; Kuhfittig in Found. Phys. 7:111-119, 2014b; Kuhfittig in Int. J. Mod. Phys. D 24(03):1550023, 2015; Rahaman et al. in Astrophys. Space Sci. 361(1):37, 2016a; Rahaman et al. in Astrophys. Space Sci. 361(3):90, 2016b). Since this covers our own galaxy also as a possible home for traversable wormholes it prompts us to further the subject by considering alternative density distributions. From this token herein we make use of the Einasto model (Einasto in Tr. Inst. Astrofiz. Alma-Ata 5:87, 1965; Einasto and Haud in Galaxy Astron. Astrophys. 223:89, 1989; Merritt et al. in Astron. J. 132:6, 2006) to describe the density profiles for the same purpose. Our choice for the latter is based on the fact that theoretical dark matter halos produced in computer simulations are best described by such a profile. For technical reasons we trim the number of parameters in the Einasto profile to a possible minimum. Based on such a model it is shown that traversable wormholes in the outer regions of spiral galaxies are possible while the inner part regions prohibit such formations.

  17. Causal production of the electromagnetic energy flux and role of the negative energies in the Blandford-Znajek process

    Science.gov (United States)

    Toma, Kenji; Takahara, Fumio

    2016-06-01

    The Blandford-Znajek process, the steady electromagnetic energy extraction from a rotating black hole (BH), is widely believed to work for driving relativistic jets in active galactic nuclei, gamma-ray bursts, and Galactic microquasars, although it is still under debate how the Poynting flux is causally produced and how the rotational energy of the BH is reduced. We generically discuss the Kerr BH magnetosphere filled with a collisionless plasma screening the electric field along the magnetic field, extending the arguments of Komissarov [S. S. Komissarov, Mon. Not. R. Astron. Soc., 50, 427 (2004)] and our previous [K. Toma and F. Takahara, Mon. Not. R. Astron. Soc., 442, 2855 (2014)] paper, and propose a new picture for resolving the issues. For the magnetic field lines threading the equatorial plane in the ergosphere, we find that the inflow of particles with negative energy as measured in the coordinate basis is generated near that plane as a feedback from the Poynting flux production, which appears to be a similar process to the mechanical Penrose process. For the field lines threading the event horizon, we first show that the concept of the steady inflow of negative electromagnetic energy is not physically essential, partly because the sign of the electromagnetic energy density depends on the coordinates. Then we build an analytical toy model of a time-dependent process in both the Boyer-Lindquist and Kerr-Schild coordinate systems, in which the force-free plasma injected continuously fills a vacuum, and suggest that the structure of the steady outward Poynting flux is causally constructed by the displacement current and the cross-field current at the ingoing boundary between the plasma and the vacuum. In the steady state, the Poynting flux is maintained without any electromagnetic source.

  18. Coupling the nongravitational forces and modified Newton dynamics for cometary orbits

    Science.gov (United States)

    Maquet, Lucie; Pierret, Frédéric

    2015-04-01

    In recent work [L. Blanchet and J. Novak, Mon. Not. R. Astron. Soc. 412, 2530 (2011); L. Blanchet and J. Novak, Testing MOND in the Solar System (2011); and M. Milgrom, Mon. Not. R. Astron. Soc. 399, 474 (2009)], the authors showed that modified Newton dynamics (MOND) has a non-negligible secular perturbation effect on planets with large semimajor axes (gaseous planets) in the Solar System. Some comets also have a very eccentric orbit with a large semimajor axis (Halley family comets) going far away from the Sun (more than 15 AU) in a low acceleration regime where they would be subject to MOND perturbation. They also approach the Sun very closely (less than 3 AU) and are affected by the sublimation of ices from their nucleus, triggering so-called nongravitational forces. The main goal of this paper is to investigate the effect of MOND perturbation on three comets with various orbital elements (2 P /Encke , 1 P /Halley and 153 P /Ikeya-Zhang ) and then compare it to the nongravitational perturbations. It is motivated by the fact that when fitting an outgassing model for a comet, we have to take into account all of the small perturbing effects to avoid absorbing these effects into the nongravitational parameters. Otherwise, we could derive a completely wrong estimation of the outgassing. For this work, we use six different forms of MOND functions and compute the secular variations of the orbital elements due to MOND and nongravitational perturbations. We show that, for comets with large semimajor axis, the MONDian effects are not negligible compared to the nongravitational perturbations.

  19. San Pedro Mártir mid-infrared photometric system

    Directory of Open Access Journals (Sweden)

    Luis Salas

    2006-01-01

    Full Text Available Con el objetivo de definir el Sistema Fotométrico para el Mediano-Infrarrojo de San Pedro Mártir, se realizaron observaciones de estrellas de calibración bien estudiadas con la cámara del mediano-infrarrojo CID-BIB (2 - 28 m del Observatorio Astronómico Nacional, durante 9 temporadas de observación en 2000 a 2005. Se utilizó un conjunto de 9 filtros, los de la serie de “silicatos" SiN, SiO, SiP, SiQ, SiR, SiS, el filtro de banda ancha N (10.8 m, y los filtros angostos QH2 (17.15 m y Q2 (18.7 m, para determinar los coeficientes de extinción y los puntos cero en magnitud. Las correcciones por extinción atmosférica se llevaron a cabo mediante el uso de aproximantes de Padé, y los coeficientes involucrados se obtuvieron mediante una relacion lineal con el coeficiente de extinción a baja masa de aire. Se presentan y comparan las curvas de transmisión atmosférica de SPM y los coeficientes de extinción con los del sitio astronómico Mauna Kea. Utilizando un conjunto de fuentes IRAS LSR observadas con el CID-BIB se encuentran terminos de color.

  20. "Prospecting Asteroids: Indirect technique to estimate overall density and inner composition"

    Science.gov (United States)

    Such, Pamela

    2016-07-01

    Spectroscopic studies of asteroids make possible to obtain some information on their composition from the surface but say little about the innermost material, porosity and density of the object. In addition, spectroscopic observations are affected by the effects of "space weathering" produced by the bombardment of charged particles for certain materials that change their chemical structure, albedo and other physical properties, partly altering their chances of identification. Data such as the mass, size and density of the asteroids are essential at the time to propose space missions in order to determine the best candidates for space exploration and is of great importance to determine a priori any of them remotely from Earth. From many years ago its determined masses of largest asteroids studying the gravitational effects they have on smaller asteroids when they approach them (see Davis and Bender, 1977; Schubart and Matson, 1979; School et al 1987; Hoffman, 1989b, among others), but estimates of the masses of the smallest objects is limited to the effects that occur in extreme close encounters to other asteroids of similar size. This paper presents the results of a search for approaches of pair of asteroids that approximate distances less than 0.0004 UA (50,000 km) of each other in order to study their masses through the astrometric method and to estimate in a future their densities and internal composition. References Davis, D. R., and D. F. Bender. 1977. Asteroid mass determinations: search for futher encounter opportunities. Bull. Am. Astron. Soc. 9, 502-503. Hoffman, M. 1989b. Asteroid mass determination: Present situation and perspectives. In asteroids II (R. P. Binzel, T. Gehreis, and M. S. Matthews, Eds.), pp 228-239. Univ. Arizona Press, Tucson. School, H. L. D. Schmadel and S. Roser 1987. The mass of the asteroid (10) Hygiea derived from observations of (829) Academia. Astron. Astrophys. 179, 311-316. Schubart, J. And D. L. Matson 1979. Masses and

  1. Calidad de Imagen del Telescopio UNAM212

    Science.gov (United States)

    Cobos, F. J.; Teiada de Vargas, C.

    1987-05-01

    El telescopio UNAM2l2, del Observatorio Astronómico Nacional, situado en la Sierra de San Pedro Mártir (Baja California, México), cumplira en un futuro muy cercano siete años de uso para fines de investigación astronómica. Aunque en este tiempo no se ha efectuado un estudio sistemático acerca de su comportamiento óptico y de los factores que influyen en la calidad de las imágenes, se han realizado pruebas diversas, estudios parciales y reuniones especificas, cuyos resultados no siempre se han difundido ampliamente y generalmente no se han presentado por escrito. Es por ello que hemos creido necesario intentar una recopilación de la información existente para poder con ella establecer un diagnóstjco que, aunque no sea definitivo, sirva de base para futuros trabajos tendientes a optimizar el comportamiento óptico del telescopio. Es evidente que un buen número de las conclusiones que se presentan son resultado del trabajo de muchas personas ó de esfuerzos colectivos. Asimismo, hemos tratado de localizar información bibliográfica que pueda ser de utilidad. Nuestro objetivo primordial ha consistido en centrarnos en la óptica del telescopio y su calidad, pero también se han considerado otros aspectos que puedan afectar las imágenes obtenidas tales como: celda del primario, `seeing' local y externo, flexiones posibles en la estructura mecánica del telescopio, etc.

  2. Properties of the exact analytic solution of the growth factor and its applications

    International Nuclear Information System (INIS)

    There have been the approximate analytic solution [V. Silveira and I. Waga, Phys. Rev. D 50, 4890 (1994).] and several approximate analytic forms [W. J. Percival, Astron. Astrophys. 443, 819 (2005).][S. M. Carroll, W. H. Press, and E. L. Turner, Annu. Rev. Astron. Astrophys. 30, 499 (1992).][S. Basilakos, Astrophys. J. 590, 636 (2003).] of the growth factor Dg for the general dark energy models with the constant values of its equation of state ωde after Heath found the exact integral form of the solution of Dg for the Universe including the cosmological constant or the curvature term. Recently, we obtained the exact analytic solutions of the growth factor for both ωde=-1 or -(1/3)[S. Lee and K.-W. Ng, arXiv:0905.1522.] and the general dark energy models with the constant equation of state ωde[S. Lee and K.-W. Ng, Phys. Lett. B 688, 1 (2010).] independently. We compare the exact analytic solution of Dg with the other well known approximate solutions. We also prove that the analytic solutions for ωde=-1 or -(1/3) in [S. Lee and K.-W. Ng, arXiv:0905.1522.] are the specific solutions of the exact solutions of the growth factor for general ωde models in [S. Lee and K.-W. Ng, Phys. Lett. B 688, 1 (2010).] even though they look quite different. Comparison with the numerical solution obtained from the public code is done. We also investigate the possible extensions of the exact solution of Dg to the time-varying ωde for the comparison with observations.

  3. La Enseñanza/Aprendizaje del Modelo Sol-Tierra Análisis de la Situación Actual y Propuesta de Mejora Para la Formación de los Futuros Profesores de Primaria

    Science.gov (United States)

    Martínez Sebastià, Bernat

    2004-12-01

    This work is an extened summary of the autor's PhD thesis. It deals with the teaching of astronomy (day/night, seasons) in primary school. At first, students teachers' undestanding of astronomical concepts related to Sun-Earth system have been analysed. Taking into account the results of the previous analysis and using a socio-constructivist approach a teaching sequence has been designed. This sequence has been tested with different groups of students teachers showing an improvement in their undestanding of elementary astronomical concepts. El trabajo que presentamos es un resumen extenso de la tesis doctoral del autor. El enfoque utilizado ha sido tratar de ligar la investigación sobre las ideas, razonamientos y obstáculos de los profesores de primaria con la planificación de la enseñanza del modelo Sol-Tierra que permite explicar el ciclo día/noche y las estaciones. En primer lugar, se ha procedido a realizar un análisis crítico de los resultados que se obtienen en el aprendizaje de los contenidos astronómicos en la enseñanza habitual. En segundo lugar se ha diseñado un curriculum potencialmente superador de esta situación desde una orientación que concibe la enseñanza y el aprendizaje como un proceso de construcción de conocimientos en una estructura problematizada. Finalmente, esta secuencia didáctica ha sido experimentada con diferentes grupos de estudiantes de magisterio, mostrando una mejora relevante en la comprensión de los conceptos astronómicos fundamentales.

  4. Establishing the Empirical Relationship Between Non-Science Majoring Undergraduate Learners' Spatial Thinking Skills and Their Conceptual Astronomy Knowledge. (Spanish Title: Estableciendo Una Relación Empírica Entre el Razonamiento Espacial de los Estudiantes de Graduación de Carreras no Científicas y su Conocimento Conceptual de la Astronomía.) Estabelecendo Uma Relação Empírica Entre o RacioCínio Espacial dos Estudantes de Graduação EM Carreiras Não Científicas e Seu Conhecimento Conceitual da Astronomia

    Science.gov (United States)

    Heyer, Inge; Slater, Stephanie J.; Slater, Timothy F.

    2013-12-01

    The astronomy education community has tacitly assumed that learning astronomy is a conceptual domain resting upon spatial thinking skills. As a first step to formally identify an empirical relationship, undergraduate students in a non-major introductory astronomy survey class at a mediumsized, Ph.D. granting, mid-western US university were given pre- and post-astronomy conceptual diagnostics and spatial reasoning diagnostics, Instruments used were the "Test Of Astronomy Standards" and "What Do You Know?" Using only fully matched data for analysis, our sample consisted of 86 undergraduate non-science majors. Students' normalized gains for astronomy surveys were low at .26 and .13 respectively. Students' spatial thinking was measured using an instrument designed specifically for this study. Correlations between the astronomy instruments' pre- to post-course gain scores and the spatial assessment instrument show moderate to strong relationships suggesting the relationship between spatial reasoning and astronomy ability can explain about 25% of the variation in student achievement. La comunidad de educación en astronomía ha supuesto de forma tácita que el aprendizaje de la astronomía consiste en un dominio conceptual fundamentado en el razonamiento espacial. Como un primer paso para identificar formalmente una relación empírica entre estas dos cosas, utilizamos como muestra los estudantes de graduación de carreras no científicas de un curso experimental en una universidad norteamericana del medioeste de porte mediano con programa de Doctorado em curso, en el cual estos estudiantes se sometieron a un diagnóstico de razonamiento espacial y conceptos astronómicos antes e después del mismo. Las herramientas utilizadas fueron el Test Of Astronomy Standards (TOAST) y el cuestionario What do you know? Utilizando solo los datos completamente consistentes para este análisis, nuestra muestra consistió en 86 estudantes de graduación. Las mejoras, depués de

  5. THE POPULARIZATION OF ASTRONOMY IN THE TEACHING OF GEOGRAPHY: an experience in the middle and high school

    Directory of Open Access Journals (Sweden)

    Márcio Balbino Cavalcante

    2012-12-01

    Full Text Available It is a very old man's concern to know the mysteries of the universe. Geography is defined as the study of the relationship between space and society, is, par excellence, discipline and interdisciplinary teaching should focus on various aspects of society and nature. The present study was aimed to popularize astronomy in Geography lessons of elementary and secondary public and private schools of the municipality the of Passa e Fica/RN, with reference to the achievement of the Olympiad of Astronomy and Astronautics - OBA, sponsored by the Institute Physics - UERJ in partnership with the Sociedade Astronômica Brasileira (SAB and the Agência Espacial Brasileira (AEB. The achievement of this Article, the following steps were undertaken: literature search and mapping, field survey;-class ride to Centro de Lançamento de Foguetes da Barreira do Inferno, em Natal/RN; lectures, telescopic observations, workshops for carrying out activities practices such as the sundial, replica rocket, compass; classroom discussion of the data collected, the material made with exposure and mobilization involving the school community and the Government. According to the results, interdisciplinary work between geography and astronomy produced a privileged space for the construction and popularization of scientific knowledge founded on the reality experienced by the student, always with a critical and constructive, which often is ignored in school work. RESUMO: É muito antiga a preocupação do homem em conhecer os mistérios do universo. A Geografia é definida como o estudo das relações entre o espaço e as sociedades, é, por excelência, uma disciplina interdisciplinar e seu ensino deve enfocar diversos aspectos da sociedade e da natureza. O presente trabalho teve objetivo de popularizar a Astronomia nas aulas de Geografia dos ensinos fundamental e médio das escolas públicas e particulares do município de Passa e Fica/RN; tendo como referência a realiza

  6. Link between interplanetary & cometary dust: Polarimetric observations and space studies with Rosetta & Eye-Sat

    Science.gov (United States)

    Levasseur-Regourd, Anny-Chantal; Gaboriaud, Alain; Buil, Christian; Ressouche, Antoine; Lasue, J.; Palun, Adrien; Apper, Fabien; Elmaleh, Marc

    in 2016 [7]. Its main purpose is to study the zodiacal light intensity and polarization from a Sun-synchronous orbit, for the first time at the high spatial resolution of 1° over a wide portion of the sky and at four different wavelengths (in the visible and near-IR domains). The instrumental choices and new on-board technologies will be summarized, together with the results that may be expected on local properties of the interplanetary dust particles and thus on their similarities and differences with cometary dust particles. Support from CNES is warmly acknowledged. [1] Leinert, C., Bowyer, S., Haikala, L.K., et al. The 1997 reference of diffuse night sky brightness, Astron. Astrophys. Supp., 127, 1-99, 1998. [2] Levasseur-Regourd, A.C., Mann, I., Dumont, R., et al. Optical and thermal properties of interplanetary dust. In Interplanetary dust (Grün, E. et al. Eds), 57-94, Springer-Verlag, Berlin, 2001. [3] Lasue, J., Levasseur-Regourd, A.C., Fray, N., et al. Inferring the interplanetary dust properties from remote observations and simulations, Astron. Astrophys., 473, 641-649, 2007. [4] Nesvorny, D., Jenniskens, P., Levison, H.F., et al. Cometary origin of the zodiacal cloud and carbonaceous micrometeorites: implications for hot debris disks. Astrophys. J. 713, 816-836, 2010. [5] Levasseur-Regourd, A.C., Mukai, T., Lasue, J., et al. Physical properties of cometary and interplanetary dust, Planet. Space Sci., 55, 1010-1020, 2007. [6] Hadamcik, E., Sen, A.K., Levasseur-Regourd, A.C., et al., Astron. Astrophys., 517, A86, 2010. [7] CNES internal report. Eye-Sat end of phase A internal review, EYESAT-PR-0-022-CNES, 2013.

  7. Corrections stemming from the non-osculating character of the Andoyer variables used in the description of rotation of the elastic Earth

    Science.gov (United States)

    Escapa, Alberto

    2011-06-01

    We explore the evolution of the angular velocity of an elastic Earth model, within the Hamiltonian formalism. The evolution of the rotation state of the Earth is caused by the tidal deformation exerted by the Moon and the Sun. It can be demonstrated that the tidal perturbation to spin depends not only upon the instantaneous orientation of the Earth, but also upon its instantaneous angular velocity. Parameterizing the orientation of the Earth figure axis with the three Euler angles, and introducing the canonical momenta conjugated to these, one can then show that the tidal perturbation depends both upon the angles and the momenta. This circumstance complicates the integration of the rotational motion. Specifically, when the integration is carried out in terms of the canonical Andoyer variables (which are the rotational analogues to the orbital Delaunay variables), one should keep in mind the following subtlety: under the said kind of perturbations, the functional dependence of the angular velocity upon the Andoyer elements differs from the unperturbed dependence (Efroimsky in Proceedings of Journées 2004: Systèmes de référence spatio-temporels. l'Observatoire de Paris, pp 74-81, 2005; Efroimsky and Escapa in Celest. Mech. Dyn. Astron. 98:251-283, 2007). This happens because, under angular velocity dependent perturbations, the requirement for the Andoyer elements to be canonical comes into a contradiction with the requirement for these elements to be osculating, a situation that parallels a similar antinomy in orbital dynamics. Under the said perturbations, the expression for the angular velocity acquires an additional contribution, the so called convective term. Hence, the time variation induced on the angular velocity by the tidal deformation contains two parts. The first one comes from the direct terms, caused by the action of the elastic perturbation on the torque-free expressions of the angular velocity. The second one arises from the convective terms. We

  8. Origin and Evolution of the Cometary Reservoirs

    Science.gov (United States)

    Dones, Luke; Brasser, Ramon; Kaib, Nathan; Rickman, Hans

    2015-12-01

    underwent a dynamical instability that led to a flood of comets and asteroids throughout the Solar System (Gomes et al. in Nature 435:466-469, 2005b). In this scenario, it is somewhat a matter of luck whether an icy planetesimal ends up in the Kuiper Belt or Oort Cloud (Brasser and Morbidelli in Icarus 225:40-49, 2013), as a Trojan asteroid (Morbidelli et al. in Nature 435:462-465, 2005; Nesvorný and Vokrouhlický in Astron. J. 137:5003-5011, 2009; Nesvorný et al. in Astrophys. J. 768:45, 2013), or as a distant "irregular" satellite of a giant planet (Nesvorný et al. in Astron. J. 133:1962-1976, 2007). Comets could even have been captured into the asteroid belt (Levison et al. in Nature 460:364-366, 2009). The remarkable finding of two "inner Oort Cloud" bodies, Sedna and 2012 VP_{113}, with perihelion distances of 76 and 81 AU, respectively (Brown et al. in Astrophys. J. 617:645-649, 2004; Trujillo and Sheppard in Nature 507:471-474, 2014), along with the discovery of other likely inner Oort Cloud bodies (Chen et al. in Astrophys. J. Lett. 775:8, 2013; Brasser and Schwamb in Mon. Not. R. Astron. Soc. 446:3788-3796, 2015), suggests that the Sun formed in a denser environment, i.e., in a star cluster (Brasser et al. in Icarus 184:59-82, 2006, 191:413-433, 2007, 217:1-19, 2012b; Kaib and Quinn in Icarus 197:221-238, 2008). The Sun may have orbited closer or further from the center of the Galaxy than it does now, with implications for the structure of the Oort Cloud (Kaib et al. in Icarus 215:491-507, 2011).

  9. Impact and cratering rates onto Pluto

    Science.gov (United States)

    Greenstreet, Sarah; Gladman, Brett; McKinnon, William B.

    2015-09-01

    The New Horizons spacecraft fly-through of the Pluto system in July 2015 will provide humanity's first data for the crater populations on Pluto and its binary companion, Charon. In principle, these surfaces could be dated in an absolute sense, using the observed surface crater density (# craters/km2 larger than some threshold crater diameter D). Success, however, requires an understanding of both the cratering physics and absolute impactor flux. The Canada-France Ecliptic Plane Survey (CFEPS) L7 synthetic model of classical and resonant Kuiper belt populations (Petit, J.M. et al. [2011]. Astron. J. 142, 131-155; Gladman, B. et al. [2012]. Astron. J. 144, 23-47) and the scattering object model of Kaib et al. (Kaib, N., Roškar, R., Quinn, T. [2011]. Icarus 215, 491-507) calibrated by Shankman et al. (Shankman, C. et al. [2013]. Astrophys. J. 764, L2-L5) provide such impact fluxes and thus current primary cratering rates for each dynamical sub-population. We find that four sub-populations (the q 100km) connects to smaller projectiles, we compute cratering rates using five model impactor size distributions: a single power-law, a power-law with a knee, a power-law with a divot, as well as the "wavy" size distributions described in Minton et al. (Minton, D.A. et al. [2012]. Asteroids Comets Meteors Conf. 1667, 6348) and Schlichting et al. (Schlichting, H.E., Fuentes, C.I., Trilling, D.E. [2013]. Astron. J. 146, 36-42). We find that there is only a small chance that Pluto has been hit in the past 4 Gyr by even one impactor with a diameter larger than the known break in the projectile size distribution (d ≈ 100km) which would create a basin on Pluto (D ⩾ 400km in diameter). We show that due to present uncertainties in the impactor size distribution between d = 1-100km , computing absolute ages for the surface of Pluto is entirely dependent on the extrapolation to small sizes and thus fraught with uncertainty. We show, however, what the ages would be for several cases

  10. Analysis of Hubble Space Telescope Observations of an Outburst of Comet 29P/Schwassmann-Wachmann 1

    Science.gov (United States)

    Schambeau, Charles Alfred; Fernandez, Yanga R.; Samarasinha, Nalin H.; Kundu, Arunav

    2016-10-01

    We present results of a continuing analysis on the spin state of the enigmatic Comet 29P/Schwassmann-Wachmann 1 (SW1). Previous works have reported possible constraints on the spin state including a non-principal axis state [1] or a rotation period of tens of days [2]. This diversity of published answers highlights the complexity of determining the spin state of an active comet nucleus. Previous work by our group using 3D Monte Carlo coma modeling of ground-based outburst observations from 2008 [3] has placed constraints on the spin period for a set of assumed spin-pole orientations. Due to the nature of the 2008 outburst morphology no constraints on the spin-pole orientation could be found.We present here an analysis of Hubble Space Telescope WFPC2 observations of SW1 shortly after a 1996 outburst [4] with which we have further constrained the spin state. The 0.046-arcsec/pixel scale (176 km/pixel at SW1) of the PC detector gives an order-of-magnitude improvement in spatial resolution over our ground-based observations. Two sets of observations from UT 1996 Mar. 11.3 and 12.1 show the ejected dust forming an asymmetric outflow contained on the sunward side of the coma. A projected outflow velocity of 0.15 ± 0.02 km/s was measured, similar to our measured value from the 2008 observations. Enhancements of the images were performed [5] to bring out subtle variations in coma brightness (i.e., jets) and to allow us to search for signatures of the nucleus' rotation during the outburst. Three curved features are seen in both sets of observations and were modeled using the 3D Monte Carlo coma model [6]. We find a spin period on the order of several days, in agreement with our earlier 2008 analysis.[1] Meech, K. J., et al.: 1993, Astron. J., 106, 1222. [2] Miles, R., et al.: 2016, Icarus, 272, 327. [3] Schambeau, C. A., et al.: 2016, Icarus, submitted. [4] Feldman, P. D., et al.: 1996, AAS/DPS Meeting Abstracts, 28, 1084. [5] Samarasinha, N. and Larson, S.: 2014, Icarus

  11. USING RE-ANALYSIS MODEL DATA TO ANALYSE CLIMATE TRENDS RELATED TO THE ASTROCLIMATOLOGY OF PARANAL AND LA SILLA

    Directory of Open Access Journals (Sweden)

    E. Graham

    2011-01-01

    Full Text Available Este trabajo consiste en un resumen de los resultados de dos ejercicios de investigación separados. En la primera parte, se examinó la correlación entre magnitudes estadísticas de tiempos de observación astronómica nocturna (seeing y fracción fotométrica nocturna para los observatorios Paranal y la Silla de ESO y 35 variables de reanálisis de ERA-40 y NCEP-NCAR (disponibles con el software FriOWL, usando la información de los reanálisis desde la coordenadas más cercana a los observatorios. Los resultados confirman que los datos de fracción fotométrica nocturna en ambos observatorios están mejor descritos que los datos de seeing. La relacián más fuerte se encontrá en La Silla, debido a su localización baroclínica más hacia el sur. Los datos de emisión de radiacián de onda larga (OLR se desempeñan tan bien o mejor que los datos equivalentes de cubierta nubosa en los reanálisis ERA-40. En la segunda parte del estudio, la herramienta FriOWL se usó en un análisis de la climatología del Norte de Chile para determinar las causas del deterioro en las condiciones astronómicas de seeing en Paranal desde 1998. Los resultados muestran que ha ocurrido un gran incremento en la altura geopotencial de 1000 hPa al Sureste de Paranal en el período 1998-2007, cuando se comparó con los nueve años anteriores. Este incremento, sin embargo, no se observa en los niveles de 700, 500 y 200 hPa. En el mismo período también ocurrió un corrimiento hacia el sur en el eje de altura geopotencial cercana a superficie desde 21°S a 25-27°S. Además, parece que existe un vínculo entre los cambios de fase de la oscilación interdecadal del Pacífico y anomalías de circulación atmosféricas sobre la región del Pacífico.

  12. Valine radiolysis by MeV ions

    Science.gov (United States)

    Da Silveira, Enio

    2016-07-01

    . Ehrenfreund and S. B. Charnley, Annu. Rev. Astron. Astrophys. 2000. 38:427. [2] C. Mejía et al., Icarus 250 (2015) 222. [3] D. P. P. Andrade et al., Mon. Not. R. Astron. Soc. 430 (2013) 787. [4] P. A. Gerakines and R. L. Hudson, Icarus 252 (2015) 466. Acknowledgments. The agencies CNPq (INEspaço) and FAPERJ are acknowledged for partial support to this work.

  13. Proving the Orbits of the Galilean Moons Through Astrophotography. (Spanish Title: Comprobando Las Órbitas de Las Lunas Galileanas a Través de la Astrofotografía.) Evidenciando as Órbitas das Luas Galileanas Atravéd da Astrofotografia

    Science.gov (United States)

    Iachel, Gustavo

    2009-12-01

    An activity related to the observation of the Galilean moons and to amateur astrophotography is presented in this work. Through the reading of excerpts of the book Sidereus Nuncius (Sidereal Messenger), by Galileo, it is possible to trace a methodology to observe the planet and its natural satellites and, with the aid of the astrophotography, to analyze the field recordings. Moreover, it is possible to compare the images obtained after plotting the relative positions of these moons to prove their orbits. This activity can be conducted by teachers, students and amateur astronomers, in order to develop their capabilities of observation of astronomical phenomena. Se presenta en este trabajo una actividad relacionada a la observación de las lunas Galileanas y a la astrofotografía amateur. A través de la lectura de tramos de la obra Sidereus Nuncius (El Mensajero Sideral) de Galileo, es posible trazar una metodología para la observación del planeta y de sus satélites naturales y, con el auxilio de la astrofotografía, analizar las anotaciones de campo. Además, es posible comparar las imágenes obtenidas con el gráfico de las posiciones relativas de estas lunas para comprobar sus órbitas. Esa actividad puede ser realizada por maestros, estudiantes y astrónomos amateurs, de forma a desarrollar sus capacidades de observación de los fenómenos astronómicos. Uma atividade relacionada à observação das luas Galileanas e à astrofotografia amadora é apresentada neste trabalho. Através da leitura de trechos da obra Sidereus Nuncius (Mensageiro Sideral), de Galileu, é possível traçar uma metodologia para a observação do planeta e de seus satélites naturais e, com o auxílio da astrofotografia, analisar as anotações de campo. Além disso, é possível comparar as imagens obtidas com o gráfico das posições relativas destas luas para evidenciar suas órbitas. Essa atividade pode ser realizada por professores, estudantes e astrônomos amadores, de forma a

  14. Taxonomía de asteroides y cometas basada en los espectros de Lyapunov

    Science.gov (United States)

    Tancredi, G.; Motta, V.; Froeschlé, C.

    Estudiaremos dos familias de objetos que sufren encuentros cercanos con planetas, a saber: la familia de cometas de Júpiter (JF) y los asteroides cercanos a la Tierra (NEAs). El movimiento de estos objetos es caótico en una escala de tiempo corta. Más aún, debido a los cambios erráticos en los elementos orbitales, la comparación de los valores actuales da poca información acerca de la posible vinculación dinámica entre los objetos de una misma familia. Calculamos una estimación finita de los Exponentes Característicos de Lyapunov (LCE), los llamamos Indicadores Característicos de Lyapunov (LCI) para ambas familias y analizamos las características del espacio de fase donde tiene lugar el movimiento de estos objetos. Integrando en un período suficientemente largo (e.g. 20000 años), encontramos que el LCI alcanza un valor cuasi-constante. La mayoría de los miembros de ambas familias muestran una concentración de los tiempos de Lyapunov (inverso del LCI) de alrededor de 50-100 años (Tancredi, 1995, Astron & Astrop., 299, 288). La concentración de los tiempos de Lyapunov es mayor para la familia de Júpiter que para los NEAs. Entre estos últimos, la menor dispersión se da para aquellos que cruzan la órbita de la Tierra. Se demostró que el espectro de los `indicadores locales' (Froeschlé et. al., 1990, Cel. Mec. 56, 307) o ``números de estiramiento'' (Voglis and Contopoulos, 1994, J. Phys. A 26, 4899) (relacionados con el LCI) son invariantes y nos dan una información más completa sobre el comportamiento caótico. Mediante la comparación de espectros discutimos la similitud entre los objetos de una misma familia y analizamos las diferentes posibles rutas al caos. Los espectros se clasifican mediante la comparación de los momentos de las distribuciones de los `números de estiramiento'. Aplicamos un método de agrupamiento jerárquico (Zappala et. al., 1990, Astron. J. 100, 2030) para identificar ``familias'' de espectros (grupos de espectros

  15. The Future of Astrometric Education

    Directory of Open Access Journals (Sweden)

    William van Altena

    2006-01-01

    Full Text Available La Astrometría está preparada para entrar en una era de crecimiento y relevancia sin paralelo debido a la esperada abundancia de datos procedentes de las misiones espaciales SIM y GAIA. Se diseñan modernos telescopios terrestres, como el LSST, que brindaran datos menos precisos, pero de una mayor cantidad de estrellas. El potencial para los estudios de estructura, cinemática y dinámica de nuestra Galaxia, así como de la naturaleza física de las estrellas y de las escalas cosmológicas, no tiene igual en la historia de la astronomía. Es irónico, por lo tanto, que a escala global, se puede obtener una educación completa en astrometría sólo en San Petersburgo y en Paris, mientras que en breve, no se dictaría curso alguno de astrometría en los EEUU. ¿Quien aseguraría el control de calidad astrométrico de JWT, SIM, GAIA, LST, por no hablar de los grandes telescopios basados en tierra tales como, VLT, Gemini, Keck, NOAO, Magellan, LBT, etc.? Proponemos una renovación de la educación universitaria en astrometría con el fin de preparar científicos calificados que permitan maximizar los resultados de las actuales inversiones multimillonarias en instrumentación astronómica. Por un lado, las agencias de financiamiento están proporcionando fondos especiales para estos propósitos, y a su vez, las universidades y los observatorios deben reconocer su responsabilidad de contratar astrometrías altamente calificados aún de entrenar estudiantes y supervisar el instrumental astronómico planificado y existente, de tal manera que se obtengan y analicen datos de gran calidad. Una solución provisional a este problema es proponer la realización de series de escuelas internacionales de verano en Astrometría. El Centro Científico Michelson del proyecto SIM coordinarla una escuela de astrometría en 2005, aún de iniciar este proceso. Se sugiere el equivalente a un programa educativo de un semestre en técnicas astrometrías en carreras

  16. The Teaching of Astronomy in Uruguay. (Spanish Title: La Enseñanza de la Astronomía en Uruguay.) O Ensino da Astronomia no Uruguai

    Science.gov (United States)

    Pintos Ganón, Reina; Fernández, Julio Angel

    2008-07-01

    We present in this work the development of astronomy in Uruguay since the colony times up to the present, stressing in particular those aspects related to the formal as well as informal teaching of astronomy. The first antecedents of astronomical studies in our country go back to the beginnings of the XVIIIth century related to the scientific expeditions from Europe coming to our shores. The teaching of astronomy was generalized at the high school level as soon as the end of the XIXth century, while itsintroduction at the university level happened much later, around the middle of the last century. We analyze the current situation of this subject, its problems, and some measures to strengthen its development. Se presenta en este trabajo el desarrollo de la astronomía en el Uruguay desde la época colonial hasta el presente, destacando en particular los aspectos vinculados a su enseñanza tanto formal como informal. Los primeros antecedentes de estudios astronómicos datan de la época colonial relacionados con las expediciones científicas del Viejo Mundo que llegaban a nuestras costas. La enseñanza de la Astronomía se generalizó en el ámbito de los estudios secundarios ya a fines del siglo XIX, mientras que en la Universidad su arribo fue mucho más tardío, a mediados del siglo pasado. Se analiza la situación actual de esta disciplina, sus problemas, y algunas medidas para fortalecer su desarrollo. Apresentamos, neste trabalho, o desenvolvimento da Astronomia no Uruguai desde a época colonial até o presente, destacando em particular os aspectos vinculados ao seu ensino tanto formal quanto informal. Os primeiros antecedentes de estudos astronômicos em nosso país datam da época colonial relacionados com as expedições científicas do Velho Mundo que chegavam às nossas costas. O ensino da Astronomia se generalizou no âmbito dos estudos secundários já no final do século XIX, enquanto que sua introdução na universidade foi muito mais tardia, em

  17. Ensino de astronomia e óptica: é possível fazê-lo de forma contextualizada no nível médio?

    Science.gov (United States)

    Sobrinho, A. A.; Jafelice, L. C.

    2003-08-01

    Discutimos nossa participação em um curso de treinamento para professores de diversas disciplinas do ensino médio. Nossa preocupação básica foi desenvolver instrumentos educacionais adequados para levar à sala de aula, nesse nível de ensino, de forma contextualizada, questionamentos freqüentes dos alunos sobre astronomia e sua relação com tecnologia e sociedade. Encaminhamos questões como: a evolução da astronomia, suas relações com outros ramos do conhecimento humano e conseqüentes aplicações; avanços na tecnologia dos instrumentos ópticos versus a importância da observação do céu a olho nu; a relação entre olho humano, luneta e telescópio; e desenvolvimento da tecnologia espacial e sua influência em nosso cotidiano. Objetivamos com isto fazer um resgate histórico e pedagógico das aplicações e observações do céu no cenário escolar, destacando a relação entre eventos astronômicos, olho humano, instrumentos mediadores e suas contextualizações históricas e sociais. Produtos desta abordagem foram o desenvolvimento e a adaptação de práticas e materiais instrucionais diversos (e.g., "espelhos" de isopor e "raios luminosos" de bolinhas de gude; montagens envolvendo velas, lasers, lentes e espelhos; desmonte e análise de peças de um telescópio; etc.). Além disto, como outro resultado deste trabalho, elaboramos textos sobre história da astronomia e da óptica para atividades em classe. Com estas ações visamos facilitar a concretização de conceitos físicos envolvidos, exemplificar um ensino contextualizado e interdisciplinar motivado por temas astronômicos e favorecer que práticas e discussões feitas com os treinandos possam ser transpostas para a sala de aula. A reação dos professores às práticas propostas foi bastante positiva. Todos esses aspectos são discutidos em detalhe neste trabalho. (PPGECNM/UFRN; PRONEX/FINEP; NUPA/USP; Temáticos/FAPESP)

  18. The many facets of extragalactic radio surveys: towards new scientific challenges

    Science.gov (United States)

    2015-10-01

    Radio continuum surveys are a powerful tool to detect large number of objects over a wide range of redshifts and obtain information on the intensity, polarization and distribution properties of radio sources across the sky. They are essential to answer to fundamental questions of modern astrophysics. Radio astronomy is in the midst of a transformation. Developments in high-speed digital signal processing and broad-band optical fibre links between antennas have enabled significant upgrades of the existing radio facilities (e-MERLIN, JVLA, ATCA-CABB, eEVN, APERTIF), and are leading to next-generation radio telescopes (LOFAR, MWA, ASKAP, MeerKAT). All these efforts will ultimately lead to the realization of the Square Kilometre Array (SKA), which, owing to advances in sensitivity, field-of-view, frequency range and spectral resolution, will yield transformational science in many astrophysical research fields. The purpose of this meeting is to explore new scientific perspectives offered by modern radio surveys, focusing on synergies allowed by multi-frequency, multi-resolution observations. We will bring together researchers working on wide aspects of the physics and evolution of extra-galactic radio sources, from star-forming galaxies to AGNs and clusters of galaxies, including their role as cosmological probes. The organization of this conference has been inspired by the recent celebration of the 50th anniversary of the Northern Cross Radio Telescope in Medicina (BO), whose pioneering B2 and B3 surveys provided a significant contribution to radio astronomical studies for many decades afterwards. The conference was organized by the Istituto di Radioastronomia (INAF), and was held at the CNR Research Area in Bologna, on 20-23 October 2015. This Conference has received support from the following bodies and funding agencies: National Institute for Astrophysics (INAF), ASTRON, RadioNet3 (through the European Union’s Seventh Framework Programme for research

  19. Astronomy Teaching and Teachers Continuing Education: the Interdisciplinarity during a Total Lunar Eclipse. (Spanish Title: Enseñanza de la Astronomía y la Formación Continua de Profesores: la Interdisciplinariedad Durante un Eclipse Total de Luna.) Educação EM Astronomia E Formação Continuada de Professores: a Interdisciplinaridade Durante um Eclipse Lunar TOTAL

    Science.gov (United States)

    Langhi, Rodolfo

    2009-07-01

    This paper describes how 67 teachers from 23 cities, could awaken, in students, the scientific interest, using a natural astronomical phenomenon: a total lunar eclipse. Before and after of eclipse, meetings for continuing education were characterized by interdisciplinarity of astronomy and the importance of these observations. Working groups were formed by teachers and students, who organized the survey data, mobilizing the people in their cities. The results point ways about how to provide the scientific culture and the motivation to learn science in students, using approaches between the following communities: scientific, amateur and school. En este artículo se describe cómo 67 profesores de 23 ciudades, despertó el interés científico en los estudiantes mediante un fenómeno astronómico: un eclipse total de Luna. Antes y después del eclipse, reuniones para la formación continua se centraron en la interdisciplinariedad de la astronomía, y la importancia de las observaciones de este tipo de fenómeno. Profesores y estudiantes formaron grupos de trabajo para investigar datos durante el eclipse, con el participación de la comunidad en sus ciudades. Los resultados apuntan a las opciones que conducen a la cultura científica y la motivación para aprender la ciencia, utilizando las relaciones de los siguientes grupos: científicos, aficionados y la escuela. Este texto relata como 67 professores, provenientes de 23 cidades, puderam despertar, nos alunos, o interesse científico utilizando um fenômeno natural astronômico: um eclipse lunar total. O evento foi precedido e procedido por encontros de formação continuada, onde se caracterizou a interdisciplinaridade da astronomia e a importância das observações de fenômenos como estes. Grupos de trabalho foram formados por professores e alunos, que se organizaram para o levantamento conjunto de dados durante o fenômeno, além do envolvimento da comunidade em suas respectivas cidades. Os resultados apontam

  20. Lab Astro and the Origins of the Chemical Elements

    Science.gov (United States)

    Lawler, James E.

    2010-03-01

    . Suppl. Ser. 182, 51-79 (2009). [0pt] [3] J. Simmerer, C. Sneden, J. J. Cowan, J. Collier, V. M. Woolf, and J. E. Lawler, Astrophys. J. 617, 1091-1114 (2004). [0pt] [4] A. McWilliam, Ann. Rev. Astron. & Astrophys. 35, 503 (1997). [0pt] [5] M. Asplund, Ann. Rev. Astron. & Astrophys. 43, 481 (2005).

  1. Detecting signatures of cosmological recombination and reionization in the cosmic radio background

    Science.gov (United States)

    Subrahmanyan, Ravi; Shankar Narayana Rao, Udaya; Sathyanarayana Rao, Mayuri; Singh, Saurabh

    2015-08-01

    Evolution of the baryons during the Epochs of cosmological Recombination and Reionization has left traces in the cosmic radio background in the form of spectral distortions (Sunyaev & Chluba 2008 Astron. Nachrichten, 330, 657; Pritchard & Loeb 2012 Rep Prog Phys 75(8):086901). The spectral signature depends on the evolution in the ionization state in hydrogen and helium and on the spin temperature of hydrogen. These probe the physics of energy release beyond the last scattering surface at redshifts exceeding 1090 and the nature of the first sources and gas evolution down to redshift about 6. The spectral distortions are sensitive to the nature of the first stars, ultra-dwarf galaxies, accreting compact objects, and the evolving ambient radiation field: X-rays and UV from the first sources. Detection of the all-sky or global spectral distortions in the radio background is hence a probe of cosmological recombination and reionization.We present new spectral radiometers that we have purpose designed for precision measurements of spectral distortions at radio wavelengths. New antenna elements include frequency independent and electrically small fat-dipole (Raghunathan et al. 2013 IEEE TAP, 61, 3411) and monopole designs. Receiver configurations have been devised that are self-calibratable (Patra et al. 2013 Expt Astron, 36, 319) so that switching of signal paths and of calibration noise sources provide real time calibration for systematics and receiver noise. Observing strategies (Patra et al. arXiv:1412.7762) and analysis methods (Satyanarayana Rao et al. arXiv:1501.07191) have been evolved that are capable of discriminating between the cosmological signals and the substantially brighter foregrounds. We have also demonstrated the value of system designs that exploit advantages of interferometer detection (Mahesh et al. arXiv:1406.2585) of global spectral distortions.Finally we discuss how the Square Kilometer Array stations may be outfitted with precision spectral

  2. DROMO propagator revisited

    Science.gov (United States)

    Urrutxua, Hodei; Sanjurjo-Rivo, Manuel; Peláez, Jesús

    2016-01-01

    In the year 2000 an in-house orbital propagator called DROMO (Peláez et al. in Celest Mech Dyn Astron 97:131-150, 2007. doi: 10.1007/s10569-006-9056-3) was developed by the Space Dynamics Group of the Technical University of Madrid, based in a set of redundant variables including Euler-Rodrigues parameters. An original deduction of the DROMO propagator is carried out, underlining its close relation with the ideal frame concept introduced by Hansen (Abh der Math-Phys Cl der Kon Sachs Ges der Wissensch 5:41-218, 1857). Based on the very same concept, Deprit (J Res Natl Bur Stand Sect B Math Sci 79B(1-2):1-15, 1975) proposed a formulation for orbit propagation. In this paper, similarities and differences with the theory carried out by Deprit are analyzed. Simultaneously, some improvements are introduced in the formulation, that lead to a more synthetic and better performing propagator. Also, the long-term effect of the oblateness of the primary is studied in terms of DROMO variables, and new numerical results are presented to evaluate the performance of the method.

  3. Global positioning system theory and practice

    CERN Document Server

    Hofmann-Wellenhof, Bernhard; Collins, James

    2001-01-01

    This book is dedicated to Dr. Benjamin William Remondi for many reasons. The project of writing a Global Positioning System (GPS) book was con­ ceived in April 1988 at a GPS meeting in Darmstadt, Germany. Dr. Remondi discussed with me the need for an additional GPS textbook and suggested a possible joint effort. In 1989, I was willing to commit myself to such a project. Unfortunately, the timing was less than ideal for Dr. Remondi. Therefore, I decided to start the project with other coauthors. Dr. Remondi agreed and indicated his willingness to be a reviewer. I selected Dr. Herbert Lichtenegger, my colleague from the Technical University Graz, Austria, and Dr. James Collins from Rockville, Maryland, U.S.A. In my opinion, the knowledge ofthe three authors should cover the wide spectrum of GPS. Dr. Lichtenegger is a geodesist with broad experience in both theory and practice. He has specialized his research to geodetic astron­ omy including orbital theory and geodynamical phenomena. Since 1986, Dr. Lichteneg...

  4. Determination of reddening and age for ten Large Magellanic Cloud star clusters from integrated spectroscopy

    CERN Document Server

    Ahumada, Andrea V; Clariá, Juan J; Oddone, Mónica A; Palma, Tali

    2016-01-01

    We present flux-calibrated integrated spectra in the optical range (3700-6800 \\AA) obtained at Complejo Astron\\'omico El Leoncito (CASLEO, Argentina) for a sample of 10 concentrated star clusters belonging to the Large Magellanic Cloud (LMC). No previous data exist for two of these objects (SL 142 and SL 624), while most of the remaining clusters have been only poorly studied. We derive simultaneously foreground $E(B-V)$ reddening values and ages for the cluster sample by comparing their integrated spectra with template LMC cluster spectra and with two different sets of simple stellar population models. Cluster reddening values and ages are also derived from both available interstellar extinction maps and by using diagnostic diagrams involving the sum of equivalent widths of some selected spectral features and their calibrations with age, respectively. For the studied sample, we derive ages between 1 Myr and 240 Myr. In an effort to create a spectral library at the LMC metallicity level with several clusters ...

  5. Observed IRIS Profiles of the h and k Doublet of Mg ii and Comparison with Profiles from Quiescent Prominence NLTE Models

    Science.gov (United States)

    Vial, Jean-Claude; Pelouze, Gabriel; Heinzel, Petr; Kleint, Lucia; Anzer, Ulrich

    2016-01-01

    With the launch of the Interface Region Imaging Spectrograph (IRIS) mission, it is now possible to obtain high-resolution solar prominence spectra and to begin to distinguish the contributions of the many (apparent or not) threads that structure prominences. We aim at comparing unique observations obtained in the Mg ii h and k lines of a polar crown prominence with the radiative outputs from one-dimensional models built with non-local-thermodynamic equilibrium codes (Heinzel et al. Astron. Astrophys. 564, A132, 2014). We characterize the profiles obtained through thorough calibration procedures, with attention paid to the absolute values, full-width at half-maximum, and the ratio of k to h intensities. We also show that at the top of some structures, line-of-sight velocities of about 9 km s^{-1} can be detected. We find a range of static, low-pressure, low-thickness, low-temperature models that could fit k or h observed values, but that cannot satisfy the low observed k/h ratio. We investigate whether these low values might be explained by the inclusion of horizontal flows in small-scale threads. These flows are also necessary in another class of models, where the pressure is kept low but thickness and temperature are increased up to the observed thickness and up to 15 000 K.

  6. Distribución espacial de órbitas con diferentes grados de caoticidad en modelos autoconsistentes de satélites galácticos

    Science.gov (United States)

    Muzzio, J. C.; Mosquera, M.

    En trabajos anteriores (Carpintero et al., Cel. Mech. Dynam. Astron. 85, 247, 2003), mostramos que las órbitas caóticas son muy importantes en los satélites galácticos. Sin embargo, los únicos modelos autoconsistentes de los que se disponía para ellos eran los de Heggie-Ramamani, cuya función de distribución depende sólo de la energía por lo que no mostraban diferencias entre las distribuciones de sus órbitas regulares y caóticas. Ahora, mediante una aproximación cuadrupolar, hemos logrado construir modelos autoconsistentes de satélites galácticos con distribuciones de velocidades anisotrópicas (lo que indica que sus funciones de distribución no dependen sólo de la energía) y hemos logrado revelar las diferencias entre las estructuras espaciales de las órbitas de distinta caoticidad.

  7. On the jets, kinks, and spheromaks formed by a planar magnetized coaxial gun

    International Nuclear Information System (INIS)

    Measurements of the various plasma configurations produced by a planar magnetized coaxial gun provide insight into the magnetic topology evolution resulting from magnetic helicity injection. Important features of the experiments are a very simple coaxial gun design so that all observed geometrical complexity is due to the intrinsic physical dynamics rather than the source shape and use of a fast multiple-frame digital camera which provides direct imaging of topologically complex shapes and dynamics. Three key experimental findings were obtained: (1) formation of an axial collimated jet [Hsu and Bellan, Mon. Not. R. Astron. Soc. 334, 257 (2002)] that is consistent with a magnetohydrodynamic description of astrophysical jets (2) identification of the kink instability when this jet satisfies the Kruskal-Shafranov limit, and (3) the nonlinear properties of the kink instability providing a conversion of toroidal to poloidal flux as required for spheromak formation by a coaxial magnetized source [Hsu and Bellan, Phys. Rev. Lett. 90, 215002 (2003)]. An interpretation is proposed for how the n=1 central column instability provides flux amplification during spheromak formation and sustainment, and it is shown that jet collimation can occur within one rotation of the background poloidal field

  8. Las manifestaciones naturales como indicadores del calendario bosquesino

    Directory of Open Access Journals (Sweden)

    Napoleón Vela Mendoza

    2014-09-01

    Full Text Available Este artículo presenta un inventario del conocimiento de los bosquesinos (habitantes rurales de la selva amazónica que viven en el bosque y del bosque y sus aguas de la región de bajo río Ucayali (Amazonia peruana sobre las manifestaciones astronómicas, climatológicas, hidrográficas y biológicas con las que se ubican en el ritmo de las estaciones y orientan sus actividades en el medio natural. Las poblaciones bosquesinas distinguen dos periodos o épocas: la época de vaciante o de sol, y la época de creciente o de lluvias. Estas épocas a su vez se dividen en cuatro estaciones principales: Verano chico (mayo-junio, aguas en descenso, Verano grande (julio-octubre, Invierno chico (noviembre-diciembre, inicio de la creciente e Invierno grande (enero-abril. Incluye un glosario con la identificación biológica y las definiciones de 183 nombres de animales, plantas y expresiones del español local.

  9. The Expanding Nebular Remnant of the Recurrent Nova RS Ophiuchi (2006): II. Modeling of Combined Hubble Space Telescope Imaging and Ground-based Spectroscopy

    CERN Document Server

    Ribeiro, V A R M; Darnley, M J; Harman, D J; Newsam, A M; O'Brien, T J; Bohigas, J; Echevarría, J M; Bond, H E; Chavushyan, V H; Costero, R; Coziol, R; Evans, A; Eyres, S P S; León-Tavares, J; Richer, M G; Tovmassian, G; Starrfield, S; Zharikov, S V

    2009-01-01

    We report Hubble Space Telescope imaging, obtained 155 and 449 days after the 2006 outburst of the recurrent nova RS Ophiuchi, together with ground-based spectroscopic observations, obtained from the Observatorio Astron\\'omico Nacional en San Pedro M\\'artir, Baja California, M\\'exico and at the Observatorio Astrof\\'isico Guillermo Haro, at Cananea, Sonora, M\\'exico. The observations at the first epoch were used as inputs to model the geometry and kinematic structure of the evolving RS Oph nebular remnant. We find that the modeled remnant comprises two distinct co-aligned bipolar components; a low-velocity, high-density innermost (hour glass) region and a more extended, high-velocity (dumbbell) structure. This overall structure is in agreement with that deduced from radio observations and optical interferometry at earlier epochs. We find that the asymmetry observed in the west lobe is an instrumental effect caused by the profile of the HST filter and hence demonstrate that this lobe is approaching the observer...

  10. Plasma Physics and Controlled Nuclear Fusion Research. Proceedings of the Third International Conference on Plasma Physics and Controlled Nuclear Fusion Research. Vol. I

    International Nuclear Information System (INIS)

    Proceedings of the Third Conference on this matter convened by the IAEA and held at Novosibirsk, 1-7 August 1968. The meeting was attended by more than 400 participants from 24 countries. Contents: (Vol. I) Summary of the Conference (4 papers); Shock waves (8 papers); Toroidal confinement I (Tokamak, Zeta, etc.) (11 papers); Toroidal confinement II (Multipoles, etc.) (9 papers) ; Toroidal confinement III (Stellarators) (9 papers) ; Drift waves and non-linear phenomena (15 papers); Toroidal confinement IV (Theory), Laser-produced plasmas, Astron (9 papers). (Vol. II) Plasma focus, Confinement by neutral gas. Instabilities and waves (6 papers); Open-ended systems I (Mirrors) (11 papers) ; HF heating, confinement and stabilization (13 papers); Open-ended systemsII (Theta pinch)(12 papers); Turbulent heating, Beam-plasma interaction (10 papers). Each paper is in its original language (80 English, 37 Russian and 10 French) and is preceded by an abstract in English with one in the original language if this is not English. The discussions are in English. (author)

  11. The Science Teachers and Their way of Thinking about Astronomy. (Spanish Title: Los Profesores de Ciencias y Sus Formas de Pensar la Astronomía.) Os Professores de Ciências e Suas Formas de Pensar a Astronomia

    Science.gov (United States)

    Leite, Cristina; Hosoume, Yassuko

    2007-12-01

    The research presented in this article is about the way science teachers from Elementary School think about astronomical elements. Its methodology is based on semi-structured interviews, which were video recorded. The research is centered in a three-dimensional perspective of astronomical Earth, the Sun, the Moon, the planets and the stars, and also the conceptions about sky and Universe. The esults indicate a Universe that contains: Sun, stars, planets and Moon; where the Solar System is a little part of the whole. Sometimes they think that the Solar System is the Universe. The objects are in the sky or in the Universe, which, for many of them, is only the space above the Earth. The flat shape of astronomical objects and the spatial structure of the Universe are striking features. Many of them think that Sun and stars are different: the Sun is a hot object and the stars are cold ones. These results worry us and they certainly indicate how urgent it is to plan Professional Development in Astronomy for teachers, after all the PCN's emphasize that this subject is important to be taught. El objeto de investigación de este artículo es la manera de pensar sobre los elementos de la Astronomía de los profesores de Ciencias en la enseñanza fundamental. La metodología consiste en entrevistas semi-estructuradas, filmadas en video y centradas en la tridimensionalidad de los elementos astronómicos, para posibilitar un mapeamiento de las concepciones sobre las formas y dimensiones de la Tierra, del Sol, de la Luna, de los planetas y de las estrellas, como también de la concepción de cielo y de Universo en su totalidad. Los resultados indican un Universo conteniendo: Sol, estrellas, planetas y Luna, donde el Sistema Solar se ubica como parte. Algunas veces, el Universo es concebido como el propio Sistema Solar. Los objetos están en el cielo o en el Universo, que, para muchos, se restringe al espacio que está arriba de la Tierra. La forma plana de los objetos astron

  12. HAMC2 ASTROMETRY AND PHOTOMETRY CALIBRATION AND COMPARISON OF ITS DATA WITH THOSE OF OTHER MODERN CCD CATALOGUES

    Directory of Open Access Journals (Sweden)

    J. L. Muiños

    2008-01-01

    Full Text Available El segundo Cat logo Meridiano Hispano-Argentino (HAMC2 consta de m s de 12.500.000 de posiciones y magnitudes de estrellas m s brillantes que la magnitud V=16.5 y con declinaciones comprendidas entre -30 y 0 . Est calculado a partir de las observaciones CCD del C rculo Meridiano Automatico de San Fernando (CMASF instalado en la actualidad en el Observatorio Carlos U. Cesco (CUC en San Juan (Argentina. El CMASF es operado conjuntamente por el Real Instituto y Observatorio de la Armada (ROA de Espa a, propietario del instrumento, y el Observatorio Astron mico F lix Aguilar (OAFA de la Universidad Nacional de San Juan (Argentina, al que pertenece el CUC. La publicaci n del cat logo est prevista para el primer semestre de 2008. En esta comunicaci n presentamos los trabajos llevados a cabo para la formaci n del HAMC2, la calibraci n del sensor de su c mara CCD y nalmente la comparaci n de sus resultados astrometricos y fotom tricos con otros cat logos CCD actuales con el n de detectar y eliminar posibles errores sistem ticos.

  13. The stability of stratified spatially periodic shear flows at low Péclet number

    International Nuclear Information System (INIS)

    This work addresses the question of the stability of stratified, spatially periodic shear flows at low Péclet number but high Reynolds number. This little-studied limit is motivated by astrophysical systems, where the Prandtl number is often very small. Furthermore, it can be studied using a reduced set of “low-Péclet-number equations” proposed by Lignières [“The small-Péclet-number approximation in stellar radiative zones,” Astron. Astrophys. 348, 933–939 (1999)]. Through a linear stability analysis, we first determine the conditions for instability to infinitesimal perturbations. We formally extend Squire’s theorem to the low-Péclet-number equations, which shows that the first unstable mode is always two-dimensional. We then perform an energy stability analysis of the low-Péclet-number equations and prove that for a given value of the Reynolds number, above a critical strength of the stratification, any smooth periodic shear flow is stable to perturbations of arbitrary amplitude. In that parameter regime, the flow can only be laminar and turbulent mixing does not take place. Finding that the conditions for linear and energy stability are different, we thus identify a region in parameter space where finite-amplitude instabilities could exist. Using direct numerical simulations, we indeed find that the system is subject to such finite-amplitude instabilities. We determine numerically how far into the linearly stable region of parameter space turbulence can be sustained

  14. The LOFAR Pulsar Data Pipeline

    Science.gov (United States)

    Alexov, A.; Hessels, J.; Mol, J. D.; Stappers, B.; van Leeuwen, J.

    2010-12-01

    The LOw Frequency ARray (LOFAR) for radio astronomy is being built in the Netherlands by ASTRON, with extensions throughout Europe. LOFAR operates at radio frequencies below 250 MHz. The project is an interferometric array of radio antennas grouped into stations that are distributed over an area of hundreds of kilometers. LOFAR will revolutionise low-frequency radio astronomy. Transient radio phenomena and pulsars are one of six LOFAR Key Science Projects (KSPs). As part of the Transients KSP, the Pulsar Working Group has been developing the LOFAR Pulsar Data Pipeline to both study known pulsars as well as search for new ones. The pipeline is being developed for the Blue Gene/P (BG/P) supercomputer and a large Linux cluster in order to utilize enormous amounts of computation capabilities (˜ 50 Tflops) and data streams of up to 23TB/hour. The LOFAR pipeline output will be using the Hierarchical Data Format 5 (HDF5) to efficiently store large amounts of numerical data, and to manage complex data encompassing a variety of data types, across distributed storage and processing architectures. We present the LOFAR Pulsar Data Pipeline overview, the pulsar beam-formed data format, the status of the pipeline processing as well as our future plans for developing additional transient pipelines.

  15. The San Pedro M\\'artir Planetary Nebula Kinematic Catalogue: Extragalactic Planetary Nebulae

    CERN Document Server

    Richer, M G; Díaz-Méndez, E; Riesgo, H; Báez, S -H; García-Díaz, Ma -T; Meaburn, J; Clark, D M; Olvera, R M Calderón; Soto, G López; Rebolo, O Toledano

    2010-01-01

    We present kinematic data for 211 bright planetary nebulae in eleven Local Group galaxies: M31 (137 PNe), M32 (13), M33 (33), Fornax (1), Sagittarius (3), NGC 147 (2), NGC 185 (5), NGC 205 (9), NGC 6822 (5), Leo A (1), and Sextans A (1). The data were acquired at the Observatorio Astron\\'omico Nacional in the Sierra de San Pedro M\\'artir using the 2.1m telescope and the Manchester Echelle Spectrometer in the light of [\\ion{O}{3}]$\\lambda$5007 at a resolution of 11 km/s. A few objects were observed in H$\\alpha$. The internal kinematics of bright planetary nebulae do not depend strongly upon the metallicity or age of their progenitor stellar populations, though small systematic differences exist. The nebular kinematics and H$\\beta$ luminosity require that the nebular shells be accelerated during the early evolution of their central stars. Thus, kinematics provides an additional argument favoring similar stellar progenitors for bright planetary nebulae in all galaxies.

  16. The Acceleration of the Nebular Shells in Planetary Nebulae in the Milky Way Bulge

    CERN Document Server

    Richer, Michael G; Pereyra, Margarita; Riesgo, Hortensia; Diaz, Maria Teresa Garcia; Baez, Sol-Haret

    2008-01-01

    We present a systematic study of line widths in the [\\ion{O}{3}]$\\lambda$5007 and H$\\alpha$ lines for a sample of 86 planetary nebulae in the Milky Way bulge based upon spectroscopy obtained at the \\facility{Observatorio Astron\\'omico Nacional in the Sierra San Pedro M\\'artir (OAN-SPM)} using the Manchester Echelle Spectrograph. The planetary nebulae were selected with the intention of simulating samples of bright extragalactic planetary nebulae. We separate the planetary nebulae into two samples containing cooler and hotter central stars, defined by the absence or presence, respectively, of the \\ion{He}{2} $\\lambda$6560 line in the H$\\alpha$ spectra. This division separates samples of younger and more evolved planetary nebulae. The sample of planetary nebulae with hotter central stars has systematically larger line widths, larger radii, lower electron densities, and lower H$\\beta$ luminosities. The distributions of these parameters in the two samples all differ at significance levels exceeding 99%. These dif...

  17. Oxygen Chemistry in Titan's Atmosphere

    Science.gov (United States)

    Wilson, E. H.; Atreya, S. K.

    2002-09-01

    Oxygen chemistry in the atmosphere of Titan is controlled by the presence of CO and a likely influx of extraplanetary oxygen. The presence of water vapor, corroborated by the Infrared Space Observatory (ISO) stratospheric detection [1], combined with CO induces the formation of CO2, which has also been observed [2]. However, the high CO/H2O ratio in Titan's atmosphere causes the propagation of oxygen chemistry to follow a different path than what is predicted for the Jovian planets. Specifically, the efficient CO recycling mechanisms serve to inhibit significant formation of larger oxygen compounds such as CH3OH (methanol) and CH2CO (ketene). The results of a 1-D photochemical model are presented in the context of identifying possible oxygen compounds that might be detected by the Cassini/Huygens mission which will arrive at Titan in 2004. This work was supported by the NASA Planetary Atmospheres Program and by the GCMS Project of the Cassini/Huygens mission. [1] A. Coustenis et al., Astron. Astrophys., 336, L85-L89, 1998. [2] A. Coustenis et al., Icarus, 80, 54-76, 1989.

  18. ATMOSPHERIC AEROSOL VARIABILITY OVER THE REGION OF SAN PEDRO MÁRTIR FROM MODIS DATA

    Directory of Open Access Journals (Sweden)

    Mario R. Araiza Quijano

    2011-01-01

    Full Text Available Se presenta un estudio del espesoróptico del aerosol atmosférico (AOT por sus siglas en inglés en el sitio astronómico de San Pedro Mártir, B. C., México durante el periodo 2000-2008. Las mediciones del AOT se realizaron con el instrumento Moderate Resolution Imaging Spectroradiometer (MODIS, a bordo de los satélites Aqua y Terra de la NASA. Se han identificado valores característicos estacionales que muestran un comportamiento de mayor transparencia atmosférica durante el otoño. Las mejores condiciones de transparencia atmosférica ocurren durante octubre y noviembre. El comportamiento anual durante 2000-2008 del AOT de MODIS da valores promedio de 0.147±0.103, 0.128±0.090, 0.115±0.081, 0.087 ± 0.066 en 4700, 5500, 6600 and 21300 A, respectivamente. Utilizando estos valores promedio se analizó la dependencia del AOT con la longitud de onda, y se encontró que OIR 0.31 ± 0.06 y la relación 0.00610.31 para dispersión por aerosoles en el sitio de San Pedro Mártir.

  19. Foco Nasmyth para el telescopio 2,15mts. de CASLEO

    Science.gov (United States)

    Casagrande, A. R.

    En principio, este proyecto intenta lograr el mayor aprovechamiento posible del instrumental que se dispone, buscando la manera de optimizar y hacer más eficiente el servicio que brinda el CASLEO a la comunidad astronómica. El mismo consiste en utilizar dispositivos ya existentes en el telescopio, y darle una utilidad. Tal es el caso del camino óptico destinado al foco Coude. Si tenemos en cuenta que disponemos de un tercer espejo Coude, con todos sus mecanismos automatizados, (actualmente sin uso), una distancia apropiada del plano focal, el espacio y el lugar físico necesario para instalar un periférico, es posible la habilitación de un foco Nasmyth en el telescopio 2,15mts. El hecho de contar con este nuevo foco, redundará en importantes beneficios. En primer lugar, posibilitará la observación, casi simultánea, con dos instrumentos. Otro aspecto a tener en cuenta, es que disminuirá el frecuente cambio del instrumental periférico, motivo este que degrada su ideal puesta a punto. Por último, también de interés, es de destacar su escaso costo de ejecución.

  20. Sobre el ciclo maya de 819 días

    Directory of Open Access Journals (Sweden)

    Huberto Quiñones Garza

    2011-01-01

    Full Text Available Algunos autores consideran que los mayas manejaban un ciclo de 819 días, que habría tenido un carácter mágico o ritual, sin descartar alguna manifestación astrológica o astronómica. Un enfoque que no ha sido tomado en cuenta hasta hoy, es el puramente aritmético, el posible interés del sacerdocio maya en este número como tal. Se especula aquí que el número 819 está relacionado con el valor de TT, además de la probable vinculación que esta cifra podría guardar con sus sistemas numérico y calendárico. Dos situaciones se vislumbran como importantes contribuciones, el planteamiento epistemológico implícito y los resultados obtenidos como información básica para futuras investigaciones dentro de la etnomatemática y la antropología.

  1. Morfología de la Coma del Cometa Hale - Bopp

    Science.gov (United States)

    Gil-Hutton, R.; Caballero, M.; Coldwell, G.; Cañada, M.; Godoy, G.; Trozzo, C.; Gómez, G.

    Para lograr comprender plenamente los procesos físicos que se desarrollan en los núcleos cometarios y obtener un modelo que explique, no sólo su actividad, sino también sus efectos sobre la coma, es necesario obtener información detallada para el mayor número de cometas posible, siendo las características más interesantes para estudiar la ubicación de las regiones activas, la presencia de jets, las tasas de producción de gas y polvo y la interacción de la coma con el viento solar. En la actualidad, con técnicas de procesamiento de imágenes y tecnología CCD se pueden obtener este tipo de datos para cometas que ingresan al sistema solar interior y estudiar, de esta manera, la morfología de sus comas, tratando de correlacionar la actividad detectada con algún modelo teórico. En este trabajo se presenta un estudio parcial de la actividad desarrollada por el cometa Hale-Bopp, y sus efectos sobre la morfología de su coma, desde agosto de 1995 hasta la fecha en base a imágenes adquiridas con el telescopio de 0.76 m. de la Estación Astronómica Dr. Carlos Ulrrico Cesco.

  2. Surface layer seeing at san Pedro Mártir revisited

    Directory of Open Access Journals (Sweden)

    L. J. Sánchez

    2007-01-01

    Full Text Available Reportamos medidas de la contribución de la capa superficial (2.3 a 15 m al seeing óptico en el Observatorio Astronómico Nacional de San Pedro M_artir (OAN-SPM. Utilizamos un mástil con sensores de temperatura microdiferenciales localizados a 7 diferentes alturas, para medir la constante de estructura del índice de refracción C2 n en los primeros 15 m. El parámetro de distorsión de la imagen (llamado comúnmente seeing integrado se determinó utilizando un Monitor Diferencial de Movimiento de Imagen (DIMM durante 23 noches, encontrándose una estadística log-normal con una mediana de 0:0084. El seeing promedio debido a la capa superficial fue de 0:0016. La turbulencia óptica de esta capa tiene una contribución promedio de 5.2% del C2 n total, lo cual corresponde a una degradación promedio de 3.2% del seeing total. Estos valores son similares a los encontrados en otros observatorios en el mundo, lo que sugiere que la presencia de árboles en el sitio del OAN-SPM no influye de manera considerable en el seeing debido a la capa superficial

  3. Development of a generalized scidar at UNAM

    Directory of Open Access Journals (Sweden)

    D. X. Cruz

    2003-01-01

    Full Text Available Un SCIDAR Generalizado est a siendo desarrollado en la Universidad Nacional Aut onoma de M exico, para el monitoreo de per les de turbulencia optica y de velocidad del viento en sitios astron omicos. Se reportan las especi caciones, dise~no y estado del proyecto. Los aspectos innovadores de este instrumento consisten principalmente en: 1 la utilizaci on de un detector CCD de bajo ruido de lectura y alta e ciencia cu antica sin intensi cador de imagen, lo cual aumenta el cociente se~nal a ruido y la magnitud l mite de las fuentes observables con respecto a otros instrumentos tipo SCIDAR operacionales; 2 el processamiento de im agenes que se realiza en tiempo real en una computadora personal bajo el sistema operativo Linux. Paralelamente al desarrollo instrumental, un simulador num erico est a siendo programado. El objetivo de dicho programa es investigar posibles efectos instrumentales. Se describe el Simulador de SCIDAR y se presentan algunos de sus resultados.

  4. 3D Spectroscopy of Local Luminous Compact Blue Galaxies: Kinematics of NGC 7673

    CERN Document Server

    Pérez-Gallego, J; Castillo-Morales, A; Castander, F J; Gallego, J; Garland, C A; Gruel, N; Pisano, D J; Sánchez, S F; Zamorano, J

    2009-01-01

    The kinematic properties of the ionized gas of local Luminous Compact Blue Galaxy (LCBG) NGC 7673 are presented using three dimensional data taken with the PPAK integral field unit at the 3.5-m telescope in the Centro Astron\\'omico Hispano Alem\\'an. Our data reveal an asymmetric rotating velocity field with a peak to peak difference of 60 km s$^{-1}$. The kinematic centre is found to be at the position of a central velocity width maximum ($\\sigma=54\\pm1$ km s$^{-1}$), which is consistent with the position of the luminosity-weighted centroid of the entire galaxy. The position angle of the minor rotation axis is 168$^{\\circ}$ as measured from the orientation of the velocity field contours. At least two decoupled kinematic components are found. The first one is compact and coincides with the position of the second most active star formation region (clump B). The second one is extended and does not have a clear optical counterpart. No evidence of active galactic nuclei activity or supernovae galactic winds poweri...

  5. The Narrow-Field Telescope Science Case: A Proposal

    Directory of Open Access Journals (Sweden)

    Michael G. Richer

    2007-01-01

    Full Text Available Basado en las capacidades observacionales que supuestamente estarán disponibles desde tierra y el espacio alrededor de 2015-2020, así como los intereses tradicionales de la comunidad astronómica mexicana, propongo que el telescopio de campo angosto (NFT esté dedicado a la espectroscopía de alta resolución, cubriendo el intervalo espectral que va desde el óptico hasta el infrarrojo medio, y a la imagen directa y espectroscopía (de mediana a alta resolución con óptica adaptativa en el infrarrojo cercano. Estas capacidades permitirán el estudio de los procesos responsables de la evolución galáctica después de la época de la acumulación de la masa: el desarrollo de la estructura galáctica, la formación y estructura estelar, la distribución de masas estelares, la cinemática y composición química de las estrellas y del medio interestelar

  6. Kinematic study of planetary nebulae in NGC 6822

    CERN Document Server

    Flores-Durán, S N; Hernández-Martínez, L; García-Rojas, J; Ruiz, M T

    2014-01-01

    By measuring precise radial velocities of planetary nebulae (which belong to the intermediate age population), H II regions, and A-type supergiant stars (which are members of the young population) in NGC 6822, we aim to determine if both types of population share the kinematics of the disk of H I found in this galaxy. Spectroscopic data for four planetary nebulae were obtained with the high spectral resolution spectrograph Magellan Inamori Kyocera Echelle (MIKE) on the Magellan telescope at Las Campanas Observatory. Data for other three PNe and one H II region were obtained from the SPM Catalog of Extragalactic Planetary Nebulae which employed the Manchester Echelle Spectrometer attached to the 2.1m telescope at the Observatorio Astron\\'omico Nacional, M\\'exico. In the wavelength calibrated spectra, the heliocentric radial velocities were measured with a precision better than 5-6 km s$^{-1}$. Data for three additional H II regions and a couple of A-type supergiant stars were collected from the literature. The...

  7. Radio Astronomy Transformed: Aperture Arrays - Past, Present & Future

    CERN Document Server

    Garrett, Michael A

    2012-01-01

    I review the early development of Aperture Arrays and their role in radio astronomy. The demise of this technology at the end of the 1960's, and the reasons for the rise of parabolic dishes is also considered. The parallels with the Antikythera mechanism (see these proceedings) as a lost technology are briefly presented. Aperture Arrays re-entered the world of radio astronomy as the idea to build a huge radio telescope with a collecting area of one square kilometre (the Square Kilometre Array, SKA) arose. Huge ICT technology advances had transformed Aperture Arrays in terms of their capability, flexibility and reliability. In the mid-1990s, ASTRON started to develop and experiment with the first high frequency aperture array tiles for radio astronomy - AAD, OSMA, THEA & EMBRACE. In the slipstream of these efforts, Phased Array Feeds (PAFs) for radio astronomy were invented and LOFAR itself emerged as a next generation telescope and a major pathfinder for the SKA. Meanwhile, the same advantages that apertu...

  8. XMM-Newton, powerful AGN winds and galaxy feedback

    Science.gov (United States)

    Pounds, K.; King, A.

    2016-06-01

    The discovery that ultra-fast ionized winds - sufficiently powerful to disrupt growth of the host galaxy - are a common feature of luminous AGN is major scientific breakthrough led by XMM-Newton. An extended observation in 2014 of the prototype UFO, PG1211+143, has revealed an unusually complex outflow, with distinct and persisting velocities detected in both hard and soft X-ray spectra. While the general properties of UFOs are consistent with being launched - at the local escape velocity - from the inner disc where the accretion rate is modestly super-Eddington (King and Pounds, Ann Rev Astron Astro- phys 2015), these more complex flows have raised questions about the outflow geometry and the importance of shocks and enhanced cooling. XMM-Newton seems likely to remain the best Observatory to study UFOs prior to Athena, and further extended observations, of PG1211+143 and other bright AGN, have the exciting potential to establish the typical wind dynamics, while providing new insights on the accretion geometry and continuum source structure. An emphasis on such large, coordinated observing programmes with XMM-Newton over the next decade will continue the successful philosophy pioneered by EXOSAT, while helping to inform the optimum planning for Athena

  9. Plasma Physics and Controlled Nuclear Fusion Research. Proceedings of the Third International Conference on Plasma Physics and Controlled Nuclear Fusion Research. Vol. II

    International Nuclear Information System (INIS)

    Proceedings of the Third Conference on this matter convened by the IAEA and held at Novosibirsk, 1-7 August 1968. The meeting was attended by more than 400 participants from 24 countries. Contents: (Vol. I) Summary of the Conference (4 papers); Shock waves (8 papers); Toroidal confinement I (Tokamak, Zeta, etc.) (11 papers); Toroidal confinement II (Multipoles, etc.) (9 papers); Toroidal confinement III (Stellarators) (9 papers); Drift waves and non-linear phenomena (15 papers); Toroidal confinement IV (Theory) , Laser-produced plasmas, Astron (9 papers). (Vol. II) Plasma focus, Confinement by neutral gas. Instabilities and waves (16 papers); Open-ended systems I (Mirrors) (11 papers); HF heating, confinement and stabilization (13 papers); Open-ended systems II (Theta pinch) (12 papers); Turbulent heating, Beam-plasma interaction (10 papers). Each paper is in its original language (80 English, 37 Russian and 10 French) and is preceded by an abstract in English with one in the original language if this is not English. The discussions are in English. (author)

  10. Design of VLBI Array in South America

    Science.gov (United States)

    Carrara, E. A.; Abraham, Z.

    1990-11-01

    RESUMEN. Estudiamos la localizaci6n 6ptima de estaciones de \\ ras' en territorlo brasileno. Con una red VLBI de estaciones reales y ficti- cias simulamos observaciones. Se usan los datos generados de estps ex- perimentos para obtener Ia distribuci6n de brillo de radiofuentes fic- ticias por medlo de tecaicas de mapeo bIbrido. Se concluye que l mejor localizaci6n de estacionee'VLBI futuras, tomando en cuenta las estacio- nes de EUA y de Europa, se encuentra en el Norte-Noreste de razll. El analisis de los datos se hizo con los programas de CALTECH, los cuales estan instalados en una computadora VAX del Departamento de Astronomla del Instituto Astron6mico y Geoflsico de la Universidad de Sa"'o Paulo. ABSTRACT: In this work we study the optimum localization for future VLBI stations in the Brazilian territory. With a VLBI network of real and fictitious stations we make simulations of observations. The data generated in these experiments are used to obtain brightness distribution of a fictitious radio source by the hybrid mapping techniques. We conclude that the best localization of a future VLBI station taking into account the addition of US and European Stations, is roughly in North-Northeast sites in Brazil. The analysis of the data is made with the software of CALTECH, which is installed in the VAX computer of the Astronomy Department of Instituto e Geofisico - USP. Key `{` : INSTRUMENTS - INTERFEROMETRY

  11. Hydrodynamics associated to the X-ray light curve of A0620-00

    Science.gov (United States)

    Coronado, Y.; Mendoza, S.

    2015-12-01

    From 1975 to 1976, an outburst was detected in the light curve of the X-ray transient A0620-00 using the Ariel V and SAS-3 experiments. In this article we model the outburst with the hydrodynamical model proposed by Mendoza et al. (Mon. Not. R. Astron. Soc. 395:1403, 2009). The physical model is constructed assuming basic mass and momentum conservation laws associated to the motion of the shock waves developed inside the expanding relativistic jet of the source. These internal shock waves are produced as a result of periodic variations of the injected mass and velocity of the flow at the base of the jet. The observations of this X-ray light curve present two clear bumps. The first one is modelled assuming periodic variations of the injected velocity at the base of the jet, while the second one can either be modelled by further velocity oscillations, or by a periodic variation of the mass injection rate at the base of the jet at a latter time. This latter model is statistically more significant for the observed data, than the former. The fitting of the data fixes different parameters of the model, such as the mean mass injection rate at the base of the jet and the oscillation frequency of the flow as measured on the rest frame of the central source.

  12. The LOFAR pilot surveys for pulsars and fast radio transients

    Science.gov (United States)

    Coenen, Thijs; van Leeuwen, Joeri; Hessels, Jason W. T.; Stappers, Ben W.; Kondratiev, Vladislav I.; Alexov, A.; Breton, R. P.; Bilous, A.; Cooper, S.; Falcke, H.; Fallows, R. A.; Gajjar, V.; Grießmeier, J.-M.; Hassall, T. E.; Karastergiou, A.; Keane, E. F.; Kramer, M.; Kuniyoshi, M.; Noutsos, A.; Osłowski, S.; Pilia, M.; Serylak, M.; Schrijvers, C.; Sobey, C.; ter Veen, S.; Verbiest, J.; Weltevrede, P.; Wijnholds, S.; Zagkouris, K.; van Amesfoort, A. S.; Anderson, J.; Asgekar, A.; Avruch, I. M.; Bell, M. E.; Bentum, M. J.; Bernardi, G.; Best, P.; Bonafede, A.; Breitling, F.; Broderick, J.; Brüggen, M.; Butcher, H. R.; Ciardi, B.; Corstanje, A.; Deller, A.; Duscha, S.; Eislöffel, J.; Fender, R.; Ferrari, C.; Frieswijk, W.; Garrett, M. A.; de Gasperin, F.; de Geus, E.; Gunst, A. W.; Hamaker, J. P.; Heald, G.; Hoeft, M.; van der Horst, A.; Juette, E.; Kuper, G.; Law, C.; Mann, G.; McFadden, R.; McKay-Bukowski, D.; McKean, J. P.; Munk, H.; Orru, E.; Paas, H.; Pandey-Pommier, M.; Polatidis, A. G.; Reich, W.; Renting, A.; Röttgering, H.; Rowlinson, A.; Scaife, A. M. M.; Schwarz, D.; Sluman, J.; Smirnov, O.; Swinbank, J.; Tagger, M.; Tang, Y.; Tasse, C.; Thoudam, S.; Toribio, C.; Vermeulen, R.; Vocks, C.; van Weeren, R. J.; Wucknitz, O.; Zarka, P.; Zensus, A.

    2014-10-01

    We have conducted two pilot surveys for radio pulsars and fast transients with the Low-Frequency Array (LOFAR) around 140 MHz and here report on the first low-frequency fast-radio burst limit and the discovery of two new pulsars. The first survey, the LOFAR Pilot Pulsar Survey (LPPS), observed a large fraction of the northern sky, ~ 1.4 × 104 deg2, with 1 h dwell times. Each observation covered ~75 deg2 using 7 independent fields formed by incoherently summing the high-band antenna fields. The second pilot survey, the LOFAR Tied-Array Survey (LOTAS), spanned ~600 deg2, with roughly a 5-fold increase in sensitivity compared with LPPS. Using a coherent sum of the 6 LOFAR "Superterp" stations, we formed 19 tied-array beams, together covering 4 deg2 per pointing. From LPPS we derive a limit on the occurrence, at 142 MHz, of dispersed radio bursts of 107 Jy for the narrowest searched burst duration of 0.66 ms. In LPPS, we re-detected 65 previously known pulsars. LOTAS discovered two pulsars, the first with LOFAR or any digital aperture array. LOTAS also re-detected 27 previously known pulsars. These pilot studies show that LOFAR can efficiently carry out all-sky surveys for pulsars and fast transients, and they set the stage for further surveying efforts using LOFAR and the planned low-frequency component of the Square Kilometer Array. http://www.astron.nl/pulsars/lofar/surveys/lotas/

  13. DDOTI: the deca-degree optical transient imager

    CERN Document Server

    Watson, Alan M; Troja, Eleonora; Román-Zúñiga, Carlos G; Butler, Nathaniel R; Kutyrev, Alexander S; Gehrels, Neil A; Ángeles, Fernando; Basa, Stéphane; Blanc, Pierre-Eric; Boër, Michel; de Diego, Jose A; Farah, Alejandro S; Figueroa, Liliana; Chew, Yilen Gómez Maqueo; Klotz, Alain; Quirós, Fernando; Reyes-Ruíz, Maurico; Ruíz-Diáz-Soto, Jaime; Thierry, Pierre; Tinoco, Silvio

    2016-01-01

    DDOTI will be a wide-field robotic imager consisting of six 28-cm telescopes with prime focus CCDs mounted on a common equatorial mount. Each telescope will have a field of view of 12 square degrees, will have 2 arcsec pixels, and will reach a 10-sigma limiting magnitude in 60 seconds of r = 18.7 in dark time and r = 18.0 in bright time. The set of six will provide an instantaneous field of view of about 72 square degrees. DDOTI uses commercial components almost entirely. The first DDOTI will be installed at the Observatorio Astron\\'omico Nacional in Sierra San Pedro Mart\\'ir, Baja California, M\\'exico in early 2017. The main science goals of DDOTI are the localization of the optical transients associated with GRBs detected by the GBM instrument on the Fermi satellite and with gravitational-wave transients. DDOTI will also be used for studies of AGN and YSO variability and to determine the occurrence of hot Jupiters. The principal advantage of DDOTI compared to other similar projects is cost: a single DDOTI i...

  14. An initial meteoroid stream survey in the southern hemisphere using the Southern Argentina Agile Meteor Radar (SAAMER)

    Science.gov (United States)

    Janches, D.; Hormaechea, J. L.; Brunini, C.; Hocking, W.; Fritts, D. C.

    2013-04-01

    We present in this manuscript a 4 year survey of meteor shower radiants utilizing the Southern Argentina Agile Meteor Radar (SAAMER). SAAMER, which operates at the southern most region of South America, is a new generation SKiYMET system designed with significant differences from typical meteor radars including high transmitted power and an 8-antenna transmitting array enabling large detected rates at low zenith angles. We applied the statistical methodology developed by Jones and Jones (Jones, J., Jones, W. [2006]. Month. Not. R. Astron. Soc. 367, 1050-1056) to the data collected each day and compiled the results into 1 composite representative year at 1° resolution in Solar Longitude. We then search for enhancements in the activity which last for at least 3 days and evolve temporally as is expected from a meteor shower. Using this methodology, we have identified in our data 32 shower radiants, two of which were not part of the IAU commission 22 meteor shower working list. Recently, SAAMER's capabilities were enhanced by adding two remote stations to receive meteor forward scatter signals from meteor trails and thus enable the determination of meteoroid orbital parameters. SAAMER started recording orbits in January 2012 and future surveys will focus on the search for unknown meteor streams, in particular in the southern ecliptic sky.

  15. First Spectral Coverage of two regions on Ceres in the far-UV

    Science.gov (United States)

    Hendrix, Amanda R.; Vilas, Faith; Li, Jian-Yang

    2015-11-01

    We present the first spectral observations of Ceres in the far-ultraviolet, along with new measurements in the near-UV and visible, as measured by HST/STIS as part of Cycle 22, in August-September, 2015. The observations are motivated by early broad-band UV observations [1][2][3] suggesting a UV absorption centered near 260 nm along with a very strong increase in UV reflectance into the far-UV (~160 nm). We have observed two central longitudes of Ceres - near 0°W and 120°W (this latter area one of the regions in which Herschel detected water vapor) - using the G140L (~120-172 nm), G230L (~170-310 nm) and G430L (~300-570 nm) detectors. We use the data to test a prediction of graphitized carbon on the surface, and we look for signatures of water ice and/or water vapor.[1] Parker, J. W., S. A. Stern, P. C. Thomas, M. C. Festou, W. J. Merline, E. F. Young, R. P Binzel, L. A. Lebofsky (2002). Astron J. 123, 549[2] Li et al. (2006). Icarus 182: 143-160.[3] Rivkin, A. S., J.-Y. Li, R. E. Milliken, L. F. Lim, A. J. Lovell, B. E. Schmidt, L. A. McFadden, B. A. Cohen (2011). Space Sci Rev 163, 95.

  16. Conversations with Marcgrave: the Origin of Modern Astronomy in the Southern Hemisphere (Spanish Title: Conversando con Marcgrave: El Origen de la Astronomía Moderna en el Hemisferio Sur) Conversando Com Marcgrave: a Origem da Moderna Astronomia no Hemisfério Sul

    Science.gov (United States)

    Medeiros, Alexandre; Araújo, Fábio

    2005-12-01

    primer observatorio astronómico del hemisferio y autor de las primeras observaciones astronómicas sistemáticas utilizando telescopios de este lado del mundo. Nuestra "conversación" con Marcgrave es imaginada en el marco del Recife antiguo, lugar donde él vivió durante el período de Mauricio de Nassau, y reune algunos colegas profesores apasionados por la enseñanza de la Astronomía. La historia es contada, de esta forma, dentro de un clima ameno y hasta un poco divertido, si bien las informaciones históricas y conceptuales contenidas en ella están basadas en fuentes bibliográficas confiables, debidamente referenciadas al final del texto. Estas fuentes van desde la obra original de este científico, en la cual aparece su relato sobre la observación de un eclipse solar en Recife, pasando por obras clásicas respecto de él mismo, como la del profesor Juliano Moreira, hasta fuentes mucho más recientes como el influyente trabajo del profesor John North. Otros textos importantes referidos al período de la colonización holandesa en el Brasil, tales como las obras clásicas de Charles Boxer, Bouman y Boogaart entre otros, son también utilizados en la construcción de esta dramatización pedagógica que se refiere a un interesante capítulo de la Historia de la Astronomía. O ano de 2004 assinala os 400 anos do nascimento do conde Maurício de Nassau, um importante personagem da história do Brasil. O presente texto está relacionado com o período do domínio holandês em Pernambuco. O artigo tenta resgatar o começo do estudo da Astronomia no hemisfério Sul. Para tal, idealizamos uma dramatização de uma entrevista fictícia com o astrônomo alemão Georg Marcgrave, construtor do primeiro observatório astronômico deste hemisfério e autor das primeiras observações astronômicas sistemáticas com o uso de telescópios neste lado do mundo. Nossa "conversa" com Marcgrave é idealizada no cenário do Recife antigo, local em que ele viveu no período de Maur

  17. Observations and 3D Hydrodynamical models of planetary nebulae with Wolf Rayet type central stars

    CERN Document Server

    Rechy-García, J S; Peña, M; Raga, A C

    2016-01-01

    We present high-resolution, long-slit spectroscopic observations of two planetary nebulae with [WC] central stars located near the galactic bulge, M 1-32 and M 3-15. The observations were obtained with the 2.1-m telescope at the Observatorio Astron\\'omico Nacional, San Pedro M\\'artir. M 1-32 shows wide wings on the base of its emission lines and M 3-15 has two very faint high-velocity knots. In order to model both PNe we built a three-dimensional model consisting of a jet interacting with an equatorially concentrated slow wind, emulating the presence of a dense torus, using the Yguaz\\'u hydrodynamical code. From our hydrodynamical models, we obtained position-velocity (PV) diagrams in the [N II]$\\lambda$6583 line for comparison with the observations. We find that the spectral characteristics of M 1-32 and M 3-15 can be explained with the same physical model -a jet moving inside an AGB wind- using different parameters (physical conditions and position angles of the jet). In agreement with our model and observa...

  18. WSO-UV project

    Science.gov (United States)

    Sachkov, Mikhail; Shustov, Boris; Gómez de Castro, Ana Ines

    2014-03-01

    During last three decades, astronomers have enjoyed continuous access to the 100-300 nm ultraviolet (UV) spectral range where the resonance transitions of the most abundant atoms and ions (at temperatures between 3000 and 300 000 K) reside. This UV range is not accessible from ground-based facilities. The successful International Ultraviolet Explorer (IUE) observatory, the Russian ASTRON mission and successor instruments such as the Galaxy Evolution Explorer (GALEX) mission or the COS and STIS spectrographs on-board the Hubble Space Telescope (HST) prove the major impact of observations in the UV wavelength range in modern astronomy. Future access to space-based observatories is expected to be very limited. For the next decade, the post-HST era, the World Space Observatory - Ultraviolet (WSO-UV) will be the only 2-m class UV telescope with capabilities similar to the HST. WSO-UV will be equipped with instruments for imaging and spectroscopy and it will be a facility dedicated, full-time, to UV astronomy. In this article, we briefly outline the current status of the WSO-UV mission and the science management plan.

  19. The World Space Observatory–UV Project as a Tool for Exoplanet Science

    Science.gov (United States)

    Shustov, Boris M.; Sachkov, Mikhail E.; Bisikalo, Dmitry V.; de Castro, Ana-Ines Gómez

    During last three decades, astronomers have had practically continuous access to the 100-300 nm spectral range that is unreachable with ground-based instruments but where astrophysical processes can be efficiently studied with unprecedented capability. The successful International Ultraviolet Explorer (IUE) observatory, Russian ASTRON mission and successor instruments such as the COS and STIS spectrographs on-board the Hubble Space Telescope (HST) demonstrate the major impact that observations in the UV wavelength range have had on modern astronomy. Many exoplanetary studies have been performed in the UV domain, both Far-UV and Near-UV. This spectral region contains many resonance lines of common elements, including Ly α, which provided a unique possibility to study physical and chemical properties of planetary atmospheres. Future access to space-based observatories is expected to be very limited. For the next decade, the post-HST era, the World Space Observatory UltraViolet (WSO-UV) will be the only large telescope class mission for UV observations, both spectroscopic and imaging. In its potential, the WSO-UV mission is similar to the HST, but all the observing time will be available for UV astronomy. In this chapter, we briefly outline the WSO-UV mission model, instrumentation description, science management plan as well as some of the key science issues that WSO-UV will address during its lifetime. This information should help exoplanet researchers to start to prepare their future observations with WSO-UV.

  20. Interplay of tidal evolution and stellar wind braking in the rotation of stars hosting massive close-in planets

    CERN Document Server

    Ferraz-Mello, S; Folonier, H; Csizmadia, Sz; Nascimento, J -D do; Pätzold, M

    2015-01-01

    This paper deals with the application of the creep tide theory (Ferraz-Mello, Cel. Mech. Dyn. Astron. vol. 116, 109, 2013) to the study of the rotation of stars hosting massive close-in planets. The stars have nearly the same tidal relaxation factors as gaseous planets and the evolution of their rotation is similar to that of close-in hot Jupiters: they tidally evolve towards a stationary solution. However, stellar rotation may also be affected by stellar wind braking. Thus, while the rotation of a quiet host star evolves towards a stationary attractor with a frequency ($1+6e^2$) times the orbital mean-motion of the companion, the continuous loss of angular momentum in an active star displaces the stationary solution towards slower values: Active host stars with big close-in companions tend to have rotational periods larger than the orbital periods of their companions. The study of some hypothetical examples shows that because of tidal evolution, the rules of gyrochronology cannot be used to estimate the age ...

  1. Observations and 3D Hydrodynamical models of planetary nebulae with Wolf Rayet type central stars

    Science.gov (United States)

    Rechy-García, J. S.; Velázquez, P. F.; Peña, M.; Raga, A. C.

    2016-10-01

    We present high-resolution, long-slit spectroscopic observations of two planetary nebulae with [WC] central stars located near the galactic bulge, M 1-32 and M 3-15. The observations were obtained with the 2.1-m telescope at the Observatorio Astronómico Nacional, San Pedro Mártir. M 1-32 shows wide wings on the base of its emission lines and M 3-15 has two very faint high-velocity knots. In order to model both PNe we built a three-dimensional model consisting of a jet interacting with an equatorially concentrated slow wind, emulating the presence of a dense torus, using the Yguazú hydrodynamical code. From our hydrodynamical models, we obtained position-velocity (PV) diagrams in the [N II]λ6583 line for comparison with the observations. We find that the spectral characteristics of M 1-32 and M 3-15 can be explained with the same physical model -a jet moving inside an AGB wind- using different parameters (physical conditions and position angles of the jet). In agreement with our model and observations, these objects contain a dense torus seeing pole-on and a bipolar jet escaping thorough the poles. Then we propose to classify this kind of objects as spectroscopic bipolar nebulae, although they have been classified morphologically as compact, round, or elliptical nebulae or with "close collimated lobes".

  2. Exploración del catálogo de objetos en emisión H de Henize y All Sky Automated Survey: nuevas variables y tipos espectrales

    Science.gov (United States)

    Jaque Arancibia, M.; Barbá, R. H.; Collado, A.; Gamen, R.; Arias, J. I.

    2016-08-01

    Large astronomical surveys allow us to do systematic studies of stellar populations with significant statistical weight. In this study, we have cross-correlated the Henize's (1976) catalog of stellar sources with H emission-line with “The All Sky Automated Survey'' database. After the positional cross-matching we have found that 1402 of 1926 H sources have ASAS light-curves. From that number, more than 50 (723 sources) are periodic variables with amplitude larger than 0.05 magnitudes, while 276 sources show photometric variations without a clear periodicity. Variable stars that we have found are of many different types, among them Miras, eclipsing binaries, bursting stars, etc. Also, only 133 stars are known previously as variable sources in ASAS catalogue, and 93 of them were studied previously in detail. In order to characterize the nature of the sources, we have started a medium-resolution spectroscopic survey of the unstudied variable emission-line objects using the 2.15-m Jorge Sahade Telescope at Complejo Astronómico El Leoncito (Argentina). At the moment, we have observed a set of 67 blue stars selected using 2MASS colors, being almost all of them Be-type stars. This set of bright new variable Be-type stars is ideal for follow-up monitoring for the study of the Be-phenomenon.

  3. Telescope Fabra ROA Montsec: a new robotic wide-field Baker-Nunn facility

    CERN Document Server

    Fors, O; Muiños, J L; Montojo, F J; Baena-Gallé, R; Boloix, J; Morcillo, R; Merino, M T; Downey, E C; Mazur, M J

    2012-01-01

    A Baker-Nunn Camera (BNC), originally installed at the Real Instituto y Observatorio de la Armada (ROA) in 1958, was refurbished and robotized. The new facility, called Telescope Fabra ROA Montsec (TFRM), was installed at the Observatori Astron\\`omic del Montsec (OAdM). The process of refurbishment is described in detail. Most of the steps of the refurbishment project were accomplished by purchasing commercial components, which involve little posterior engineering assembling work. The TFRM is a 0.5m aperture f/0.96 optically modified BNC, which offers a unique combination of instrumental specifications: fully robotic and remote operation, wide-field of view (4.4 deg x 4.4 deg), moderate limiting magnitude (V~19.5mag), ability of tracking at arbitrary right ascension and declination rates, as well as opening and closing CCD shutter at will during an exposure. Nearly all kind of image survey programs can benefit from those specifications. Apart from other less time consuming programs, since the beginning of sci...

  4. Monitoring Light Pollution on the Starlight Reserve of Montsec

    Science.gov (United States)

    Ribas, S. J.; Paricio, S.; Canal-Domingo, R.; Gustems, L.; Calvo, C. O.

    2015-05-01

    Montsec Mountains are a special protected place in Catalonia (NE of Iberian Peninsula). Since 2013 the site has been declared Starlight Reserve and Touristic Destination. In the last three years different projects took place in Montsec to evaluate the quality of night sky and the effects of Light Pollution of nearby (and not so nearby) municipalities. Using SQM techniques in RoadRunner configuration (installed on a car) we have evaluated all the region (1 600 km^2) and we determined the distribution of night sky brightness detecting some excellent areas with values around 21.5--22.0 mags. In addition we have evaluated the effects of the closest big city (Lleida with around 200 000 inhabitants) and we have estimated long distance effects of this city on the natural sky. The effect is detected on zenith up to 25 km away from the city. These data show the critical problem of the long-distance effects of LP on protected areas. To complete the monitoring of the region, a new SQM network is ongoing in cooperation with Parc Astronòmic Montsec and Catalan Service against Light Pollution. During 2014 six SQM permanent detectors are starting their measurements around the area of Montsec and major cities that affects this protected area. This data could be combined with meteorological data (clouds, humidity, etc) in some of the evaluation sites.

  5. Velocidades radiales en Collinder 121

    Science.gov (United States)

    Arnal, M.; Morrell, N.

    Se han llevado a cabo observaciones espectroscópicas de unas treinta estrellas que son posibles miembros del cúmulo abierto Collinder 121. Las mismas fueron realizadas con el telescopio de 2.15m del Complejo Astronómico El Leoncito (CASLEO). El análisis de las velocidades radiales derivadas del material obtenido, confirma la realidad de Collinder 121, al menos desde el punto de vista cinemático. La velocidad radial baricentral (LSR) del cúmulo es de +17 ± 3 km.s-1. Esta velocidad coincide, dentro de los errores, con la velocidad radial (LSR) de la nebulosa anillo S308, la cual es de ~20 ± 10 km.s-1. Como S308 se encuentra físicamente asociada a la estrella Wolf-Rayet HD~50896, es muy probable que esta última sea un miembro de Collinder 121. Desde un punto de vista cinemático, la supergigante roja HD~50877 (K3Iab) también pertenecería a Collinder 121. Basándonos en la pertenencia de HD~50896 a Collinder 121, y en la interacción encontrada entre el viento de esta estrella y el medio interestelar circundante a la misma, se estima para este cúmulo una distancia del orden de 1 kpc.

  6. L^1 -optimality conditions for the circular restricted three-body problem

    Science.gov (United States)

    Chen, Zheng

    2016-06-01

    In this paper, the L^1 -minimization for the translational motion of a spacecraft in the circular restricted three-body problem (CRTBP) is considered. Necessary conditions are derived by using the Pontryagin Maximum Principle (PMP), revealing the existence of bang-bang and singular controls. Singular extremals are analyzed, recalling the existence of the Fuller phenomenon according to the theories developed in (Marchal in J Optim Theory Appl 11(5):441-486, 1973; Zelikin and Borisov in Theory of Chattering Control with Applications to Astronautics, Robotics, Economics, and Engineering. Birkhäuser, Basal 1994; in J Math Sci 114(3):1227-1344, 2003). The sufficient optimality conditions for the L^1 -minimization problem with fixed endpoints have been developed in (Chen et al. in SIAM J Control Optim 54(3):1245-1265, 2016). In the current paper, we establish second-order conditions for optimal control problems with more general final conditions defined by a smooth submanifold target. In addition, the numerical implementation to check these optimality conditions is given. Finally, approximating the Earth-Moon-Spacecraft system by the CRTBP, an L^1 -minimization trajectory for the translational motion of a spacecraft is computed by combining a shooting method with a continuation method in (Caillau et al. in Celest Mech Dyn Astron 114:137-150, 2012; Caillau and Daoud in SIAM J Control Optim 50(6):3178-3202, 2012). The local optimality of the computed trajectory is asserted thanks to the second-order optimality conditions developed.

  7. A new class of solutions of anisotropic charged distributions on pseudo-spheroidal spacetime

    Science.gov (United States)

    Ratanpal, B. S.; Thomas, V. O.; Pandya, D. M.

    2015-12-01

    In the present article a new class of exact solutions of Einstein's field equations for charged anisotropic distribution is obtained on the background of pseudo-spheroidal spacetime characterized by the metric potential g_{rr}=1+K {r2/R2}/{1+r2/R2}, where K and R are geometric parameters of the spacetime. The radial pressure pr and electric field intensity E are taken in the form 8π pr=K-1/R2 (1-{r2/R2)}/{ (1+Kr2/R2 )2} and E2=α(K-1){r2/R2}/{R2 (1+Kr2/R2 )2}. The bounds of geometric parameter K and the parameter α appearing in the expression of E2 are obtained by imposing the requirements for a physically acceptable model. It is found that the model is in good agreement with the observational data of number of compact stars like 4U 1820-30, PSR J1903+327, 4U 1608-52, Vela X-1, PSR J1614-2230, Cen X-3 given by Gangopadhyay et al. (Mon. Not. R. Astron. Soc. 431:3216, 2013). When α= 0, the model reduces to the uncharged anisotropic distribution given by Ratanpal et al. (arXiv:1506.08512 [gr-qc], 2015).

  8. Sensitivity to a possible variation of the Proton-to-Electron Mass Ratio of Torsion-Wagging-Rotation Transitions in Methylamine (CH3NH2)

    CERN Document Server

    Ilyushin, Vadim V; Kozlov, Mikhail G; Levshakov, Sergei A; Kleiner, Isabelle; Ubachs, Wim; Bethlem, Hendrick L

    2012-01-01

    We determine the sensitivity to a possible variation of the proton-to-electron mass ratio \\mu for torsion-wagging-rotation transitions in the ground state of methylamine (CH3NH2). Our calculation uses an effective Hamiltonian based on a high-barrier tunneling formalism combined with extended-group ideas. The \\mu-dependence of the molecular parameters that are used in this model are derived and the most important ones of these are validated using the spectroscopic data of different isotopologues of methylamine. We find a significant enhancement of the sensitivity coefficients due to energy cancellations between internal rotational, overall rotational and inversion energy splittings. The sensitivity coefficients of the different transitions range from -19 to +24. The sensitivity coefficients of the 78.135, 79.008, and 89.956 GHz transitions that were recently observed in the disk of a z = 0.89 spiral galaxy located in front of the quasar PKS 1830-211 [S. Muller et al. Astron. Astrophys. 535, A103 (2011)] were c...

  9. Site testing for submillimetre astronomy at Dome C, Antarctica

    CERN Document Server

    Tremblin, P; Schneider, N; Durand, G Al; Ashley, M C B; Lawrence, J S; Luong-Van, D M; Storey, J W V; Durand, G An; Reinert, Y; Veyssiere, C; Walter, C; Ade, P; Calisse, P G; Challita, Z; Fossat, E; Sabbatini, L; Pellegrini, A; Ricaud, P; Urban, J

    2011-01-01

    Over the past few years a major effort has been put into the exploration of potential sites for the deployment of submillimetre astronomical facilities. Amongst the most important sites are Dome C and Dome A on the Antarctic Plateau, and the Chajnantor area in Chile. In this context, we report on measurements of the sky opacity at 200 um over a period of three years at the French-Italian station, Concordia, at Dome C, Antarctica. We also present some solutions to the challenges of operating in the harsh polar environ- ment. Dome C offers exceptional conditions in terms of absolute atmospheric transmission and stability for submillimetre astron- omy. Over the austral winter the PWV exhibits long periods during which it is stable and at a very low level (0.1 to 0.3 mm). Higher values (0.2 to 0.8 mm) of PWV are observed during the short summer period. Based on observations over three years, a transmission of around 50% at 350 um is achieved for 75% of the time. The 200-um window opens with a typical transmission...

  10. A new look at photometry of the Moon

    Science.gov (United States)

    Goguen, J.D.; Stone, T.C.; Kieffer, H.H.; Buratti, B.J.

    2010-01-01

    We use ROLO photometry (Kieffer, H.H., Stone, T.C. [2005]. Astron. J. 129, 2887-2901) to characterize the before and after full Moon radiance variation for a typical highlands site and a typical mare site. Focusing on the phase angle range 45??. ) to calculate the scattering matrix and solve the radiative transfer equation for I/. F. The mean single scattering albedo is ??=0.808, the asymmetry parameter is ???cos. ?????=0.77 and the phase function is very strongly peaked in both the forward and backward scattering directions. The fit to the observations for the highland site is excellent and multiply scattered photons contribute 80% of I/. F. We conclude that either model, roughness or multiple scattering, can match the observations, but that the strongly anisotropic phase functions of realistic particles require rigorous calculation of many orders of scattering or spurious photometric roughness estimates are guaranteed. Our multiple scattering calculation is the first to combine: (1) a regolith model matched to the measured particle size distribution and index of refraction of the lunar soil, (2) a rigorous calculation of the particle phase function and solution of the radiative transfer equation, and (3) application to lunar photometry with absolute radiance calibration. ?? 2010 Elsevier Inc.

  11. Simulación de la trayectoria de un cohete de dos etapas para posicionamiento de un nanosatélite en órbita

    Directory of Open Access Journals (Sweden)

    Jhonathan Orlando Murcia Piñeros

    2014-01-01

    Full Text Available En el presente artículo se estudia el posible lanzamiento de un cohete de dos etapas impulsado por propelentes líquidos tipo RP-1 para transportar una carga útil de 4 kg equivalente a la masa de un nano-satélite de tres unidades de Cubesat. Se plantea el estudio con el diseño conceptual del cohete portador implementando un código computacional de optimización con la finalidad de reducir la masa al despegue y aumentar la velocidad. Se eligió como sitio de lanzamiento desde Colombia a la base del Grupo Aéreo del Oriente (GAORI en Marandúa, Vichada, dado que en la actualidad se realizan investigaciones en lanzamiento de cohetes y ha sido utilizado por universidades para el desarrollo de tales investigaciones. Los valores obtenidos anteriormente son introducidos en un código computacional en FORTRAN desarrollado en el Observatorio Astronómico de la Universidad Nacional de Colombia para obtener el comportamiento de la trayectoria de vuelo del cohete durante su fase de ascenso e inyección orbital.

  12. Search for Rapid Changes in the Visible-Light Corona during the 21 June 2001 Total Solar Eclipse

    CERN Document Server

    Rudawy, P; Buczylko, A; Williams, D R; Keenan, F P

    2010-01-01

    Some 8000 images obtained with the SECIS fast-frame CCD camera instrument located at Lusaka, Zambia, during the total eclipse of 21 June 2001 have been analyzed to search for short-period oscillations in intensity that could be a signature of solar coronal heating mechanisms by MHD wave dissipation. Images were taken in white- light and Fe XIV green-line (5303 A) channels over 205 seconds (frame rate 39 s-1), approximately the length of eclipse totality at this location, with a pixel size of four arcseconds square. The data are of considerably better quality than were obtained during the 11 August 1999 total eclipse, observed by us (Rudawy et al.: Astron. Astrophys. 416, 1179, 2004), in that the images are much better exposed and enhancements in the drive system of the heliostat used gave a much improved image stability. Classical Fourier and wavelet techniques have been used to analyze the emission at 29518 locations, of which 10714 had emission at reasonably high levels, searching for periodic fluctuations ...

  13. OBSERVATION OF SPACE DEBRIS IN TARIJA’S OBSERVATORY, BOLIVIA IN THE FRAME OF THE PROGRAM ISON (INTERNATIONAL SCIENTIFIC OPTICAL NETWORK

    Directory of Open Access Journals (Sweden)

    R. Zalles Barrera

    2014-01-01

    Full Text Available El Observatorio Astron ́mico Nacional de Tarija, Bolivia con los telescopios que cuenta y en cooperaci ́n con o o la Red Internacional (ISON en septiembre y octubre de 2005 llevaron a cabo observaciones experimentales de detecci ́n de basura espacial en la ́rbita m ́s poblada, la geoestacionaria, debido al mayor n ́mero de sat ́lites o o a u e que se han puesto en ́rbita. A partir de octubre de 2006 se realizan observaciones regulares con el Astr ́grafo o o de 23 cm y c ́mara CCD; posteriormente se instal ́ un nuevo y especial telescopio para este fin, el Sigma Ori 25. a o A la fecha se est ́n realizando trabajos en mejoras de la parte mec ́nica y ́ptica adem ́s de la automatizaci ́n a a o a o o del Zeiss 600 para incluirlo en este programa de observación.

  14. Mercury's resonant rotation from secular orbital elements

    Science.gov (United States)

    Stark, Alexander; Oberst, Jürgen; Hussmann, Hauke

    2015-11-01

    We used recently produced Solar System ephemerides, which incorporate 2 years of ranging observations to the MESSENGER spacecraft, to extract the secular orbital elements for Mercury and associated uncertainties. As Mercury is in a stable 3:2 spin-orbit resonance, these values constitute an important reference for the planet's measured rotational parameters, which in turn strongly bear on physical interpretation of Mercury's interior structure. In particular, we derive a mean orbital period of (87.96934962 ± 0.00000037) days and (assuming a perfect resonance) a spin rate of (6.138506839± 0.000000028)°/day. The difference between this rotation rate and the currently adopted rotation rate (Archinal et al. in Celest Mech Dyn Astron 109(2):101-135, 2011. doi:10.1007/s10569-010-9320-4), corresponds to a longitudinal displacement of approx. 67 m per year at the equator. Moreover, we present a basic approach for the calculation of the orientation of the instantaneous Laplace and Cassini planes of Mercury. The analysis allows us to assess the uncertainties in physical parameters of the planet, when derived from observations of Mercury's rotation.

  15. Determination of Reddening and Age for Ten Large Magellanic Cloud Star Clusters from Integrated Spectroscopy

    Science.gov (United States)

    Ahumada, Andrea V.; Vega, Luis R.; Clariá, Juan J.; Oddone, Mónica A.; Palma, Tali

    2016-09-01

    We present flux-calibrated integrated spectra in the optical range (3700-6800 Å) obtained at Complejo Astronómico El Leoncito (CASLEO, Argentina) for a sample of 10 concentrated star clusters belonging to the Large Magellanic Cloud (LMC). No previous data exist for two of these objects (SL 142 and SL 624), while most of the remaining clusters have been only poorly studied. We derive simultaneously foreground E(B - V) reddening values and ages for the cluster sample by comparing their integrated spectra with template LMC cluster spectra and with two different sets of simple stellar population models. Cluster reddening values and ages are also derived from both available interstellar extinction maps and by using diagnostic diagrams involving the sum of equivalent widths of some selected spectral features and their calibrations with age, respectively. For the studied sample, we derive ages between 1 Myr and 240 Myr. In an effort to create a spectral library at the LMC metallicity level with several clusters per age range, the cluster sample presented here stands out as a useful complement to previous ones.

  16. Interstellar scintillations of PSR B1919+21: space-ground interferometry

    CERN Document Server

    Shishov, V I; Gwinn, C R; Andrianov, A S; Popov, M V; Rudnitskiy, A G; Soglasnov, V A

    2016-01-01

    We carried out observations of pulsar PSR B1919+21 at 324 MHz to study the distribution of interstellar plasma in the direction of this pulsar. We used the RadioAstron (RA) space radiotelescope together with two ground telescopes: Westerbork (WB) and Green Bank (GB). The maximum baseline projection for the space-ground interferometer was 60000 km. We show that interstellar scintillation of this pulsar consists of two components: diffractive scintillations from inhomogeneities in a layer of turbulent plasma at a distance $z_{1} = 440$ pc from the observer; and weak scintillations from a screen located near the observer at $z_{2} = 0.13$ pc. Furthermore, in the direction to the pulsar we detected a prism that deflects radiation, leading to a shift of observed source position. We show that the influence of the ionosphere can be ignored for the space-ground baseline. Analysis of the spatial coherence function for the space-ground baseline (RA-GB) yielded the scattering angle in the observer plane: $\\theta_{scat}$...

  17. A GEOMETRICAL MODEL FOR THE CATALOGS OF GALAXIES

    Directory of Open Access Journals (Sweden)

    L. Zaninetti

    2010-01-01

    Full Text Available La red 3D que se origina por las caras de los polihedros irregulares poissonianos de Voronoi podr a representar la estructura b sica para la formaci n de galaxias. En consecuencia, la apariencia espacial de los cat logos de galaxias podr a reproducirse. Los cat logos seleccionados para la simulaci n fueron el 2dF Galaxy Redshift Survey y el Third Reference Catalog of Bright Galaxies. Para explicar el n mero observado de galaxias con un ujo (o magnitud dado como funci n del corrimiento al rojo deben examinarse cuidadosamente las propiedades fotom tricas de las galaxias, tanto desde un punto de vista astron mico como te rico. La estad stica del volumen de Voronoi normalizado se modela por dos distribuciones, y el super-hueco en Eridanus se identi ca como el mayor volumen perteneciente al polihedro de Voronoi. El comportamiento de la funci n de correlaci n de las galaxias se simula adoptando el esquema de caras gruesas de polihedros de Voronoi para escalas peque as, y conservando los argumentos usuales para escalas grandes.

  18. Suzaku observations of the hard X-ray spectrum of Vela Jr. (SNR RX J0852.0-4622)

    Science.gov (United States)

    Takeda, Sawako; Bamba, Aya; Terada, Yukikatsu; Tashiro, Makoto S.; Katsuda, Satoru; Yamazaki, Ryo; Ohira, Yutaka; Iwakiri, Wataru

    2016-06-01

    We report the results of Suzaku observations of the young supernova remnant, Vela Jr. (RX J0852.0-4622), which is known to emit synchrotron X-rays, as well as TeV gamma-rays. Utilizing 39 Suzaku mapping observation data from Vela Jr., a significant hard X-ray emission is detected with the hard X-ray detector (HXD) from the northwest TeV-emitting region. The X-ray spectrum is reproduced well by a single power-law model with a photon index of 3.15^{+1.18}_{-1.14} in the 12-22 keV band. Compiling this hard X-ray spectrum with the soft X-ray spectrum simultaneously observed with the X-ray imaging spectrometer (XIS) onboard Suzaku, we find that the wide-band X-ray spectrum in the 2-22 keV band is reproduced with a single power-law or concave broken power-law model, which are statistically consistent with each other. Whichever of the two models, single or broken power-law, is appropriate, clearly the spectrum has no roll-off structure. Applying this result to the method introduced in Yamazaki et al. (2014, Res. Astron. Astrophys., 14, 165), we find that a one-zone synchrotron model with electron spectrum having a power-law plus exponential cut-off may not be applicable to Vela Jr.

  19. Impactos ambientais e sociais da Copa do Mundo de 2014

    Directory of Open Access Journals (Sweden)

    Marilia Carla de Mello Gaia

    2014-05-01

    Full Text Available Desde a escolha do Brasil, em 2007, para sediar a Copa do Mundo de Futebol de 2014 e as Olimpíadas de 2016, este é um tema recorrente na mídia e em demais espaços de socialização dos brasileiros. Muitas discussões a cerca destes megaeventos esportivos envolvem os benefícios relacionados ao incentivo ao esporte nacional, ao incremento no turismo e na economia e às obras de infraestrutura (sistema de transporte urbano, aeroportos, arenas esportivas, comércio, etc.. A partir das manifestações populares em junho de 2013, principalmente, amplia-se em uma parcela da população brasileira um outro olhar sobre estes eventos esportivos, sobretudo os questionamentos relacionados às necessidades sociais da população em detrimento dos astronômicos investimentos financeiros e políticos para a Copa. Neste contexto, este artigo se destina a discutir alguns elementos envolvidos nos impactos sociais e ambientais da realização da Copa do Mundo de Futebol e das Olimpíadas no Brasil.

  20. Impactos ambientais e sociais da Copa do Mundo de 2014 http://dx.doi.org/10.15601/1983-7631/rt.v7n12p59-66

    Directory of Open Access Journals (Sweden)

    Marilia Carla de Mello Gaia

    2014-05-01

    Full Text Available Desde a escolha do Brasil, em 2007, para sediar a Copa do Mundo de Futebol de 2014 e as Olimpíadas de 2016, este é um tema recorrente na mídia e em demais espaços de socialização dos brasileiros. Muitas discussões a cerca destes megaeventos esportivos envolvem os benefícios relacionados ao incentivo ao esporte nacional, ao incremento no turismo e na economia e às obras de infraestrutura (sistema de transporte urbano, aeroportos, arenas esportivas, comércio, etc.. A partir das manifestações populares em junho de 2013, principalmente, amplia-se em uma parcela da população brasileira um outro olhar sobre estes eventos esportivos, sobretudo os questionamentos relacionados às necessidades sociais da população em detrimento dos astronômicos investimentos financeiros e políticos para a Copa. Neste contexto, este artigo se destina a discutir alguns elementos envolvidos nos impactos sociais e ambientais da realização da Copa do Mundo de Futebol e das Olimpíadas no Brasil.

  1. Improved Determination of the Location of the Temperature Maximum in the Corona

    Science.gov (United States)

    Lemaire, J. F.; Stegen, K.

    2016-10-01

    The most used method to calculate the coronal electron temperature [ Te (r)] from a coronal density distribution [ ne (r)] is the scale-height method (SHM). We introduce a novel method that is a generalization of a method introduced by Alfvén (Ark. Mat. Astron. Fys. 27, 1, 1941) to calculate Te(r) for a corona in hydrostatic equilibrium: the "HST" method. All of the methods discussed here require given electron-density distributions [ ne (r)] which can be derived from white-light (WL) eclipse observations. The new "DYN" method determines the unique solution of Te(r) for which Te(r → ∞) → 0 when the solar corona expands radially as realized in hydrodynamical solar-wind models. The applications of the SHM method and DYN method give comparable distributions for Te(r). Both have a maximum [ T_{max}] whose value ranges between 1 - 3 MK. However, the peak of temperature is located at a different altitude in both cases. Close to the Sun where the expansion velocity is subsonic ( r corona when the electron-density distribution is obtained from WL coronal observations.

  2. The gas production of Comet 9P/Tempel 1 around the Deep Impact date

    Science.gov (United States)

    Weiler, M.; Rauer, H.; Knollenberg, J.; Sterken, C.

    2007-10-01

    The target of the Deep Impact space mission (NASA), Comet 9P/Tempel 1, was observed from two nights before impact to eight nights after impact using the FORS spectrographs at the ESO VLT UT1 and UT2 telescopes. Low resolution optical long-slit spectra were obtained to study the evolution of the gas coma around the Deep Impact event. Following first results of this observing campaign on the CN and dust activity [Rauer, H., Weiler, M., Sterken, C., Jehin, E., Knollenberg, J., Hainaut, O., 2006. Astron. Astrophys. 459, 257-263], this work presents a study of the complete dataset on CN, C 2, C 3, and NH 2 activity of Comet 9P/Tempel 1. An extended impact gas cloud was observed moving radially outwards. No compositional differences between this impact cloud and the undisturbed coma were found as far as the observed radicals are concerned. The gas production rates before and well after impact indicate no change in the cometary activity on an intermediate time scale. Over the observing period, the activity of Comet 9P/Tempel 1 was found to be related to the rotation of the cometary nucleus. The rotational lightcurve for different gaseous species provides indications for compositional differences among different parts of the nucleus surface.

  3. SPECKLE INTERFEROMETRY AT THE OBSERVATORIO ASTRONÓMICO NACIONAL. VI.

    Directory of Open Access Journals (Sweden)

    V. G. Orlov

    2015-01-01

    Full Text Available Presentamos mediciones de estrellas dobles mediante interferometría de motas, obtenidas en agosto de 2010 con el telescopio de 1.5 m y en mayo de 2010 con el telescopio de 2.1 m del Observatorio Astronómico Nacional en SPM (México. Reportamos los resultados de 331 mediciones de 321 sistemas, con una magnitud límite para las primarias de V = 12.9. Las separaciones angulares medidas están comprendidas entre 0.13 y 7.39 segundos de arco. 269 pares resultaron tener separaciones de menos de 1 segundo de arco. El error medio en las separaciones es de 0.032 segundos de arco, y en los ángulos de posición, 2 grados. La ambigüedad usual de 180 grados en los ángulos de posición fue corregida para la mayoría de ellos usando observaciones de otros autores.

  4. LOFAR-UK White Paper: A Science case for UK involvement in LOFAR

    CERN Document Server

    Best, P N

    2008-01-01

    LOFAR, the Low-Frequency Array, is a next-generation software-driven radio telescope operating between 30 and 240MHz, currently under construction by ASTRON in the Netherlands. This low frequency radio band is one of the few largely unexplored regions of the electromagnetic spectrum. The sensitivity and angular resolution offered by LOFAR will be two to three orders of magnitude better than existing telescopes, and as such it will open up this new window on the Universe. LOFAR will impact on a broad range of astrophysics, from cosmology to solar system studies. There is growing European involvement in LOFAR, driven by the need to add stations far from the main core in order to improve angular resolution. LOFAR-UK is a project aimed at cementing UK participation in LOFAR via the operation of four stations within the UK. LOFAR-UK ground stations will allow LOFAR observations to reach sub-arcsecond scales at the highest frequencies, and as a result will also improve the (confusion-limited) sensitivity limit of t...

  5. Dynamics of the Jupiter Trojans with Saturn's perturbation when the two planets are in migration

    Science.gov (United States)

    Hou, Xiyun; Scheeres, Daniel J.; Liu, L.

    2016-08-01

    In a previous paper (Hou et al. in Celest Mech Dyn Astron 119:119-142, 2014a), the problem of dynamical symmetry between two Jupiter triangular libration points (TLPs) with Saturn's perturbation in the present configuration of the two planets was studied. A small short-time scale spatial asymmetry exists but gradually disappears with the time going, so the planar stable regions around the two Jupiter TLPs should be dynamically symmetric from a longtime perspective. In this paper, the symmetry problem is studied when the two planets are in migration. Several mechanisms that can cause asymmetries are discussed. Studies show that three important ones are the large short-time scale spatial asymmetry when Jupiter and Saturn are in resonance, the changing orbits of Jupiter and Saturn in the planet migration process, and the chaotic nature of Trojan orbits during the planet migration process. Their joint effects can cause an observable difference to the two Jupiter Trojan swarms. The thermal Yarkovsky effect is also found to be able to cause dynamical differences to the two TLPs, but generally they are too small to be practically observed.

  6. Telescope Fabra ROA Montsec: A New Robotic Wide Field Baker-Nunn Facility

    Science.gov (United States)

    Fors, Octavi; Núñez, Jorge; Muiños, José Luis; Montojo, Francisco Javier; Baena-Gallé, Roberto; Boloix, Jaime; Morcillo, Ricardo; Merino, María Teresa; Downey, Elwood C.; Mazur, Michael J.

    2013-05-01

    A Baker-Nunn Camera (BNC), originally installed at the Real Instituto y Observatorio de la Armada (ROA) in 1958, was refurbished and robotized. The new facility, called Telescope Fabra ROA Montsec (TFRM), was installed at the Observatori Astronòmic del Montsec (OAdM). The process of refurbishment is described in detail. Most of the steps of the refurbishment project were accomplished by purchasing commercial components, which involve little posterior engineering assembling work. The TFRM is a 0.5 m aperture f/0.96 optically modified BNC, which offers a unique combination of instrumental specifications: fully robotic and remote operation, wide field of view (4°.4 × 4°.4), moderate limiting magnitude (V ~ 19.5 mag), ability of tracking at arbitrary right ascension (α) and declination (δ) rates, as well as opening and closing CCD shutter at will during an exposure. Nearly all kinds of image survey programs can benefit from those specifications. Apart from other less time-consuming programs, since the beginning of science TFRM operations we have been conducting two specific and distinct surveys: super-Earths transiting around M-type dwarfs stars, and geostationary debris in the context of Space Situational Awareness/Space Surveillance and Tracking (SSA/SST) programs. Preliminary results for both cases will be shown.

  7. THE SAN PEDRO MÁRTIR PLANETARY NEBULA KINEMATIC CATALOGUE: EXTRAGALACTIC PLANETARY NEBULAE

    Directory of Open Access Journals (Sweden)

    M. G. Richer

    2010-01-01

    Full Text Available Presentamos datos cinemáticos para 211 nebulosas planetarias brillantes en once galaxias del Grupo Local: M31 (137 NPs, M32 (13, M33 (33, Fornax (1,Sagittarius (3, NGC 147 (2, NGC 185 (5, NGC 205 (9, NGC 6822 (6, Leo A (1, y Sextans A (1. Adquirimos los datos en el Observatorio Astronómico Nacional en la Sierra de San Pedro Mártir con el telescopio de 2.1 m y el espectrómetro Manchester Echelle en la línea de [O III]l 5007 con una resolución de 11 km s¿1. Observamos algunos objetos en H¿. La cinemática de nebulosas planetarias brillantes no depende fuertemente de la metalicidad o la edad de la población estelar progenitora en sus galaxias huéspedes, aunque existen pequeñas diferencias sistemáticas. La cinemática y la luminosidad en Hb de las cáscaras nebulares requieren la aceleraci ón de las cáscaras durante la evolución temprana de las estrellas centrales. Así, la cinemática representa otro argumento a favor de estrellas progenitoras similares para las nebulosas planetarias brillantes en todas galaxias.

  8. Time transfer by laser link (T2L2): characterization and calibration of the flight instrument

    Science.gov (United States)

    Samain, E.; Vrancken, P.; Guillemot, P.; Fridelance, P.; Exertier, P.

    2014-10-01

    The T2L2 project (time transfer by laser link) allows for the synchronization of remote ultra-stable clocks over intercontinental distances (Fridelance et al 1997 Exp. Astron. 7, Samain and Fridelance 1998 Metrologia 35 151-9). The principle is derived from satellite laser ranging technology with dedicated space equipment designed to record arrival times of laser pulses at the satellite. The space segment has been launched in June 2008 as a passenger experiment on the ocean altimetry satellite Jason 2. T2L2 had been specified to yield a time stability of better than 1 ps over 1000 s integration time and an accuracy of better than 100 ps. This level of performance requires a rigorous data processing which can be performed only with a comprehensive calibration model of the whole instrumentation. For this purpose, several experimental measurements have been performed before and during the integration phase of the T2L2 space instrument. This instrument model is one of the cornerstones of the data reduction process which is carried out to translate the raw information to a usable picosecond time transfer. After providing a global synopsis of the T2L2 space instrument, the paper gives a description of the experimental setup for the instrument characterization. It then details the different contributions within the calibration model and concludes with an applied example of a space to ground time transfer.

  9. Development of the control system for the 40m OAN radiotelescope with the Alma Common Software

    Science.gov (United States)

    de Vicente, P.; Bolaño, R.; Barbas, L.

    2006-07-01

    The Observatorio Astronómico Nacional (OAN) is building a 40m radiotelescope in its facilities in Yebes (Spain) which will be delivered in summer 2006. The radiotelescope is an instrument composed of antenna, receivers, backends, and auxiliary equipment connected through a Local Area Network (LAN). The control system has to deal with a distributed environment which needs to be remotely controlled and monitored from external heterogeneous users (astronomers and engineers) and requires multiple processes simultaneously working and being synchronized. We have chosen the Alma Common Software (ACS) framework for the development of the control system. ACS provides an implementation of the component/container paradigm via Common Object Request Broker Architecture (CORBA) and also provides general purpose utility libraries, hiding the complexity of CORBA to the developer. ACS is supported by the European Southern Observatory (ESO) and the National Radioastronomy Observatory (NRAO) for the Atacama Large Millimeter Array (ALMA) with a lifetime similar to our radiotelescope. This is an important guarantee for the OAN with a very reduced software team. We present an overview of the planned software architecture of the radiotelescope and the current status of the development of the components.

  10. Dark energy stars: Stable configurations

    CERN Document Server

    Bhar, Piyali; Rahaman, Farook; Banerjee, Ayan

    2016-01-01

    In present paper a spherically symmetric stellar configuration has been analyzed by assuming the matter distribution of the stellar configuration is anisotropic in nature and compared with the realistic objects, namely, the low mass X-ray binaries (LMXBs) and X-ray pulsars. The analytic solution has been obtained by utilizing the dark energy equation of state for the interior solution corresponding to the Schwarzschild exterior vacuum solution at the junction interface. Several physical properties like energy conditions, stability, mass-radius ratio, and surface redshift are described through mathematical calculations as well as graphical plots. It is found that obtained mass-radius ration of the compact stars candidates like 4U 1820-30, PSR J 1614-2230, Vela X-1 and Cen X-3 are very much consistent with the observed data by Gangopadhyay et al. (Mon. Not. R. Astron. Soc. 431, 3216 (2013)). So our proposed model would be useful in the investigation of the possible clustering of dark energy.

  11. PIRATE: A Remotely Operable Telescope Facility for Research and Education

    Science.gov (United States)

    Holmes, S.; Kolb, U.; Haswell, C. A.; Burwitz, V.; Lucas, R. J.; Rodriguez, J.; Rolfe, S. M.; Rostron, J.; Barker, J.

    2011-10-01

    We introduce PIRATE, a new remotely operable telescope facility for use in research and education, constructed from off-the-shelf hardware, operated by The Open University. We focus on the PIRATE Mark 1 operational phase, in which PIRATE was equipped with a widely used 0.35 m Schmidt-Cassegrain system (now replaced with a 0.425 m corrected Dall-Kirkham astrograph). Situated at the Observatori Astronòmic de Mallorca, PIRATE is currently used to follow up potential transiting extrasolar planet candidates produced by the SuperWASP North experiment, as well as to hunt for novae in M31 and other nearby galaxies. It is operated by a mixture of commercially available software and proprietary software developed at the Open University. We discuss problems associated with performing precision time-series photometry when using a German Equatorial Mount, investigating the overall performance of such off-the-shelf solutions in both research and teaching applications. We conclude that PIRATE is a cost-effective research facility, and it also provides exciting prospects for undergraduate astronomy. PIRATE has broken new ground in offering practical astronomy education to distance-learning students in their own homes.

  12. Polarimetry of an Intermediate-age Open Cluster: NGC 5617

    CERN Document Server

    Orsatti, Ana Maria; Vergne, M Marcela; Martinez, Ruben E; Vega, E Irene

    2010-01-01

    We present polarimetric observations in the UBVRI bands of 72 stars located in the direction of the medium age open cluster NGC 5617. Our intention is to use polarimetry as a tool membership identification, by building on previous investigations intended mainly to determine the cluster's general characteristics rather than provide membership suitable for studies such as stellar content and metallicity, as well as study the characteristics of the dust lying between the Sun and the cluster. The obsevations were carried out using the five-channel photopolarimeter of the Torino Astronomical Observatory attached to the 2.15m telescope at the Complejo Astron\\'omico El Leoncito (CASLEO; Argentina. We are able to add 32 stars to the list of members of NGC 5617, and review the situation for others listed in the literature. In particular, we find that five blue straggler stars in the region of the cluster are located behind the same dust as the member stars are and we confirm the membership of two red giants. The propo...

  13. Rovibrational CO analysis in PDR models

    Science.gov (United States)

    Stancil, Phillip C.; Cumbee, Renata; Zhang, Ziwei; Walker, Kyle M.; Yang, Benhui; Ferland, Gary J.

    2016-01-01

    CO is one of the most important molecules in the interstellar medium and in photodissociation regions (PDRs). Most of the extragalactic non-stellar IR to submm CO emission originates in PDRs. (Hollenbach & Tielens 1999). Pure rotational CO lines have been previously used in PDR models to provide density, temperature, and other diagnostics. However, for environments exposed to intense UV radiation, CO vibrational levels become significantly populated. Given new calculations of rovibrational collisional rate coefficients for CO-H (Walker et al. 2015, Song et al. 2015) and CO-H2 (Yang et al. 2015), we explore their effects in standard Cloudy PDR (Ferland et al. 2013) and Radex (van der Tak et al. 2007) models. In particular, CO vibrational transitions due to H2 collisions are studied for the first time using reliable full-dimensional CO-H2 collisional data.Ferland, G. J., et al. 2013, Rev. Mex. Astron. y Astrof., 49, 137Hollenbach, D. J. & Tielens, A. G. G. M. 1999, RMP, 71, 173Song, L., et al. 2015, ApJ, in pressvan der Tak, F. F. S, et al. 2007, A&A, 468, 627Walker, K. M., et al. 2015, ApJ, 811, 27Yang, B., et al. 2015, Nature Comm., 6, 6629This work was supported in part by NASA grants NNX12AF42G and NNX15AI61G.

  14. Hard X-ray/gamma-ray and centimeter/millimeter observations of the 3 November 2003 solar flare

    Science.gov (United States)

    Vilmer, N.; Dauphin, C.; Magun, A.; Lüthi, T.

    The 3 November 2003 flare at 09 50 UT was observed in the Hard X-ray HXR Gamma-ray GR domain by RHESSI Ramaty High Energy Solar Spectroscopic Imager and at centimeter millimeter wavelengths by the Bumishus observatory and the Bern nulling interferometer see e g Dauphin et al Adv Space Res 35 1805 2005 and Dauphin et al Astron Astrophys in press 2006 We shall further study here the shape of the HXR GR continuum observed by RHESSI and show that the spectrum presents evidence of a hardening of the accelerated electron distributions towards the MeV range We shall also discuss the relationship between HXR GR and centimeter millimeter emitting electrons and deduce the energy content in accelerated electrons The present results will be discussed with respect to results previously published on the comparison of bremsstrahlung and gyrosynchrotron emitting electrons obtained from observations of HXR GR spectra in a wide energy range and of centimeter millimeter radiation in a wide frequency range

  15. Optical Spectroscopic Observations of Gamma-ray Blazar Candidates. V. TNG, KPNO, and OAN Observations of Blazar Candidates of Uncertain Type in the Northern Hemisphere

    CERN Document Server

    Crespo, N Álvarez; Ricci, F; Landoni, M; Patiño-Álvarez, V; Massaro, F; D'Abrusco, R; Paggi, A; Chavushyan, V; Jiménez-Bailón, E; Torrealba, J; Latronico, L; La Franca, F; Smith, Howard A; Tosti, G

    2016-01-01

    The extragalactic $\\gamma$-ray sky is dominated by emission from blazars, a peculiar class of active galactic nuclei (AGNs). Many of the $\\gamma$-ray sources included in Fermi -Large Area Telescope Third Source catalog (3FGL) are classified as a blazar candidate of uncertain type (BCU) because there is no optical spectra available in the literature to confirm their nature. In 2013 we started a spectroscopic campaign to look for the optical counterparts of the BCUs and of the Unidentified $\\gamma$-ray Sources. The main goal of our investigation is to confirm the blazar nature of these sources having peculiar properties as compact radio emission and/or selected on the basis of their infrared (IR) colors. Whenever possible we also determine their redshifts. Here we present the results of the observations carried out in the Northern hemisphere in 2013 and 2014 at Telescopio Nazionale Galilleo (TNG), Kitt Peak National Observatory (KPNO) and Observatorio Astron\\'omico Nacional (OAN) in San Pedro M\\'artir. In this ...

  16. Kelvin--Helmholtz instability in an active region jet observed with \\emph{Hinode}

    CERN Document Server

    Zhelyazkov, I; Srivastava, A K

    2015-01-01

    Over past ten years a variety of jet-like phenomena were detected in the solar atmosphere, including plasma ejections over a range of coronal temperatures being observed as extreme ultraviolet (EUV) and X-ray jets. We study the possibility for the development of Kelvin--Helmholtz (KH) instability of transverse magnetohydrodynamic (MHD) waves traveling along an EUV jet situated on the west side of NOAA AR 10938 and observed by three instruments on board Hinode on 2007 January 15/16 (Chifor et al., Astron. Astrophys.481, L57 (2008)). The jet was observed around LogT_e = 6.2 with up-flow velocities exceeded 150 km/s. Using Fe XII lambda186 and lambda195 line ratios, the measured densities were found to be above LogN_e = 11. We have modeled that EUV jet as a vertically moving magnetic flux tube (untwisted and weakly twisted) and have studied the propagation characteristics of the kink (m=1) mode and the higher m modes with azimuthal mode numbers m=2,3,4. It turns out that all these MHD waves can become unstable a...

  17. Interaction of a circularly polarised gravitational wave with a charged particle in a static magnetic background

    Science.gov (United States)

    Gangopadhyay, Sunandan; Saha, Anirban; Saha, Swarup

    2015-06-01

    Interaction of a charged particle in a static magnetic background, i.e., a Landau system with circularly polarised gravitational wave (GW) is studied quantum mechanically in the long wavelength and low velocity limit. We quantize the classical Hamiltonian following (Speliotopoulos in Phys Rev D 51:1701, 1995). The rotating polarization vectors of the circularly polarized GW are employed to form a unique directional triad which served as the coordinate axes. The Schrodinger equations for the system are cast in the form of a set of coupled linear differential equations. This system is solved by iterative technique. We compute the time-evolution of the position and momentum expectation values of the particle. The results show that the resonance behaviour obtained earlier (Macedo and Nelson in Astrophys J 362:584, 1990; Papadopoulos in Astron Astrophys 396:1045, 2002) by classical treatements of the system has a quantum analogue not only for the linearly polarized GW (Gangopadhyay and Saha in Mod Phys Lett A 27:1250192, 2012), but for circularly polarized GW as well.

  18. WSO-UV project for high-resolution spectroscopy and imaging

    Science.gov (United States)

    Sachkov, M.; Shustov, B.; Savanov, I.; Gómez de Castro, A. I.

    2014-01-01

    During the last three decades, astronomers have had practically continuous access to the 100-300 nm spectral range that is unreachable with ground-based instruments but where astrophysical processes can be efficiently studied with unprecedented capability since the resonance lines of the most abundant atoms and ions at temperatures between 3 000 and 300 000 K are in the UV. The successful International Ultraviolet Explorer (IUE) observatory, Russian ASTRON mission and successor instruments such as the COS and STIS spectrographs on-board the Hubble Space Telescope (HST) demonstrate the major impact that observations in the UV wavelength range have had on modern astronomy. The access to space-based observatories is very limited. For the next decade, for the post-HST era, the World Space Observatory UltraViolet (WSO-UV) will be the only large telescope class mission for UV observations, both spectroscopic and imaging. By its potential, the WSO-–UV mission is similar to the HST, though it exceeds the HST/STIS in sensitivity by a factor 5-10, but all the observing time will be available for UV astronomy. In this paper, we briefly outline the WSO-UV mission model, instrumentation description, science management plan as well as some of the key science issues that WSO-UV will address during its lifetime.

  19. Phase Retrieval Problem. Application to VLBI Mapping of Active Galactic Nuclei

    CERN Document Server

    Bajkova, A T

    2012-01-01

    The well-known phase problem which means image reconstruction from only spectrum magnitude without using any spectrum phase information is considered basically in application to VLBI mapping of compact extragalactic radio sources (active galactic nuclei). The method proposed for phaseless mapping is based on the reconstruction of the spectrum magnitude on the entire UV plane from the measured visibility magnitude on a limited set of points and the reconstruction of the sought-for image of the source by Fienup's error-reduction iterative algorithm from the spectrum magnitude reconstructed at the first stage. It is shown that the technique used ensures unique solution (within a class of equivalent functions) for AGNs with typical structure morphology "bright core + week jet". The method proposed can be used, for example, for imaging with ultra-high resolution using a space{ground radio interferometer with a space antenna in a very high orbit ("RadioAstron"). In this case, a multi-element interferometer essentia...

  20. La familia de números metálicos

    Directory of Open Access Journals (Sweden)

    Vera W. de Spinadel

    2003-01-01

    Full Text Available En este trabajo vamos a introducir una nueva familia de números irracionales cuadráticos positivos. Se llama familia de números metálicos [1], [2], [3], [4] y su miembro más importante es el número de oro φ . Entre sus parientes, podemos mencionar el número de plata, el número de bronce, el número de cobre, el número de níquel, etc. Los miembros de dicha familia gozan de propiedades matemáticas comunes que son fundamentales en la investigación actual sobre la estabilidad de macro- y microsistemas físicos, desde la estructura interna del ADN hasta las galaxias astronómicas. Los resultados más notables de esta nueva investigación son los siguientes: • Los miembros de la familia intervienen en la determinación del comportamiento cuasi-periódico de sistemas dinámicos no lineales, constituyendo una herramienta invalorable en la búsqueda de rutas universales al caos. • Las sucesiones numéricas basadas en los miembros de esta familia, satisfacen muchas propiedades aditivas y simultáneamente son sucesiones geométricas, por lo que han sido utilizadas con frecuencia como base de muchos sistemas de proporciones.

  1. Ozone exposure of field-grown winter wheat affects soil mesofauna in the rhizosphere

    International Nuclear Information System (INIS)

    A 2-year open-top chamber experiment with field-grown winter wheat (Triticum aestivum L. cv. Astron) was conducted to examine the effects of ozone on plant growth and selected groups of soil mesofauna in the rhizosphere. From May through June in each year, plants were exposed to two levels of O3: non-filtered (NF) ambient air or NF+ 40 ppb O3 (NF+). During O3 exposure, soil sampling was performed at two dates according to different plant growth stages. O3 exposure reduced above- and below-ground plant biomass in the first year, but had little effect in the second year. The individual density of enchytraeids, collembolans and soil mites decreased significantly in the rhizosphere of plants exposed to NF+ in both years. Differences were highest around anthesis, i.e. when plants are physiologically most active. The results suggest that elevated O3 concentrations may influence the dynamic of decomposition processes and the turnover of nutrients. - Ozone reduced the individual densities of enchytraeids, collembolans and soil mites in the rhizosphere of winter wheat indirectly via the plant-soil-system.

  2. An Experiment to Investigate the Role of Neutrals in Magnetic Reconnection

    Science.gov (United States)

    Lawrence, Eric; Yoo, Jongsoo; Yamada, Masaaki; Ji, Hantao; Dorfman, Seth; Tharp, Tim; Myers, Clayton

    2010-11-01

    Magnetic reconnection in the solar chromosphere has become a topic of recent interest as it may be a source of energy transfer into the corona [1], and observations show evidence of fast reconnection [2]. Unlike the corona, the plasma in the chromosphere is relatively cool (T ˜10^4 K) and is weakly to partially ionized (nn/n ˜10^0-10^4). Furthermore, simulations have shown that the reconnection rate can depend on the ionization fraction and neutral collisionality [3]. Damping due to ion-neutral viscosity may also play a role. In the Magnetic Reconnection Experiment (MRX), we plan to study the effects of neutrals on reconnection in a controlled laboratory setting. A optical probe diagnostic is used to measure neutral density, and we plan to develop a UV diagnostic to facilitate comparisons with solar observations. Initial pressure scans have shown that we can access a parameter space relevant to the chromosphere. [4pt] [1] P. A. Sturrock, ApJ 521, 451 (1999).[0pt] [2] J. Chae, et al., J. Korean Astron. Soc., 36, 13 (2003).[0pt] [3] P. D. Smith, et al., A&A 486, 569 (2008).

  3. Russian Space Probes Scientific Discoveries and Future Missions

    CERN Document Server

    Harvey, Brian

    2011-01-01

    The Soviet Union began the exploration of space with the launch of Sputnik in 1957, well over 50 years ago, and sent the first probes to the Moon, Mars, and Venus. Less well known is what these probes actually found out. What were the discoveries of Russian space science? What new discoveries may we expect in the future? Who were Russia's most important scientists? Russian Space Probes gives for the first time the definitive history of Soviet-Russian space science, and is the first book to assess the actual achievements of the Russian space program in furthering our knowledge of the Solar System. Among other projects covered are missions such as Elektron, which mapped the Earth's radiation belts; the astrophysical observatories Astron, Kvant, Gamma, and Granat; Proton, which trapped cosmic rays; Prognoz, which measured solar radiation; and the Interball, Aktivny, APEX, and Magion mission in which satellites chased each other in the Earth's magnetic tail. The final part of the book examines the future of Russ...

  4. Relations between Microwave Bursts and near-Earth High-Energy Proton Enhancements and their Origin

    CERN Document Server

    Grechnev, V V; Meshalkina, N S; Chertok, I M

    2015-01-01

    We further study the relations between parameters of bursts at 35 GHz recorded with the Nobeyama Radio Polarimeters during 25 years, on the one hand, and solar proton events, on the other hand (Grechnev et al. in Publ. Astron. Soc. Japan 65, S4, 2013a). Here we address the relations between the microwave fluences at 35 GHz and near-Earth proton fluences above 100 MeV in order to find information on their sources and evaluate their diagnostic potential. A correlation was found to be pronouncedly higher between the microwave and proton fluences than between their peak fluxes. This fact probably reflects a dependence of the total number of protons on the duration of the acceleration process. In events with strong flares, the correlation coefficients of high-energy proton fluences with microwave and soft X-ray fluences are higher than those with the speeds of coronal mass ejections. The results indicate a statistically larger contribution of flare processes to high-energy proton fluxes. Acceleration by shock wave...

  5. The Rotation of the Earth: new models and concepts

    Directory of Open Access Journals (Sweden)

    E. F. Arias

    2006-01-01

    Full Text Available Anales del siglo XX, las observaciones VLBI pusieron en evidencia inconsistencias del orden de varios milésimos de segundo de arco en los modelos convencionales que representaban la posición del polo celeste. La Unión Astronómica Internacional (IAU, conjuntamente con la Unión Internacional de Geofísica y Geodesia (IUGG, establecieron el grupo de trabajo IAU/IUGG sobre la nutación para una Tierra no-rígida y le encargaron la elaboración de un nuevo modelo para un mejor ajuste de las observaciones. Esta tarea concluyó con el modelo de precesión-nutación IAU 2000, basado en la función de transferencia de Mathews et al. (2002. En este trabajo se presentan las principales características del modelo, se introducen los nuevos conceptos y se discute la transformación entre los sistemas de coordenadas terrestre y celeste.

  6. Critical Analysis of a Hypothesis of the Planetary Tidal Influence on Solar Activity

    CERN Document Server

    Poluianov, Stepan

    2014-01-01

    The present work is a critical revision of the hypothesis of the planetary tidal influence on solar activity published by Abreu et al. (Astron. Astrophys. 548, A88, 2012; called A12 here). A12 describes a hypothesis that planets can have an impact on the solar tachocline and therefore on solar activity. We checked the procedure and results of A12, namely the algorithm of planetary tidal torque calculation and the wavelet coherence between torque and heliospheric modulation potential. We found that the claimed peaks in long-period range of the torque spectrum are artefacts caused by the calculation algorithm. Also the statistical significance of the results of the wavelet coherence is found to be overestimated by an incorrect choice of the background assumption of red noise. Using a more conservative non-parametric random phase method, we found that the long-period coherence between planetary torque and heliospheric modulation potential becomes insignificant. Thus we conclude that the considered hypothesis of ...

  7. Bohr's Semiclassical Model of the Black Hole Thermodynamics

    Science.gov (United States)

    Pankovic, V.; Predojevic, M.; Grujic, P.

    2008-06-01

    ekenstein, J. D. 1973, Phys. Rev. D, 7, 2333 Bekenstein, J. D. 1994, gr-qc/9409015v2 Bekenstein, J. D. 1998, gr-qc/9808028v3 Frasca, M. 2005, hep-th/0411245v4 Grujic, P. V. 1993, Bull. Astron. Belgrade, 147, 15 Hawking, S. W. 1975, Comm. Math. Phys., 43, 199 Hawking, S. W. 1979, in "General Relativity, an Einstein Centenary Survey," Eds. S. W. Hawking and W. Israel (Cambridge: Cambridge University Press) Nagatani, Y. 2007, Progr. Theor. Phys. Suppl., 164, 54 Nicolai,H., Peeters, K., & Zamaklar, M. 2005, Class. Quantum Grav., 22, R193 Norcliffe A. 1975, in "Case Studies in Atomic Physics - Vol. 4," Eds. E. W. McDaniel and M. R. McDowell (Amsterdam: North-Holland), 46 Page, D. N. 2004, hep-th/0409024 Pavon, D. 2007, J. Phys. A, 40, 6865 Proline, B. 2006, hep-th/0607227 Ram, B. 2000, Phys. Lett. A, 265, 1 Ram, B., Ram, A, Ram, N. 2005, The Quantum Black Hole, gr-qc/0504030 Samuel, J., & Chowdhury, S. R. 2007, Class. Quantum Grav., 24, F47 Strominger, D. N., Vafa, C. 1996, Phys. Lett. B, 339, 99 Wald, R. M. 1997, gr-qc/9702022 Wald, R. M. 1999, gr-qc/9912119

  8. Bodily tides near the 1:1 spin-orbit resonance: correction to Goldreich's dynamical model

    Science.gov (United States)

    Williams, James G.; Efroimsky, Michael

    2012-12-01

    Spin-orbit coupling is often described in an approach known as " the MacDonald torque", which has long become the textbook standard due to its apparent simplicity. Within this method, a concise expression for the additional tidal potential, derived by MacDonald (Rev Geophys 2:467-541, 1994), is combined with a convenient assumption that the quality factor Q is frequency-independent (or, equivalently, that the geometric lag angle is constant in time). This makes the treatment unphysical because MacDonald's derivation of the said formula was, very implicitly, based on keeping the time lag frequency-independent, which is equivalent to setting Q scale as the inverse tidal frequency. This contradiction requires the entire MacDonald treatment of both non-resonant and resonant rotation to be rewritten. The non-resonant case was reconsidered by Efroimsky and Williams (Cel Mech Dyn Astron 104:257-289, 2009), in application to spin modes distant from the major commensurabilities. In the current paper, we continue this work by introducing the necessary alterations into the MacDonald-torque-based model of falling into a 1-to-1 resonance. (The original version of this model was offered by Goldreich (Astron J 71:1-7, 1996). Although the MacDonald torque, both in its original formulation and in its corrected version, is incompatible with realistic rheologies of minerals and mantles, it remains a useful toy model, which enables one to obtain, in some situations, qualitatively meaningful results without resorting to the more rigorous (and complicated) theory of Darwin and Kaula. We first address this simplified model in application to an oblate primary body, with tides raised on it by an orbiting zero-inclination secondary. (Here the role of the tidally-perturbed primary can be played by a satellite, the perturbing secondary being its host planet. A planet may as well be the perturbed primary, its host star acting as the tide-raising secondary). We then extend the model to a

  9. Meteor bodies entering the Martian atmosphere: possible impact consequences

    Science.gov (United States)

    Kuznetsova, Daria; Gritsevich, Maria

    on the Martian surface, different authors suggest that the atmosphere should have been denser at the time of these meteorites' fall. We apply our theory to determine the changing of impact consequences with the increasing atmospheric density on Mars. Acknowledgements: This work is conducted under the partial support from the Russian Foundation for Basic Research projects Nos. 14-08-00204 and 13-07-00276, and the Academy of Finland. References: [1] Christou A.A. (2010) Mon. Not. R. Astron. Soc. 402, 2759-2770. [2] Bland P.A. and Smith T.B. (2000) Icarus, 144, 21-26. [3] Domokos A. et al. (2007) Icarus, 191, 141-150. [4] Stulov V. P. et al. (1995) Aerodynamics of Bolides. Nauka, Moscow. (In Russian) [5] Ceplecha Z. et al. (1998) Space Science Reviews, 84, 327-471. [6] Gritsevich M.I. (2007) Solar System Research, 41(6), 509-514. [7] Gritsevich M.I. et al. (2012) Cosmic Research, 50(1), 56-64. [8] Gritsevich M.I. (2009) Advances in Space Research, 44(3), 323-334. [9] Chappelow J.E. and Sharpton V.L. (2006) Icarus, 184, 424-435. [10] Beech M. and Coulson I.M. (2010) Mon. Not. R. Astron. Soc., 404, 1457-1463. [11] Chappelow J.E. and Golombek M.P. (2010) J. of Geophys. Res., 115, E00F07.

  10. The low-metallicity QSO HE 2158 - 0107: a massive galaxy growing by accretion of nearly pristine gas from its environment?

    Science.gov (United States)

    Husemann, B.; Wisotzki, L.; Jahnke, K.; Sánchez, S. F.

    2011-11-01

    The metallicities of active galactic nuclei (AGN) are usually well above solar in their narrow-line regions, often reaching up to several times solar in their broad-line regions independent of redshift. Low-metallicity AGN are rare objects that have so far always been associated with low-mass galaxies hosting low-mass black holes (MBH106M⊙). We present integral field spectroscopy data of the low-redshift (z = 0.212) quasi-stellar object (QSO) HE 2158 - 0107 for which we find strong evidence of sub-solar NLR metallicities associated with a massive black hole (MBH ~ 3 × 108M⊙). The QSO is surrounded by a large extended emission-line region reaching out to 30 kpc from the QSO in a tail-like geometry. We present optical and near-infrared images and investigate the properties of the host galaxy. The host of HE 2158 - 0107 is most likely a very compact bulge-dominated galaxy with a size of re ~ 1.4 kpc. The multi-colour spectral energy distribution (SED) of the host is quite blue, indicative of a significant young age stellar population formed within the last 1 Gyr. A 3σ upper limit of Lbulge,H feeding of the black hole. HE 2158 - 0107 appears to represent a particular phase of substantial black hole and galaxy growth that can be observationally linked with the accretion of external material from its environment. Based on observations collected at the Centro Astronómico Hispano Alemán (CAHA) at Calar Alto, operated jointly by the Max-Planck-Institut für Astronomie and the Instituto de Astrofísica de Andalucía (CSIC) and on observations collected at the European Organisation for Astronomical Reasearch in the Southern Hemisphere, Chile (program 070.B-0418).

  11. Mutual Events in the Uranian satellite system in 2007

    Science.gov (United States)

    Arlot, J. E.

    2008-09-01

    ones. The predictions of the mutual events has been made [5] and are also available at the web address: http://www.imcce.fr/phemu09. References [1] Laskar J., Jacobson R.A.. (1987) Astron. Astrophys, 188, 212-224. [2] Arlot J.E. et al. (2006) Astron. Astrophys., 456, 1173-1179. [3] Showalter M., Lissauer J. (2006) Science, 311, 973- 977. [4] Arlot J.E. (2008) Astron. Astrophys., 478, 285-298. [5] Arlot J.E. et al. (2008) Astron. Astrophys., 485, 293- 298.

  12. Last 250 years climate reconstruction inferred from geothermal measurements in the Czech Republic

    Science.gov (United States)

    Bodri, L.; Čermák, V.

    1998-06-01

    The subsurface of the Earth has a certain capability to remember what has happened on its surface tens to hundreds of years ago. Ground surface temperature (GST) history, reflecting past climate conditions, can be evaluated by analysing the excursions left on the present-day temperature-depth distribution measured by precise temperature loggings in the boreholes. Temperature logs from fifteen selected holes were inverted into GST histories to assess the corresponding climatic changes. These temperature records generally represent typical conditions existing on the territory of the Czech Republic. In combination with the GST reconstructions from our previous works, these data were used to assess the regional pattern of the last 250-year climatic change. The GSTs were obtained by applying the generalized least-squares inversion method [Jackson, D.D., 1972. Interpretation of inaccurate, insufficient and inconsistent data. Geophys. J. R. Astron. Soc. 28, 97-109], whereby the additional information on interdependence of both measured data and climate changes can be incorporated into the model in the form of covariance matrices. Three main episodes can be distinguished in the last 250 years: a warm period between 1790 and 1830, a slightly colder period in 1940-1960, and a general warming with the average rates of 0.01-0.03 K/year since then. The geographical distribution of the recent warming rate may indicate an impact of human activities. The verification of the GST assessment was accomplished by the independent past climate reconstructions gained by the use of historical sources and instrumental records.

  13. Motivation and challenge to capture both large-scale and local transport in next generation accretion theory

    Science.gov (United States)

    Blackman, Eric G.; Nauman, Farrukh

    2015-10-01

    > Accretion disc theory is less developed than stellar evolution theory although a similarly mature phenomenological picture is ultimately desired. While the interplay of theory and numerical simulations has amplified community awareness of the role of magnetic fields in angular momentum transport, there remains a long term challenge to incorporate the insights gained from simulations into improving practical models for comparison with observations. What has been learned from simulations that can lead to improvements beyond SS73 in practical models? Here, we emphasize the need to incorporate the role of non-local transport more precisely. To show where large-scale transport would fit into the theoretical framework and how it is currently missing, we review why the wonderfully practical approach of Shakura & Sunyaev (Astron. Astrophys., vol. 24, 1973, pp. 337-355, SS73) is necessarily a mean field theory, and one which does not include large-scale transport. Observations of coronae and jets, combined with the interpretation of results from shearing box simulations, of the magnetorotational instability (MRI) suggest that a significant fraction of disc transport is indeed non-local. We show that the Maxwell stresses in saturation are dominated by large-scale contributions and that the physics of MRI transport is not fully captured by a viscosity. We also clarify the standard physical interpretation of the MRI as it applies to shearing boxes. Computational limitations have so far focused most attention toward local simulations, but the next generation of global simulations should help to inform improved mean field theories. Mean field accretion theory and mean field dynamo theory should in fact be unified into a single theory that predicts the time evolution of spectra and luminosity from separate disc, corona and outflow contributions. Finally, we note that any mean field theory, including that of SS73, has a finite predictive precision that needs to be quantified

  14. Situação da Mulher na Astronomia Brasileira

    Science.gov (United States)

    Silva, Adriana V. R.

    2007-07-01

    O conteúdo desse texto surgiu de uma apresentação de mesmo título que fiz na XXXI Reunião Anual da Sociedade Astronômica Brasileira (SAB) em 2005. Esse tema foi inspirado originalmente pela minha participação no "2nd UIPAP International Conference on Women in Physics" realizado entre 23 e 25 de maio de 2005 no Rio de Janeiro. Essa é uma conferência internacional que acontece de três em três anos, sendo que a primeira ocorreu em 2002 na cidade de Paris, França. Participei dessa conferência como membro da delegação da Sociedade Brasileira de Física e um dos trabalhos que apresentei versava sobre a situação das mulheres na Astronomia brasileira, cujos resultados principais discorro a seguir. A situação das astrônomas, baseada nos dados dos sócios da SAB coletados no final de 2004, é comparada com a das físicas brasileiras e também com as nossas colegas americanas. Os dados identificam ainda uma maior evasão da carreira por parte das mulheres do que os homens. Alguns dos possíveis motivos da evasão são discutidos, como o desejo de constituir família e/ou isolamento. Resultados um tanto preocupantes com relação à distribuição de bolsas de produtividade do CNPq também são apresentados. As principais discussões e estratégias recomendadas nesse congresso são mencionadas de forma resumida ao final.

  15. Ritmitas mareales en la formación puncoviscana (S.L. en la localidad de Rancagua, Noroeste Argentino: Dinámica mareal y consideraciones paleoastronómicas

    Directory of Open Access Journals (Sweden)

    Vanina L López de Azarevich

    2010-03-01

    Full Text Available Las ritmitas mareales constituyen una clara evidencia de sedimentación afectada por las mareas pudiendo preservar los períodos mareales inducidos astronómicamente al momento del depósito. Las investigaciones de secuencias periódicas mareales, acrecionadas vertical o lateralmente, en unidades modernas y antiguas, han experimentado notables avances en los últimos 25 años, excepto en la transición Neoproterozoico-eocámbrico. La Formación Puncoviscana (NO argentino está compuesta en la localidad de Rancagua por litofacies de cara de playa hasta plataforma distal, la cual incluye ritmitas mareales de edad neo-proterozoico- cámbrica temprana. Los períodos lunares involucrados en la sedimentación pueden ser aproximados mediante análisis armónicos con transformadas rápidas de Fourier a partir de datos crudos de espesores de láminas. Un sistema semidiurno con períodos tropicales de 26,64 días fue reconocido, a partir del cual se calculó la distancia Tierra-Luna en 3,78 x1010 cm. Estos resultados proporcionan información relevante acerca de la evolución de la órbita lunar a través del tiempo geológico. Los datos sugieren un evento astrofísico singular e irrepetible durante la transición Paleo-Mesoproterozoico con incremento en la velocidad de alejamiento hasta el Cámbrico Temprano, con eventos menores discretos en el Cámbrico Temprano y Paleozoico Superior con disminución del 50% de la velocidad de alejamiento.

  16. ANALYSIS OF THE VERTICAL PROFILES OF HUMIDITY FROM RADIOSONDE SOUNDINGS LAUNCHED FROM ANTOFAGASTA

    Directory of Open Access Journals (Sweden)

    A. C. Otárola

    2011-01-01

    Full Text Available La región del Desierto de Atacama en el norte de Chile alberga algunos de los más recientes observatorios astronómicos, equipados con instrumentos que cubren varias bandas espectrales de interés, incluyendo: microondas, milimétrica, sub-milimétrica, infrarrojo medio, infrarrojo cercano y visible. Entre otros, la región hospeda al Very Large Telescope (VLT ubicado en Cerro Paranal, al Gran Arreglo Milimétrico de Atacama (ALMA, actualmente en construcción en el LLano de Chajnantor en la ladera occidental de la cordillera de Los Andes, y ha sido la región seleccionada para la instalación del Telescopio Europeo Extremadamente Grande (E-ELT. Debido al rol del vapor de agua atmosférico como una fuente de absorción de radiación en varias bandas espectrales, además de introducir fluctuaciones de fase en el frente de onda detectado por interferómetros tal como ALMA, hace del estudio de vapor de agua atmosférico un tema relevante en esta región. Este trabajo presenta un análisis de los perfiles verticales de humedad obtenidos por medio de radiosondas lanzadas desde las cercanías de la ciudad de Antofagasta, y se focaliza en la magnitud del sesgo seco en los perfiles de humedad relativa que se origina en un cambio de temperatura de los sensores de humedad relativa, respecto al ambiente circundante, producido por radiación solar directa sobre los sensores.

  17. Two Approaches in the Lunar Libration Theory: Analytical vs. Numerical Methods

    Science.gov (United States)

    Petrova, Natalia; Zagidullin, Arthur; Nefediev, Yurii; Kosulin, Valerii

    2016-10-01

    Observation of the physical libration of the Moon and the celestial bodies is one of the astronomical methods to remotely evaluate the internal structure of a celestial body without using expensive space experiments. Review of the results obtained due to the physical libration study, is presented in the report.The main emphasis is placed on the description of successful lunar laser ranging for libration determination and on the methods of simulating the physical libration. As a result, estimation of the viscoelastic and dissipative properties of the lunar body, of the lunar core parameters were done. The core's existence was confirmed by the recent reprocessing of seismic data Apollo missions. Attention is paid to the physical interpretation of the phenomenon of free libration and methods of its determination.A significant part of the report is devoted to describing the practical application of the most accurate to date the analytical tables of lunar libration built by comprehensive analytical processing of residual differences obtained when comparing the long-term series of laser observations with numerical ephemeris DE421 [1].In general, the basic outline of the report reflects the effectiveness of two approaches in the libration theory - numerical and analytical solution. It is shown that the two approaches complement each other for the study of the Moon in different aspects: numerical approach provides high accuracy of the theory necessary for adequate treatment of modern high-accurate observations and the analytic approach allows you to see the essence of the various kind manifestations in the lunar rotation, predict and interpret the new effects in observations of physical libration [2].[1] Rambaux, N., J. G. Williams, 2011, The Moon's physical librations and determination of their free modes, Celest. Mech. Dyn. Astron., 109, 85–100.[2] Petrova N., A. Zagidullin, Yu. Nefediev. Analysis of long-periodic variations of lunar libration parameters on the basis

  18. Properties of the ionized gas in HH202 - I. Results from integral field spectroscopy with PMAS

    Science.gov (United States)

    Mesa-Delgado, A.; López-Martín, L.; Esteban, C.; García-Rojas, J.; Luridiana, V.

    2009-04-01

    We present results from integral field spectroscopy with the Potsdam Multi-Aperture Spectrograph of the head of the Herbig-Haro (HH) object HH202 with a spatial sampling of 1 × 1arcsec2. We have obtained maps of different emission lines, physical conditions - such as electron temperature and density - and ionic abundances from recombination and collisionally excited lines. We present the first map of the Balmer temperature and of the temperature fluctuation parameter, t2. We have calculated the t2 in the plane of the sky, which is substantially smaller than that determined along the line of sight. We have mapped the abundance discrepancy factor (ADF) of O2+, ADF(O2+), finding its maximum value at the HH202-S position. We have explored the relations between the ADF(O2+) and the electron density, the Balmer and [OIII] temperatures, the ionization degree as well as the t2 parameter. We do not find clear correlations between these properties and the results seem to support that the ADF and t2 are independent phenomena. We have found a weak negative correlation between the O2+ abundance determined from recombination lines and the temperature, which is the expected behaviour in an ionized nebula, hence it seems that there is no evidence for the presence of supermetal-rich droplets in HII regions. Based on observations collected at the Centro Astronómico Hispano Alemán (CAHA) at Calar Alto, operated jointly by the Max-Planck Institut für Astronomie and the Instituto de Astrofísica de Andalucía (CSIC). E-mail: amd@iac.es

  19. RFI Mitigation Workshop

    Science.gov (United States)

    2010-05-01

    The increased sensitivity of passive instrumentation in radio astronomy and remote sensing and the intensifying active use of the spectrum have led to an increasing level of radio frequency interference (RFI) of the active services on the passive use of the spectrum. Advances in technology and computing have opened up new possibilities for mitigating the effects of certain classes of interference in the observing data. Interference in allocated bands always leads to data loss for the passive users of the spectrum even if interference mitigation is applied. However, interference mitigation in non-allocated spectral bands may facilitate the partial use of this spectrum for passive (non-interfering) observations. There is no generic method to mitigate all types of interference, so a multi-layered system approach may be advisable to reduce detrimental effects for a congested interference environment. Specific mitigation methods implemented at different points in the data acquisition chain will thus result in a cumulative mitigation effect on the data. This third RFI Mitigation Workshop considered RFI mitigation in radio astronomy in all its facets with the aim of facilitating the implementation of instrumental and data processing techniques. This workshop aimed to take a forward look at applications for the next generation of radio instruments, such as the SKA and its pathfinders and LOFAR, as well as considering their application to existing instruments. This workshop has been organized by ASTRON and NAIC, with support from the Engineering Forum of FP7 RadioNet, the SKA Project Development Office, and in collaboration with CRAF and IUCAF.

  20. Espectroscopía Espacial en el IR-Lejano

    Science.gov (United States)

    Goicoechea, Javier R.; Cernicharo, J.

    Debido a la opacidad atmosférica, el dominio IR--lejano del espectro electromagnético ha sido la última ventana en ser utilizada por la Astrofísica Molecular. El potencial que supone abrir este nuevo rango de frecuencias a través de la espectroscopía molecular ha comenzado a ser explotado con el Infrared Space Observatory (ISO). La sensibilidad de la instrumentación embarcada en dicho satélite no tiene comparación alguna con las escasas misiones espaciales, o a bordo de aviones, realizadas con anterioridad a su lanzamiento. En particular, casi todo el rango operativo de ISO en el IR--lejano no había sido explorado. El espectro IR--lejano de las fuentes más representativas de la galaxia era desconocido y los principales emisores de radiación, las moléculas, estaban por identificar. Las observaciones en el IR--lejano están especialmente indicadas para el estudio del gas caliente en las nubes moleculares del medio interestelar y en el interior de las envolturas circunestelares alrededor de estrellas evolucionadas. Algunas de estas fuentes; Sgr B2 en el Centro Galáctico y las Proto--Nebulosas Planetarias, constituyen uno de los objetos más paradigmáticos en nuestra comprensión de la complejidad química de La Galaxia. En esta contribución se presentan los resultados espectroscópicos más importantes de algunas de estas fuentes astronómicas.

  1. MEASURING AND FORECASTING OF PWV ABOVE LA SILLA, APEX AND PARANAL OBSERVATORIES

    Directory of Open Access Journals (Sweden)

    A. Chacón

    2011-01-01

    Full Text Available El contenido de vapor de agua precipitable (PWV en la atmósfera es muy importante en las regiones espectrales del infrarrojo y radio (sub-milimétrico. Por esto, el grupo de Astrometeorología de la Universidad de Valparaíso, ha desarrollado diferentes métodos para derivar el valor de esta variable desde mediciones con instrumentos hasta utilización de un modelo meteorológico para obtener su pronóstico. El objetivo de utilizar un modelo así es poder predecir las condiciones atmosféricas y apoyar la programación de las observaciones astronómicas. ESO posee varios medios para determinar PWV, utilizados en los observatorios, tales como radiometros infrarrojos (IRMA y espectrógrafos ópticos e infrarrojos. Al poseer estas herramientas se realizó una investigación para comparar las estimaciones de PWV con las mediciones in-situ entregadas por los radiosondas. Cuatro campañas dedicadas fueron realizadas durante el año 2009 en los observatorios La Silla, APEX y Paranal. Además, el grupo de astrometeorología implementó el modelo de pronóstico e investigación meteorológico (WRF con el propósito de simular el estado de la atmósfera (cada 6 horas y pronosticar el valor de PWV. Con estas simulaciones, los datos medidos por las campañas de radiosondas pueden ser clasificadas sin ópticamente y al mismo tiempo puede ser validado el modelo respecto al PWV.

  2. THE FORMATION AND EARLY EVOLUTION OF BROWN DWARFS VIEWED THROUGH THE ORION DISPERSED POPULATIONS

    Directory of Open Access Journals (Sweden)

    J. J. Downes

    2011-01-01

    Full Text Available Presentamos un resumen de los últimos resultados de un sondeo fotométrico y espectroscópico en curso, a gran escala, de estrellas de muy baja masa y enanas marrones con masas hasta M - 0.02 Mo, en las poblaciones dispersas de región de formación estelar de Orion OB1. El sondeo se basa en la combinación de observaciones fotométricas multi-época en las bandas R e I, obtenidas con la cámara Quest-I del Observatorio Astronómico Nacional de Venezuela, con datos en el cercano infrarrojo de los sondeos VISTA y 2MASS, abarcando un área total de -200 gd2. El sondeo fotométrico está siendo complementado con observaciones espectroscópicas de seguimiento realizadas con el instrumento Hectospec del telescopio MMT de 6.5 m, resultando hasta el momento en la confirmación espectroscópica de enanas marrones jóvenes con masas hasta -0.05 Mo cubriendo 6 gd2. Un resumen de los resultados basados en la muestra espectroscópicamente confirmada de miembros estelares y subestelares de Orion, así como en aquellos objetos que permanecen como candidatos se discuten con énfasis en la función inicial de masa, la dependencia de la distribución espacial como función de la masa, los excesos en el cercano infrarrojo y las fracciones de objetos con características tipo T-Tauri clásica o débil. Estos resultados se presentan y discuten en términos de las predicciones de los modelos de formación de enanas marrones en Downes, J. J., et al. (2011, en preparación.

  3. An all-sky extrasolar planet survey with multiple object, dispersed fixed-delay interferometers

    Directory of Open Access Journals (Sweden)

    Jian Ge

    2007-01-01

    Full Text Available La prospección de planetas extrasolares en todo el cielo (ASEPS se basará en telescopios de campo amplio (inicialmente el telescopio Sloan, para luego pasar a telescopios con mayores aperturas y una nueva generación de potentes espectrógrafos multiobjetos para dar seguimiento a millones de estrellas brillantes cercanas. ASEPS detectará decenas de miles de planetas extrasolares en las próximas dos décadas. Actualmente, ya se ha detectado un planeta (con periodo de 4.11 días y con 0.49 masas de Júpiter alrededor de una estrella de V = 8.05 mag (Ge et al. 2006, con el telescopio de 0.9-m Coude del KPNO, con el instrumento interferométrico de retardo fijo dispersado en su version mono-objeto. En las bandas visibles, ASEPS incrementará el número de sistemas planetarios en al menos dos órdenes de magnitud, dando así una poderosa base estad´ıstica para comprender las diferentes clases de sistemas planetarios. Este estudio tiene la capacidad de detectar planetas tipo Júpiter, tanto en masa como en distancia a su estrella madre. El estudio se desarrolla en el cercano infrarrojo y puede conducir al descubrimiento de planetas tipo terrestre en las zonas habitables de estrellas poco masivas. Las observaciones recientes con el telescopio Sloan demuestran la viabilidad de la búsqueda de planetas en forma multi-objeto en paralelo al reconocimiento espectroscópico de objetos d´ebiles SDSS. Esto sugiere que es posible combinar instrumentos Doppler con otros instrumentos astronómicos dentro de un solo paquete para incrementar la productividad científica y la eficiencia de operación, y así reducir los costos de instrumentos de los futuros grandes telescopios de campo amplio

  4. Mercury's capture into the 3/2 spin-orbit resonance including the effect of core-mantle friction

    Science.gov (United States)

    Correia, Alexandre C. M.; Laskar, Jacques

    2009-05-01

    The rotation of Mercury is presently captured in a 3/2 spin-orbit resonance with the orbital mean motion. The capture mechanism is well understood as the result of tidal interactions with the Sun combined with planetary perturbations [Goldreich, P., Peale, S., 1966. Astron. J. 71, 425-438; Correia, A.C.M., Laskar, J., 2004. Nature 429, 848-850]. However, it is now almost certain that Mercury has a liquid core [Margot, J.L., Peale, S.J., Jurgens, R.F., Slade, M.A., Holin, I.V., 2007. Science 316, 710-714] which should induce a contribution of viscous friction at the core-mantle boundary to the spin evolution. According to Peale and Boss [Peale, S.J., Boss, A.P., 1977. J. Geophys. Res. 82, 743-749] this last effect greatly increases the chances of capture in all spin-orbit resonances, being 100% for the 2/1 resonance, and thus preventing the planet from evolving to the presently observed configuration. Here we show that for a given resonance, as the chaotic evolution of Mercury's orbit can drive its eccentricity to very low values during the planet's history, any previous capture can be destabilized whenever the eccentricity becomes lower than a critical value. In our numerical integrations of 1000 orbits of Mercury over 4 Gyr, the spin ends 99.8% of the time captured in a spin-orbit resonance, in particular in one of the following three configurations: 5/2 (22%), 2/1 (32%) and 3/2 (26%). Although the present 3/2 spin-orbit resonance is not the most probable outcome, we also show that the capture probability in this resonance can be increased up to 55% or 73%, if the eccentricity of Mercury in the past has descended below the critical values 0.025 or 0.005, respectively.

  5. Frozen-wave instability in near-critical hydrogen subjected to horizontal vibration under various gravity fields.

    Science.gov (United States)

    Gandikota, G; Chatain, D; Amiroudine, S; Lyubimova, T; Beysens, D

    2014-01-01

    The frozen-wave instability which appears at a liquid-vapor interface when a harmonic vibration is applied in a direction tangential to it has been less studied until now. The present paper reports experiments on hydrogen (H2) in order to study this instability when the temperature is varied near its critical point for various gravity levels. Close to the critical point, a liquid-vapor density difference and surface tension can be continuously varied with temperature in a scaled, universal way. The effect of gravity on the height of the frozen waves at the interface is studied by performing the experiments in a magnetic facility where effective gravity that results from the coupling of the Earth's gravity and magnetic forces can be varied. The stability diagram of the instability is obtained. The experiments show a good agreement with an inviscid model [Fluid Dyn. 21 849 (1987)], irrespective of the gravity level. It is observed in the experiments that the height of the frozen waves varies weakly with temperature and increases with a decrease in the gravity level, according to a power law with an exponent of 0.7. It is concluded that the wave height becomes of the order of the cell size as the gravity level is asymptotically decreased to zero. The interface pattern thus appears as a bandlike pattern of alternate liquid and vapor phases, a puzzling phenomenon that was observed with CO2 and H2 near their critical point in weightlessness [Acta Astron. 61 1002 (2007); Europhys. Lett. 86 16003 (2009)].

  6. A Study on the Astronomical and Meteorological Magazine and the Communication and Popularization of Astronomy Knowledge%《观象丛报》与西方天文学知识的传播与普及

    Institute of Scientific and Technical Information of China (English)

    万映秋; 唐泉

    2014-01-01

    创刊于1915年的《观象丛报》是我国最早的天文学和气象学专业期刊,旨在传播和普及天文学和气象学知识。运用文献考证和分析方法,对《观象丛报》发表的与西方天文学有关的论文内容进行研究,指出其内容涉及天文学史、日月交食、行星运动、彗星、陨石以及天文教育等方面,这些论文对传播和普及西方天文学知识、促进我国近代天文学发展产生了积极的影响。%The Astronomical and Meteorological Magazine,first published in 1 915,was the earliest astronomical and meteorological magazine in China.Its aim is to spread and popularize the knowledge of astronomy and meteorology.Using the method of literature analysis and research,the papers related to modern astronomy in The Astronomical and Meteorological Magazine were studied,the conclusion is that these papers discussed history of astronomy,eclipses,planetary movement,comet,meteorite and education of astronomy and these papers exerted active influence on spreading and popularizing knowledge of astron-omy and promoted the development of Chinese modern astronomy.

  7. Frozen-wave instability in near-critical hydrogen subjected to horizontal vibration under various gravity fields.

    Science.gov (United States)

    Gandikota, G; Chatain, D; Amiroudine, S; Lyubimova, T; Beysens, D

    2014-01-01

    The frozen-wave instability which appears at a liquid-vapor interface when a harmonic vibration is applied in a direction tangential to it has been less studied until now. The present paper reports experiments on hydrogen (H2) in order to study this instability when the temperature is varied near its critical point for various gravity levels. Close to the critical point, a liquid-vapor density difference and surface tension can be continuously varied with temperature in a scaled, universal way. The effect of gravity on the height of the frozen waves at the interface is studied by performing the experiments in a magnetic facility where effective gravity that results from the coupling of the Earth's gravity and magnetic forces can be varied. The stability diagram of the instability is obtained. The experiments show a good agreement with an inviscid model [Fluid Dyn. 21 849 (1987)], irrespective of the gravity level. It is observed in the experiments that the height of the frozen waves varies weakly with temperature and increases with a decrease in the gravity level, according to a power law with an exponent of 0.7. It is concluded that the wave height becomes of the order of the cell size as the gravity level is asymptotically decreased to zero. The interface pattern thus appears as a bandlike pattern of alternate liquid and vapor phases, a puzzling phenomenon that was observed with CO2 and H2 near their critical point in weightlessness [Acta Astron. 61 1002 (2007); Europhys. Lett. 86 16003 (2009)]. PMID:24580229

  8. The meteorological stations of the 1.5 and 0.84 m telescopes of the OAN: description and results

    Directory of Open Access Journals (Sweden)

    R. Michel

    2001-01-01

    Full Text Available Se describen las estaciones meteorológicas de los telescopios de 1.5 y 0.84 m del Observatorio Astronómico Nacional en San Pedro Mártir (OAN. Las estaciones incluyen dispositivos para medir temperatura, presión atmosférica, humedad relativa y condiciones del viento. Todas las variables climáticas se miden continuamente, y sus valores medios se determinan cada 5 minutos y se escriben en el disco duro de la computadora de control. Esta información se actualiza continuamente en una página HTML a la que se tiene acceso desde la página del OAN. En este trabajo presentamos los resultados derivados de mediciones tomadas durante 2 años. Encontramos que el espejo primario de ambos telescopios está sustancialmente más caliente que el aire que lo rodea durante la noche (hasta 5 C. Este gradiente térmico deteriora la calidad de la imagen. En el telescopio de 1.5 m se puede corregir este efecto con un sistema de control de temperatura para el espejo primario. En el telescopio de 0.84 m, cuyo espejo primario está en una estructura cerrada, es probable que baste con instalar ventiladores que circulen aire entre el domo y el tubo cerrado. Durante la noche el aire está más frío dentro de ambos domos que afuera, por lo que es innecesario ventilar las cúpulas de estos telescopios.

  9. Contaminación de luz en Michoacán (campaña para cielos oscuros

    Directory of Open Access Journals (Sweden)

    Eduardo Antaramián Harutunián

    2001-01-01

    Full Text Available El deterioro del cielo nocturno debido a la contaminación luminica, es decir, el resplandor producido por la luz artificial que se pierde hacia el cielo es un tema que empieza a ser considerado en algunos países, tomando medidas para regular las características de la iluminación. En nuestra país casi no existe conciencia de la contaminación por luz, a pesar de que no sólo ayudaría a disfrutar del cielo nocturno sino también a ahorrar energía. Las observaciones astronómicas se han visto notablemente deterioradas en los últimos años po la contaminación luminica, siendo el caso más drástico el Observatorio Tonanzintla en Puebla, que está a tan sólo 13 km de la ciudad del mismo nombre, que tiene más de un millón de habitantes y que debería estar a más de 110 km. Con la fórmula de Walker se estimó la distancia de escape, es decir, aquélla que tiene un brillo menor del 10% cobre el brillo naturl. Se consideraron las poblaciones de Michoacán con mas de 30 000 habitantes de acuerdo con el censo de 2000, con las que se generó por interpretaci6n un mapa teórico del brillo de luz en Michoacán utilizando un sistema de información geográfica.

  10. Cosmic Rays in Thunderstorms

    Science.gov (United States)

    Buitink, Stijn; Scholten, Olaf; van den Berg, Ad; Ebert, Ute

    2013-04-01

    Cosmic Rays in Thunderstorms Cosmic rays are protons and heavier nuclei that constantly bombard the Earth's atmosphere with energies spanning a vast range from 109 to 1021 eV. At typical altitudes up to 10-20 km they initiate large particle cascades, called extensive air showers, that contain millions to billions of secondary particles depending on their initial energy. These particles include electrons, positrons, hadrons and muons, and are concentrated in a compact particle front that propagates at relativistic speed. In addition, the shower leaves behind a trail of lower energy electrons from ionization of air molecules. Under thunderstorm conditions these electrons contribute to the electrical and ionization processes in the cloud. When the local electric field is strong enough the secondary electrons can create relativistic electron run-away avalanches [1] or even non-relativistic avalanches. Cosmic rays could even trigger lightning inception. Conversely, strong electric fields also influence the development of the air shower [2]. Extensive air showers emit a short (tens of nanoseconds) radio pulse due to deflection of the shower particles in the Earth's magnetic field [3]. Antenna arrays, such as AERA, LOFAR and LOPES detect these pulses in a frequency window of roughly 10-100 MHz. These systems are also sensitive to the radiation from discharges associated to thunderstorms, and provide a means to study the interaction of cosmic ray air showers and the electrical processes in thunderstorms [4]. In this presentation we discuss the involved radiation mechanisms and present analyses of thunderstorm data from air shower arrays [1] A. Gurevich et al., Phys. Lett. A 165, 463 (1992) [2] S. Buitink et al., Astropart. Phys. 33, 1 (2010) [3] H. Falcke et al., Nature 435, 313 (2005) [4] S. Buitink et al., Astron. & Astrophys. 467, 385 (2007)

  11. Integral field spectroscopy of selected areas of the Bright bar and Orion-S cloud in the Orion nebula

    Science.gov (United States)

    Mesa-Delgado, A.; Núñez-Díaz, M.; Esteban, C.; López-Martín, L.; García-Rojas, J.

    2011-10-01

    We present integral field spectroscopy of two selected zones in the Orion nebula obtained with the Potsdam Multi-Aperture Spectrophotometer, covering the optical spectral range from 3500 to 7200 Å and with a spatial resolution of 1 arcsec. The observed zones are located on the prominent Bright bar and on the brightest area at the north-east of the Orion south cloud, both containing remarkable ionization fronts. We obtain maps of emission-line fluxes and ratios, electron density and temperatures, and chemical abundances. We study the ionization structure and morphology of both fields, whose ionization fronts show different inclination angles with respect to the plane of the sky. We find that the maps of electron density, O+/H+ and O/H ratios show a rather similar structure. We interpret this as produced by the strong dependence on density of the [O II] lines used to derive the O+ abundance, and that our nominal values of electron density - derived from the [S II] line ratio - may be slightly higher than the appropriate value for the O+ zone. We measure the faint recombination lines of O II in the field at the north-east of the Orion south cloud, allowing us to explore the so-called abundance discrepancy problem. We find a rather constant abundance discrepancy across the field and a mean value similar to that determined in other areas of the Orion nebula, indicating that the particular physical conditions of this ionization front do not contribute to this discrepancy. Based on observations collected at the Centro Astronómico Hispano Alemán (CAHA) at Calar Alto, operated jointly by the Max-Planck Institut für Astronomie and the Instituto de Astrofísica de Andalucía (CSIC).

  12. F(R) bouncing cosmology with future singularity in brane-anti-brane system

    Science.gov (United States)

    Sepehri, Alireza; Pradhan, Anirudh; Shoorvazi, Somayyeh

    2016-02-01

    Recently Odintsov and Oikonomou (Phys. Rev. D 92:024016, 2015b) proposed the origin of a Type IV singular bounce in a modified gravity and found an explicit form of F(R) which can generate this type of bouncing cosmological evolution. In this paper, we construct their model in string theory and show that interaction between branes is the main cause of F(R) bouncing cosmology. In our technique, N fundamental strings decay first to N M0-anti-M0-brane then, M0-branes link to each other, originate and form an M3-anti-M3 system. Our universe is located on one of these M3-branes and interact with the universe on another M3-brane via some scalars. The branes in this system wrap around each other and form a compacted system. This process causes to a contraction of universes and produces a contraction branch in a F(R) bouncing model of cosmology. Also, the relevant actions of compacted M3-branes include higher order of derivatives which lead to communication relations in generalized uncertainty principle. On the other hand, branes and anti-branes absorb each other, the radius of compactification is reduced, some of scalars gain negative square masses and become tachyons. This system is unstable, broken and branes rebound to non-compact state during an expansion branch. With opening of branes, some other scalars achieve to tachyon phase and consequently, this epoch stops. This process may be repeated in different branches. In this theory, the Type IV singularity occurs at t = ts, which is the time of producing tachyons between two branches. It is observed that the derived model is in good agreement with recent Planck data (Ade et al. in arXiv:1502.02114 [astro-ph.CO], 2015 and in Astron. Astrophys. 571:A22, 2014) and obtain the bouncing point.

  13. Comets 169P/NEAT and P/2003 T12 (SOHO): Two possible fragments of a common ancestor?

    Science.gov (United States)

    Sosa, Andrea; Fernández, Julio Angel

    2015-08-01

    In a recent work we analyzed the orbit evolution of Jupiter family comets in near-Earth orbits, and found some comets moving on highly stable orbits, like the near-Earth asteroids (Fernández & Sosa 2015). Two of them actually show almost identical orbits; they are the comets 169P/NEAT and P/2003 T12 (SOHO). Comet 169P seems to be a few km-sized, almost inactive body, while P/2003 T12 would be a very small comet, with a sub-km radius nucleus. We performed extended orbital integrations for the past 100,000 yr to further study their dynamical evolution. We found that the orbital parameters remain stable for several thousand years, with a well defined absolute minimum of their relative spatial distance around 2900 yr in the past, coincident with a low value of the relative velocity. This spatial minimum is in a remarkable good agreement with the results obtained by means of other methods to study common origins between pairs of asteroids (Vokrouhlicky & Nesvorny 2008, Southworth & Hawkins 1963), and to test a comet-meteor shower association (Drummond 1981). Our results support the hypothesis of a breakup of a parent body, that ocurred about 2900 yr ago, as the most probable origin for the studied pair of comets. Possible fragmentation mechanisms, like thermal stress, rotational instability, or colisions, are briefly discussed.References:Drumond J.D. 1981. Icarus 45, 545-553.Fernández J.A., & Sosa A. 2015. Submitted to Planetary & Space Science.Southworth R.B., & Hawkins, G.S. 1963. Smithson. Contrib. Astrophys. 7, 261-285Vokrouhlicky D., & Nesvorny D. 2008. Astron. J. 136, 280-290.

  14. Migration of Frosts from High-Albedo Regions of Pluto: what New Horizons Reveals

    Science.gov (United States)

    Buratti, Bonnie J.; Stern, S. A.; Weaver, Hal A.; Young, Leslie A.; Olkin, Cathy B.; Ennico, Kimberly; Binzel, Richard P.; Zangari, Amanda; Earle, Alissa M.

    2015-11-01

    With its high eccentricity and obliquity, Pluto should exhibit seasonal volatile transport on its surface. Several lines of evidence support this transport: doubling of Pluto’s atmospheric pressure over the past two decades (Young et al., 2013, Ap. J. 766, L22; Olkin et al., 2015, Icarus 246, 230); changes in its historical rotational light curve, once all variations due to viewing geometry have been modelled (Buratti et al., 2015; Ap. J. 804, L6); and changes in HST albedo maps (Buie et al., 2010, Astron. J. 139, 1128). New Horizons LORRI images reveal that the region of greatest albedo change is not the polar cap(s) of Pluto, but the feature informally named Tombaugh Regio (TR). This feature has a normal reflectance as high as ~0.8 in some places, and it is superposed on older, lower-albedo pre-existing terrain with an albedo of only ~0.10. This contrast is larger than any other body in the Solar System, except for Iapetus. This albedo dichotomy leads to a complicated system of cold-trapping and thermal segregation, beyond the simple picture of seasonal volatile transport. Whatever the origin of TR, it initially acted as a cold trap, as the temperature differential between the high and low albedo regions could be enormous, possibly approaching 20K, based on their albedo differences and assuming their normalized phase curves are similar. This latter assumption will be refined as the full New Horizons data set is returned.Over six decades of ground-based photometry suggest that TR has been decreasing in albedo over the last 25 years. Possible causes include changing insolation angles, or sublimation from the edges where the high-albedo material impinges on a much warmer substrate.Funding by the NASA New Horizons Project acknowledged.

  15. Uranus' Persistent Patterns and Features from High-SNR Imaging in 2012-2014

    Science.gov (United States)

    Fry, Patrick M.; Sromovsky, Lawrence A.; de Pater, Imke; Hammel, Heidi B.; Marcus, Phillip

    2015-11-01

    Since 2012, Uranus has been the subject of an observing campaign utilizing high signal-to-noise imaging techniques at Keck Observatory (Fry et al. 2012, Astron. J. 143, 150-161). High quality observing conditions on four observing runs of consecutive nights allowed longitudinally-complete coverage of the atmosphere over a period of two years (Sromovsky et al. 2015, Icarus 258, 192-223). Global mosaic maps made from images acquired on successive nights in August 2012, November 2012, August 2013, and August 2014, show persistent patterns, and six easily distinguished long-lived cloud features, which we were able to track for long periods that ranged from 5 months to over two years. Two at similar latitudes are associated with dark spots, and move with the atmospheric zonal flow close to the location of their associated dark spot instead of following the flow at the latitude of the bright features. These features retained their morphologies and drift rates in spite of several close interactions. A second pair of features at similar latitudes also survived several close approaches. Several of the long-lived features also exhibited equatorward drifts and latitudinal oscillations. Also persistent are a remarkable near-equatorial wave feature and global zonal band structure. We will present imagery, maps, and analyses of these phenomena.PMF and LAS acknowledge support from NASA Planetary Astronomy Program; PMF and LAS acknowledge funding and technical support from W. M. Keck Observatory. We thank those of Hawaiian ancestry on whose sacred mountain we are privileged to be guests. Without their generous hospitality none of our groundbased observations would have been possible.

  16. Health promotion, preventive and curative aspects of diseases in astrology.

    Science.gov (United States)

    Sharma, Bhuvnesh Kumar; Subhakta, P K J P; Narayana, A

    2007-01-01

    The whole universe is intermingling into a unit in the period of globalization. Different cultures, life-styles and sciences are co-operating with each other in this situation. World Health Organization is working towards collaborating all prevalent medical sciences for attainment of good health and family welfare for each and every individual by 2020. Astrology is a part of Indian heritage. Astrology means the art of predicting or determining the influence of the planets and stars on human affairs. The origin of this word is from Greek word astron, star + logos (discourse). The account of deeds of good and bad during the present life and previous lives, their consequences of health or ill health during this life i.e. what, when and how the things takes place will be clearly known through Astrology. Highly advanced knowledge related to Astrology on medicine is preserved in Indian scriptures and the knowledge was transmitted from generation to generation. It is also a good source for health promotion, preventive, curative and other medical aspects. Brief direction related to astrological medical aspects is also available in Ayurvedic literature (Carakasamhită, Suśrutasamhhită, Aşţăngasangraha, Aşţăngahŗdaya, Sărngadharasamhită , Băvaprakăśa etc.) Some Ayurvedic practitioners, scholars and scientists realize the need of astrological knowledge related to medicine in the present time. In ancient times physician, astrologer and purŏhita (Hindu priest) simultaneously looked after the health and family welfare of individual, families and country. Astrologer guides medication and suitable time for the better cure of ailments. Even the medicinal herbs were collected and treated at appropriate time for their efficacy. Astrology and Ayurvĕda are inseparable sciences of life. Hence, in this article, a concise astrological evaluation related to health promotion, preventive and curative aspects of Astrology is being presented. PMID:19580109

  17. Contribution of astrology in medicine -- a review.

    Science.gov (United States)

    Sharma, Bhuvnesh Kumar; Prasad, P V V; Narayana, A

    2007-01-01

    Astrology is the art of predicting or determining the influence of the planets and stars on human affairs. The origin of this word is from Greek word astron, star + logos (discourse). Both Ayurveda and Astrology have established a way of life in India since time immemorial. Highly advanced knowledge related to Astrology on medicine is preserved in Indian Holy scriptures and transmitted from generation to generation. Although both Astrology and medicine were developed as a part of religion in ancient India, astrological principles related to prevention, health care and relief from illness were applied as rituals (religious ceremonies). An astrologer gives guidance for taking medicines at suitable time for the best remedy of ailments. Even the medicinal herbs were collected and used at appropriate times for their efficacy. Astrology and Ayurveda are inseparable in human life. Role of the Astrology in healthy life and pathogenesis of the disease is well known to Indians. When a physician knows etiology of the disease, he attempts to treat the disease with specific medication, diet and life style and also avoiding causative factors. In a case where a physician is unable to understand the pathogenesis of the disease and to treat, the patient depends upon Astrology. Account of good and bad deeds during this life and previous lives, their consequences of health or ill health during this life which orderly, when, what and how will be clearly known through Astrology. It gives guidelines about welfare not only to human being but also to whole creation and also indicates about calamities and their solutions as possible extent. Hence a concise astrological evaluation related to prevention, health care, diagnosis and treatment of diseases is being presented in this article. PMID:19569452

  18. Museo Arqueológico de Petroglifos y el fomento del turismo en Venezuela

    Directory of Open Access Journals (Sweden)

    Yamile Delgado De Smith

    2005-11-01

    Full Text Available El Complejo Arqueológico de Vigirima (Venezuela es el mayor yacimiento de Petroglifos de América y el único lugar continental que presenta alineamientos megalíticos. Sin embargo, es poco conocido y ha sido aún menos estudiado, quedando a la saga de los proyectos de conservación y preservación patrimonial emprendidos por los organismos supranacionales. Se efectuó un registro sistemático y la clasificación estilística de los glifos y caracteres pétreos del complejo arqueológico de Vigirima. El análisis de las técnicas de elaboración, del substrato y su distribución espacio temporal muestran que los mismos fueron elaborados con diversos grados de especificidad por los grupos humanos que crearon estas expresiones de arte rupestre. Los contenidos y estilos informan sobre una sociedad en estrecha dependencia y en equilibrio frente a la naturaleza, en cuya organización tribal, de carácter igualitario, tendría un rol importante: el Chaman como mediador hombre-naturaleza y la mujer como símbolo de la reproducción de la fuerza humana de trabajo. Se presentan, adicionalmente, elementos contextuales que permiten datar la antigüedad del yacimiento y las tradiciones míticas de carácter mágico-religioso o astronómico, que pudieron motivarlo y finalmente se proponen alternativas para su conservación y el fomento del turismo.

  19. VizieR Online Data Catalog: Palomar/MSU nearby star spectroscopic survey (Hawley+ 1997)

    Science.gov (United States)

    Reid, I. N.; Hawley, S. L.; Gizis, J. E.

    1997-05-01

    The Third Catalogue of Nearby Stars (Gliese & Jahreiss, "Preliminary Version of the third Catalogue of Nearby Stars" (CNS3), 1991, catalog ) includes over 1850 stars which lie north of Dec.= -30° and are either identified as spectral type M, or are unclassified but with an absolute visual magnitude estimate MV > +8.0. Although there is no uniformity in selection criteria, and many of the stars lack basic data (radial velocities, spectral types, accurate photometry), the observational properties of these stars underlie most estimates of the fundamental characteristics of the Galactic Disk. We have obtained optical spectroscopy of 1746 of the 1876 stars -- the remaining 130 are binary companions of brighter stars and inaccessible to our observations. These spectra allow us, first, to exclude 61 stars as either degenerates or as misclassified earlier-type (B-K) stars lying beyond the 25 pc limit; to establish radial velocities accurate to ±10km/s for all stars confirmed as late-type dwarfs; to determine spectral types and absolute magnitudes from the TiO bandstrength, allowing more accurate distance estimates for stars with inaccurate (or no) trigonometric parallax measurements; and to identify stars with Hα emission (chromospherically active stars) and with strong CaH absorption (perhaps including some metal-poor disk subdwarfs). We have determined the nearby-star luminosity function from complete samples derived by applying both the distance limits defined by Wielen (1974, Highlights of Astron. 3, 395) and by using limits derived from our own analysis. Spectroscopic data for the southern stars (Dec.<-30°) in the PMSU survey are also presented. The data were combined with the data from paper I to obtain a list of all the magnetically active dMe stars in the survey. (11 data files).

  20. Quasi-biennial modulation of solar neutrino flux: connections with solar activity

    Science.gov (United States)

    Vecchio, A.; Laurenza, M.; D'alessi, L.; Carbone, V.; Storini, M.

    2011-12-01

    A quasi-biennial periodicity has been recently found (Vecchio et al., 2010) in the solar neutrino flux, as detected at the Homestake experiment, as well as in the flux of solar energetic protons, by means of the Empirical Modes Decomposition technique. Moreover, both fluxes have been found to be significantly correlated at the quasi-biennial timescale, thus supporting the hypothesis of a connection between solar neutrinos and solar activity. The origin of this connection is investigated, by modeling how the standard Mikheyev-Smirnov-Wolfenstein (MSW) effect (the process for which the well-known neutrino flavor oscillations are modified in passing through the material) could be influenced by matter fluctuations. As proposed by Burgess et al., 2004, by introducing a background magnetic field in the helioseismic model, density fluctuations can be excited in the radiative zone by the resonance between helioseismic g-modes and Alfvén waves. In particular, with reasonable values of the background magnetic field (10-100 kG), the distance between resonant layers could be of the same order of neutrino oscillation length. We study the effect over this distance of a background magnetic field which is variable with a ~2 yr period, in agreement with typical variations of solar activity. Our findings suggest that the quasi-biennial modulation of the neutrino flux is theoretically possible as a consequence of the magnetic field variations in the solar interior. A. Vecchio, M. Laurenza, V. Carbone, M. Storini, The Astrophysical Journal Letters, 709, L1-L5 (2010). C. Burgess, N. S. Dzhalilov, T. I. Rashba, V., B.Semikoz, J. W. F. Valle, Mon. Not. R. Astron. Soc., 348, 609-624 (2004).

  1. A New Interstellar Cyclic Molecule, Ethylene Oxide

    Science.gov (United States)

    Dickens, J. E.; Irvine, W. M.; Ohishi, M.; Ikeda, M.; Ishikawa, S.; Nummelin, A.; Hjalmarson, A.

    1997-12-01

    Ethylene oxide (c-C2H4O) is only the fourth known ring molecule identified in the interstellar medium, detected in the Galactic Center cloud SgrB2(N) by Dickens et al. (1997). It is the higher energy isomer of both the more familiar interstellar species acetaldehyde (CH3CHO) and the as yet undetected molecule vinyl alcohol (CH2CHOH). Dickens et al. (1997) reported a c-C2H4O molecular column density about an order of magnitude less than that reported for CH3CHO in SgrB2(N). This is a factor of 200 larger than the predictions of the new standard gas phase chemistry model of Lee, Bettens, and Herbst (1996), suggesting that the formation of c-C2H4O may be related to molecular formation on interstellar grains. We present observations of the c-C2H4O to CH3CHO abundance ratio in 5 additional molecular clouds. The data were taken in October 1997 with the Swedish-European Submillimeter Telescope in Chile. The confirmation of ethylene oxide in molecular clouds provides an appealing scenario for the first link in the chain of reactions leading to the origin of life, since it has been suggested as a possible pathway to the formation of the related cyclic molecule oxiranecarbonitrile (c-C3H3NO; cf., Dickens et al. 1996), a precursor to the synthesis of sugar phosphates which comprise the backbone of our molecular genetic structure. References: Dickens, J.E., Irvine, W.M., Ohishi, M., Ikeda, M., Ishikawa, S., Nummelin, A., and Hjalmarson, A. 1997, Astrophys. J., 489 (in press). Dickens, J.E. et al. 1996, Orig. Life Evol. Biosphere, 26, 97. Lee, H.-H., Bettens, R.P.A., and Herbst, E. 1996, Astron. Astrophys. Supp., 119, 111.

  2. Black holes in binary stellar systems and galactic nuclei

    Science.gov (United States)

    Cherepashchuk, A. M.

    2014-04-01

    In the last 40 years, following pioneering papers by Ya B Zeldovich and E E Salpeter, in which a powerful energy release from nonspherical accretion of matter onto a black hole (BH) was predicted, many observational studies of black holes in the Universe have been carried out. To date, the masses of several dozen stellar-mass black holes (M_BH = (4{-}20) M_\\odot) in X-ray binary systems and of several hundred supermassive black holes (M_BH = (10^{6}{-}10^{10}) M_\\odot) in galactic nuclei have been measured. The estimated radii of these massive and compact objects do not exceed several gravitational radii. For about ten stellar-mass black holes and several dozen supermassive black holes, the values of the dimensionless angular momentum a_* have been estimated, which, in agreement with theoretical predictions, do not exceed the limiting value a_* = 0.998. A new field of astrophysics, so-called black hole demography, which studies the birth and growth of black holes and their evolutionary connection to other objects in the Universe, namely stars, galaxies, etc., is rapidly developing. In addition to supermassive black holes, massive stellar clusters are observed in galactic nuclei, and their evolution is distinct from that of supermassive black holes. The evolutionary relations between supermassive black holes in galactic centers and spheroidal stellar components (bulges) of galaxies, as well as dark-matter galactic haloes are brought out. The launch into Earth's orbit of the space radio interferometer RadioAstron opened up the real possibility of finally proving that numerous discovered massive and highly compact objects with properties very similar to those of black holes make up real black holes in the sense of Albert Einstein's General Relativity. Similar proofs of the existence of black holes in the Universe can be obtained by intercontinental radio interferometry at short wavelengths \\lambda \\lesssim 1 mm (the international program, Event Horizon Telescope).

  3. Keplerian integrals, elimination theory and identification of very short arcs in a large database of optical observations

    Science.gov (United States)

    Gronchi, G. F.; Baù, G.; Milani, A.

    2016-09-01

    Modern asteroid surveys produce an increasingly large number of observations, which are grouped into very short arcs (VSAs) each containing a few observations of the same object in one single night. To decide whether two VSAs collected in different nights correspond to the same observed object we can attempt to compute an orbit with the observations of both arcs: this is called the linkage problem. Since the number of linkages to be attempted is very large, we need efficient methods of orbit determination. Using the first integrals of Kepler's motion we can write algebraic equations for the linkage problem, which can be put in polynomial form. In Gronchi et al. (Celest Mech Dyn Astron 123(2):105-122, 2015) these equations are reduced to a polynomial equation of degree 9: the unknown is the topocentric distance of the observed body at the mean epoch of one VSA. Here we derive the same equations in a more concise way, and show that the degree 9 is optimal in a sense that will be specified in Sect. 3.3. We also introduce a procedure to join three VSAs: from the conservation of angular momentum we obtain a polynomial equation of degree 8 in the topocentric distance at the mean epoch of the second VSA. For both identification methods, with two and three VSAs, we discuss how to discard solutions. Finally, we present some numerical tests showing that the new methods give satisfactory results and can be used also when the time separation between the VSAs is large. The low polynomial degree of the new methods makes them well suited to deal with the very large number of asteroid observations collected by the modern surveys.

  4. Exomol: Molecular Line Lists for Exoplanet and Other Atmospheres

    Science.gov (United States)

    Tennyson, Jonathan

    2013-06-01

    Spectral characterization of astrophysical objects cool enough to form molecules in their atmospheres (cool stars, extrosolar planets and planetary discs) requires considerable amounts of fundamental molecular data. The existing molecular line lists (with some exceptions) are generally not sufficiently accurate and complete. The ExoMol project is actively generating comprehensive line lists for all molecules likely to be observable in exoplanet atmospheres in the foreseeable future. This is a huge undertaking which will mean providing in excess of 10^{11} spectral lines for a large variety of molecular species, see Tennyson and Yurchenko (Mon. Not. R. Astron. Soc., 425, 21 (2012)) The physics of molecular absorptions is complex and varies between different classes of absorbers. The project is therefore be divided into following topics (a) diatomic, (b) triatomics, (c) tetratomics, (d) methane and (e) larger molecules. Special techniques are being developed to treat each case. The majority of diatomic systems to be tackled are open shell species involving a transition metal atom; the opacity is provided by the transitions between the many low lying electronic states of the system. The calculation of rotation-vibration line lists for closed-shell triatomic systems is now relatively straightforward provided enough care is taken in deriving the potential energy and dipole surfaces. An H_2S line list is nearing completion and studies on C_3 have started. Accurate rotation-vibration line lists for hot tetratomic molecules such as ammonia (complete), phosphine (nearing completion), acetylene (initial study published), hydrogen peroxide (initial study complete), SO_3 (room temperature line list complete) and formaldehyde, test what is computationally possible at present. An inital line list for hot (1000 K) methane has been completed and is being improved. Work on systems larger than this is just commencing. Data from this project can be accessed at www.exomol.com.

  5. El núcleo de instituciones científicas matritenses en el Paseo del Prado desde el siglo XVIII

    Directory of Open Access Journals (Sweden)

    Baratas Díaz, Luis Alfredo

    1996-06-01

    Full Text Available Throughout second half of 18th century was constituted a scientific institutions centre around the “Paseo del Prado” (Royal Botanical Garden, Sciences Academy, Astronomic Observatory, General Hospital,.... The development of this scientific area suffered the vicissitudes and limitations that affected to the illustrated scientific policy. In 19th century the new educational and research centers establishment was scarce and laking of clear guidelines; the various projects to build a Sciences Faculty or the Arts and Trades School limited considerably the extension of the Royal Garden. In the first third of 20th century the constructing activity would be limited to the works in the Cajal Institute (plagued by misundestanding and upsetting and some constant remodeling works in the Velasco Museum and Royal Garden.

    A lo largo de la segunda mitad del siglo XVIII se constituyó en torno al actual Paseo del Prado un importante núcleo de instituciones científicas (Real Jardín Botánico, Academia de Ciencias, Observatorio Astronómico, Hospital General,.... El desarrollo de este foco científico sufrió las vicisitudes y limitaciones que afectaron a la política científica ilustrada. En el siglo XIX el establecimiento de nuevos centros docentes en esta zona fue escaso y carente de una idea directriz; los diversos proyectos para edificar una Facultad de Ciencias o la Escuela de Artes y Oficios limitaron considerablemente la extensión del Real Jardín. En el primer tercio del siglo XX la actividad constructora se limitaría a las obras en el Instituto Cajal (plagadas de malentendidos y desajustes y unas constantes obras de remodelación en el Museo Velasco y el Jardín Botánico.

  6. Análisis del futuro marco de referencia internacional

    Science.gov (United States)

    Cionco, G. R.; Arias, E. F.

    La técnica de interferometría de muy larga línea de base (VLBI) se aplica hoy a la astrometría para el cálculo de posiciones precisas de radiofuentes extragalácticas. Por tratarse de objetos lejanos, sus movimientos propios aparentes pueden considerarse nulos; esta propiedad hace que los catálogos de radiofuentes extragalácticas VLBI constituyan la mejor materialización de un sistema de referencia celeste inercial definido cinemáticamente. La Unión Astronómica Internacional (IAU) recomendó la adopción de un nuevo sistema de referencia celeste internacional materializado por las coordenadas ecuatoriales de objetos extragalácticos observados con le técnica VLBI. Para superar la precisión astrométrica actual es necesaria una mejora en la modelización de aquellos fenómenos que pueden introducir desviaciones sistemáticas en el marco de referencia celeste. El objetivo de este trabajo es poner de manifiesto las sistematicidades presentes en los distintos marcos de referencia elaborados con el próposito de materializar el nuevo sistema de referencia celeste de la IAU. Para la comparación de los distintos marcos de referencia se propone un modelo de tres rotaciones diferenciales más un término lineal que procura absorber los efectos sistemáticos presentes en las coordenadas. Se analiza igualmente la estabilidad de la solución cuando se utilizan distintos conjuntos de objetos de definición.

  7. Looking a gift horse in the mouth: Evaluation of wide-field asteroid photometric surveys

    Science.gov (United States)

    Harris, Alan W.; Pravec, Petr; Warner, Brian D.

    2012-09-01

    It has recently become possible to do a photometric survey of many asteroids at once, rather than observing single asteroids one (or occasionally a couple) at a time. We evaluate two such surveys. Dermawan et al. (Dermawan et al. [2011]. Publ. Astron. Soc. Jpn. 63, S555-S576) observed one night on the Subaru 8.2 m telescope, and Masiero et al. (Masiero, J., Jedicke, R., Durech, J., Gwen, S., Denneau, L., Larsen, J. [2009]. Icarus 204, 145-171) observed six nights over 2 weeks with the 3.6 m CFHT. Dermawan claimed 83 rotation periods from 127 detected asteroids; Masiero et al. claimed 218 rotation periods from 828 detections. Both teams claim a number of super-fast rotators (P differs from like-sized NEAs, that there are larger super-fast rotators (monolithic asteroids) in the main belt than among NEAs. Here we evaluate these survey results, applying the same criteria for reliability of results that we apply to all results listed in our Lightcurve Database (Warner, B.D., Harris, A.W., Pravec, P. [2009a]. Icarus 202, 134-146). In doing so, we assigned reliability estimates judged sufficient for inclusion in statistical studies for only 27 out of 83 (33%) periods claimed by Dermawan, and only 87 out of 218 (40%) periods reported by Masiero et al.; none of the super-fast rotators larger than about 250 m diameter claimed by either survey received a reliability rating judged sufficient for analysis. We find no reliable basis for the claim of different rotation properties between main belt and near-Earth asteroids. Our analysis presents a cautionary message for future surveys.

  8. THE BREAKDOWN OF CLASSICAL GRAVITY?

    Directory of Open Access Journals (Sweden)

    M. A. Jiménez

    2014-01-01

    Full Text Available Bajo el supuesto de que la ley de la gravedad de Newton y la Relatividad General (RG son v ́alidas a todas las escalas, surge la hip ́otesis de la existencia de materia oscura para poder explicar l a din ́amica de los sistemas astron ́omicos a escalas gal ́acticas y extragal ́acticas. Otra posibili dad, que no involucra la existencia de ning ́un componente ex ́otico, es modificar la ley de la gravedad a escalas donde la aceleraci ́on es menor que a 0 = 1 . 2 × 10 − 8 cm s − 2 . Las ́orbitas de estrellas binarias abiertas nos ofrecen un experimento decisivo en este debate. Para sistemas binarios la aceleraci ́on cae por debajo de a 0 a separaciones mayores que 7000 au, en este punto las teor ́ıas de gravedad modificada predicen velocidades constantes que no dependen de la separaci ́on, en contraste con la tercera ley de Kepler que predice velocidades que decrecen con la ra ́ız de la separaci ́on. Real izamos este experimento con una muestra de sistemas binarios con velocidades relativas y s eparaciones mayores que 10 4 au. Obtenemos como resultado un l ́ımite superior constante para la velocidades relat ivas de las estrellas binarias abiertas independiente de la separaci ́on, en contradicci ́on con la tercera ley de Kepler y en acuerdo con lo predicho por las teor ́ıas de gravedad modificada.

  9. Marriage of Electromagnetism and Gravity in an Extended Space Model and Astrophysical Phenomena

    Science.gov (United States)

    Andreev, V. A.; Tsipenyuk, D. Yu.

    2013-09-01

    The generalization of Einstein's special theory of relativity (SRT) is proposed. In this model the possibility of unification of scalar gravity and electromagnetism into a single unified field is considered. Formally, the generalization of the SRT is that instead of (1+3)-dimensional Minkowski space the (1+4)-dimensional extension G is considered. As a fifth additional coordinate the interval S is used. This value is saved under the usual Lorentz transformations in Minkowski space M, but it changes when the transformations in the extended space G are used. We call this model the extended space model (ESM). From a physical point of view our expansion means that processes in which the rest mass of the particles changes are acceptable now. If the rest mass of a particle does not change and the physical quantities do not depend on an additional variable S, then the electromagnetic and gravitational fields exist independently of each other. But if the rest mass is variable and there is a dependence on S, then these two fields are combined into a single unified field. In the extended space model a photon can have a nonzero mass and this mass can be either positive or negative. The gravitational effects such as the speed of escape, gravitational red shift and detection of light can be analyzed in the frame of the extended space model. In this model all these gravitational effects can be found algebraically by the rotations in the (1+4) dimensional space. Now it becomes possible to predict some future results of visible size of supermassive objects in our Universe due to new stage of experimental astronomy development in the RadioAstron Project and analyze phenomena is an explosion of the star V838 Mon.

  10. Very High Resolution Studies of Micrometeors Using the Arecibo 430 MHz Radar

    Science.gov (United States)

    Mathews, J. D.; Meisel, D. D.; Hunter, K. P.; Getman, V. S.; Zhou, Q.

    1997-03-01

    We present measured and inferred properties of a possible new class of "sporadic" micrometeors discovered during 18 January 1995 observations made using the very sensitive 430 MHz radar system located at Arecibo Observatory in Puerto Rico. Over 200 of these objects were observed in a 2-hr period near sunrise. The average speed was about 55 km/sec in a range of 45-63 km/sec. Approximately two-thirds of the observed trajectories were apparently nearly parallel with the vertical beam and occurred on the 93-102 km height interval. The observed occurrence rate of these meteor returns combined with the size the Arecibo beam points to a meteor flux corresponding—in the "classical" view—to ˜15th magnitude micrometeors. This information along with observed deceleration rates and radar scattering cross-sections of order 10 -8m 2, leads us to conclude that the majority of the meteors observed appear to be of order 1 μg in mass. The depth of atmospheric penetration and inferred perihelia, the majority of which lie mostly within the orbits of Mercury and Venus, point to compositions of dense refractory material. Retrograde orbits that lie well out of the plane of the ecliptic combined with the modeled effects of radiation pressure induced orbit decay suggest that these particles—with no obvious parent body—originated in the outer reaches of the solar system and that they may even be primordial in origin. It is suggested that most if not all of these particles are associated with the North Apex "source" of sporadic meteors reported by Jones and Brown (1993, Mon. Not. R. Astron. Soc.265, 524-532). Additionally, several possible radar scattering mechanisms are discussed, none of which seem completely satisfactory.

  11. Short-period comet production in close encounters with Jupiter

    International Nuclear Information System (INIS)

    A method for calculating the resultant probability distributions of orbital elements for a small body (a comet, asteroid or meteoroid) after a gravitational encounter with a planet is described. This technique incorporates the frequency of such encounters so that the chance of attaining a certain new orbit per unit time is derived. The use of this technique is then illustrated by considering the effect of Jupiter upon the orbits of near-parabolic comets with perihelia near that planet (q=5.2 AU) and in ther inner solar system (q=1.0 AU), with prograde (i=10 deg) and retrograde (i=170 deg) paths. As indicated by previous authors the prograde comets are more easily captured into short-period (P<20 yr) and intermediate-period (20< P<200 yr) orbits; however, in contradiction to most previous work but in agreement with the results of Stagg and Bailey (submitted to Mon. Not. R. Astron. Soc.) it is found that the comets with smaller perihelia, rather than those with perihelia near Jupiter, have higher capture probabilities. This is apparently due to the fact that a small deflection only is needed to sufficiently decelerate a comet onto a smaller orbit if it makes a near-perpendicular crossing of Jupiter's path, whereas a larger deflection (to achieve a large orbital change) is needed if the paths are near-parallel. With comparatively modest amounts of computer time this method may be used to calculate the relative capture probabilities as a function of i and q for all values of interest, and is thus a useful precursor to integrations following orbital evolution, since it indicates the most likely avenues whereby shorter-period comets are derived from the near-parabolic flux. 83 refs., figs., 4 tabs

  12. VESPA: Developing the Planetary Science Virtual Observatory in H2020

    Science.gov (United States)

    Erard, S.; Cecconi, B.; Le Sidaner, P.; Capria, M. T.; Rossi, A. P.; Schmitt, B.; Andre, N.; Vandaele, A. C.; Scherf, M.; Hueso, R.; Maattanen, A. E.; Thuillot, W.; Achilleos, N.; Marmo, C.; Santolik, O.; Benson, K.

    2015-12-01

    In the frame of the Europlanet-RI program, a prototype Virtual Observatory dedicated to Planetary Science has been set up. Most of the activity was dedicated to the definition of standards to handle data in this field. The aim was to facilitate searches in big archives as well as sparse databases, to make on-line data access and visualization possible, and to allow small data providers to make their data available in an interoperable environment with minimum effort. This system makes intensive use of studies and developments led in Astronomy (IVOA), Solar Science (HELIO), and space archive services (IPDA). A general standard has been devised to handle the specific complexity of Planetary Science, e.g. in terms of measurement types and coordinate frames [1]. A procedure has been identified to install small data services, and several hands-on sessions have been organized already. A specific client (VESPA) has been developed at VO-Paris (http://vespa.obspm.fr), using a resolver for target names. Selected data can be sent to VO visualization tools such as TOPCAT or Aladin though the SAMP protocol. The Europlanet H2020 program started in Sept 2015 will provide support to new data services in Europe (30 to 50 expected), and focus on the improvement of the infrastructure. Future steps will include the development of a connection between the VO world and GIS tools, and integration of heliophysics, planetary plasma and reference spectroscopic data. The Europlanet H2020 project is funded by the European Commission under the H2020 Program, grant 654208. [1] Erard et al Astron & Comp 2014

  13. OPTICAL SPECTROSCOPIC OBSERVATIONS OF GAMMA-RAY BLAZAR CANDIDATES. V. TNG, KPNO, AND OAN OBSERVATIONS OF BLAZAR CANDIDATES OF UNCERTAIN TYPE IN THE NORTHERN HEMISPHERE

    Energy Technology Data Exchange (ETDEWEB)

    Álvarez Crespo, N.; Massaro, F. [Dipartimento di Fisica, Università degli Studi di Torino, via Pietro Giuria 1, I-10125 Torino (Italy); Masetti, N. [INAF—Istituto di Astrofisica Spaziale e Fisica Cosmica di Bologna, via Gobetti 101, I-40129, Bologna (Italy); Ricci, F.; La Franca, F. [Dipartimento di Matematica e Fisica, Università Roma Tre, via della Vasca Navale 84, I-00146, Roma (Italy); Landoni, M. [INAF-Osservatorio Astronomico di Brera, Via Emilio Bianchi 46, I-23807 Merate (Italy); Patiño-Álvarez, V.; Chavushyan, V.; Torrealba, J. [Instituto Nacional de Astrofisica, Óptica y Electrónica, Apartado Postal 51-216, 72000 Puebla, México (Mexico); D’Abrusco, R.; Paggi, A.; Smith, Howard A. [Harvard—Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 (United States); Jiménez-Bailón, E. [Instituto de Astronomía, Universidad Nacional Autónoma de México, Apdo. Postal 877, Ensenada, 22800 Baja California, México (Mexico); Latronico, L. [Istituto Nazionale di Fisica Nucleare, Sezione di Torino, I-10125 Torino (Italy); Tosti, G. [Dipartimento di Fisica, Università degli Studi di Perugia, I-06123 Perugia (Italy)

    2016-02-15

    The extragalactic γ-ray sky is dominated by emission from blazars, a peculiar class of active galactic nuclei. Many of the γ-ray sources included in the Fermi-Large Area Telescope Third Source catalog (3FGL) are classified as blazar candidates of uncertain type (BCUs) because there are no optical spectra available in the literature to confirm their nature. In 2013, we started a spectroscopic campaign to look for the optical counterparts of the BCUs and of the unidentified γ-ray sources to confirm their blazar nature. Whenever possible we also determine their redshifts. Here, we present the results of the observations carried out in the northern hemisphere in 2013 and 2014 at the Telescopio Nazionale Galileo, Kitt Peak National Observatory, and Observatorio Astronómico Nacional in San Pedro Mártir. In this paper, we describe the optical spectra of 25 sources. We confirmed that all of the 15 BCUs observed in our campaign and included in our sample are blazars and we estimated the redshifts for three of them. In addition, we present the spectra for three sources classified as BL Lacs in the literature but with no optical spectra available to date. We found that one of them is a quasar (QSO) at a redshift of z = 0.208 and the other two are BL Lacs. Moreover, we also present seven new spectra for known blazars listed in the Roma-BZCAT that have an uncertain redshift or are classified as BL Lac candidates. We found that one of them, 5BZB J0724+2621, is a “changing look” blazar. According to the spectrum available in the literature, it was classified as a BL Lac, but in our observation we clearly detected a broad emission line that led us to classify this source as a QSO at z = 1.17.

  14. OPTICAL SPECTROSCOPIC OBSERVATIONS OF GAMMA-RAY BLAZAR CANDIDATES. VI. FURTHER OBSERVATIONS FROM TNG, WHT, OAN, SOAR, AND MAGELLAN TELESCOPES

    Energy Technology Data Exchange (ETDEWEB)

    Álvarez Crespo, N.; Massaro, F. [Dipartimento di Fisica, Università degli Studi di Torino, via Pietro Giuria 1, I-10125 Torino (Italy); Milisavljevic, D.; Paggi, A.; Smith, Howard A. [Harvard—Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Landoni, M. [INAF-Osservatorio Astronomico di Brera, Via Emilio Bianchi 46, I-23807 Merate (Italy); Chavushyan, V.; Patiño-Álvarez, V. [Instituto Nacional de Astrofísica, Óptica y Electrónica, Apartado Postal 51-216, 72000 Puebla, México (Mexico); Masetti, N. [INAF—Istituto di Astrofisica Spaziale e Fisica Cosmica di Bologna, via Gobetti 101, I-40129, Bologna (Italy); Jiménez-Bailón, E. [Instituto de Astronomía, Universidad Nacional Autónoma de México, Apdo. Postal 877, Ensenada, 22800 Baja California, México (Mexico); Strader, J.; Chomiuk, L. [Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States); Katagiri, H.; Kagaya, M. [College of Science, Ibaraki University, 2-1-1, Bunkyo, Mito 310-8512 (Japan); Cheung, C. C. [Space Science Division, Naval Research Laboratory, Washington, DC 20375 (United States); D’Abrusco, R. [Department of Physical Sciences, University of Napoli Federico II, via Cinthia 9, I-80126 Napoli (Italy); Ricci, F.; La Franca, F. [Dipartimento di Matematica e Fisica, Università Roma Tre, via della Vasca Navale 84, I-00146, Roma (Italy); and others

    2016-04-15

    Blazars, one of the most extreme classes of active galaxies, constitute so far the largest known population of γ-ray sources, and their number is continuously growing in the Fermi catalogs. However, in the latest release of the Fermi catalog there is still a large fraction of sources that are classified as blazar candidates of uncertain type (BCUs) for which optical spectroscopic observations are necessary to confirm their nature and their associations. In addition, about one-third of the γ-ray point sources listed in the Third Fermi-LAT Source Catalog (3FGL) are still unassociated and lacking an assigned lower-energy counterpart. Since 2012 we have been carrying out an optical spectroscopic campaign to observe blazar candidates to confirm their nature. In this paper, the sixth of the series, we present optical spectroscopic observations for 30 γ-ray blazar candidates from different observing programs we carried out with the Telescopio Nazionale Galileo, William Herschel Telescope, Observatorio Astronómico Nacional, Southern Astrophysical Research Telescope, and Magellan Telescopes. We found that 21 out of 30 sources investigated are BL Lac objects, while the remaining targets are classified as flat-spectrum radio quasars showing the typical broad emission lines of normal quasi-stellar objects. We conclude that our selection of γ-ray blazar candidates based on their multifrequency properties continues to be a successful way to discover potential low-energy counterparts of the Fermi unidentified gamma-ray sources and to confirm the nature of BCUs.

  15. The Lyman alpha reference sample. VII. Spatially resolved Hα kinematics

    Science.gov (United States)

    Herenz, Edmund Christian; Gruyters, Pieter; Orlitova, Ivana; Hayes, Matthew; Östlin, Göran; Cannon, John M.; Roth, Martin M.; Bik, Arjan; Pardy, Stephen; Otí-Floranes, Héctor; Mas-Hesse, J. Miguel; Adamo, Angela; Atek, Hakim; Duval, Florent; Guaita, Lucia; Kunth, Daniel; Laursen, Peter; Melinder, Jens; Puschnig, Johannes; Rivera-Thorsen, Thøger E.; Schaerer, Daniel; Verhamme, Anne

    2016-03-01

    We present integral field spectroscopic observations with the Potsdam Multi-Aperture Spectrophotometer of all 14 galaxies in the z ~ 0.1 Lyman Alpha Reference Sample (LARS). We produce 2D line-of-sight velocity maps and velocity dispersion maps from the Balmer α (Hα) emission in our data cubes. These maps trace the spectral and spatial properties of the LARS galaxies' intrinsic Lyα radiation field. We show our kinematic maps that are spatially registered onto the Hubble Space Telescope Hα and Lyman α (Lyα) images. We can conjecture a causal connection between spatially resolved Hα kinematics and Lyα photometry for individual galaxies, however, no general trend can be established for the whole sample. Furthermore, we compute the intrinsic velocity dispersion σ0, the shearing velocity vshear, and the vshear/σ0 ratio from our kinematic maps. In general LARS galaxies are characterised by high intrinsic velocity dispersions (54 km s-1 median) and low shearing velocities (65 km s-1 median). The vshear/σ0 values range from 0.5 to 3.2 with an average of 1.5. It is noteworthy that five galaxies of the sample are dispersion-dominated systems with vshear/σ0 1. Our result indicates that turbulence in actively star-forming systems is causally connected to interstellar medium conditions that favour an escape of Lyα radiation. Based on observations collected at the Centro Astronómico Hispano Alemán (CAHA) at Calar Alto, operated jointly by the Max-Planck Institut für Astronomie and the Instituto de Astrofísica de Andalucía (CSIC).The reduced data cubes (FITS files) are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/587/A78

  16. Orbital Monitoring of the AstraLux Large M-dwarf Multiplicity Sample

    Science.gov (United States)

    Janson, Markus; Bergfors, Carolina; Brandner, Wolfgang; Bonnefoy, Mickaël; Schlieder, Joshua; Köhler, Rainer; Hormuth, Felix; Henning, Thomas; Hippler, Stefan

    2014-10-01

    Orbital monitoring of M-type binaries is essential for constraining their fundamental properties. This is particularly useful in young systems, where the extended pre-main-sequence evolution can allow for precise isochronal dating. Here, we present the continued astrometric monitoring of the more than 200 binaries of the AstraLux Large Multiplicity Survey, building both on our previous work, archival data, and new astrometric data spanning the range of 2010-2012. The sample is very young overall—all included stars have known X-ray emission, and a significant fraction (18%) of them have recently also been identified as members of young moving groups in the solar neighborhood. We identify ~30 targets that both have indications of being young and for which an orbit either has been closed or appears possible to close in a reasonable time frame (a few years to a few decades). One of these cases, GJ 4326, is, however, identified as probably being substantially older than has been implied from its apparent moving group membership, based on astrometric and isochronal arguments. With further astrometric monitoring, these targets will provide a set of empirical isochrones, against which theoretical isochrones can be calibrated, and which can be used to evaluate the precise ages of nearby young moving groups. Based on observations collected at the European Southern Observatory, Chile, under observing programs 081.C-0314(A), 082.C-0053(A), and 084.C-0812(A), and on observations collected at the Centro Astronómico Hispano Alemán (CAHA) at Calar Alto, operated jointly by the Max-Planck Institute for Astronomy and the Instituto de Astrofísica de Andalucía (CSIC).

  17. Searching for New Yellow Symbiotic Stars: Positive Identification of StHα63

    Science.gov (United States)

    Baella, N. O.; Pereira, C. B.; Miranda, L. F.; Alvarez-Candal, A.

    2016-04-01

    Yellow symbiotic stars are useful targets for probing whether mass transfer has happened in their binary systems. However, the number of known yellow symbiotic stars is very scarce. We report spectroscopic observations of five candidate yellow symbiotic stars that were selected by their positions in the 2MASS (J - H) versus (H - Ks) diagram and which were included in some emission-line catalogs. Among the five candidates, only StHα63 is identified as a new yellow symbiotic star because of its spectrum and its position in the [TiO]1-[TiO]2 diagram, which indicates a K4-K6 spectral type. In addition, the derived electron density (˜108.4 cm-3) and several emission-line intensity ratios provide further support for that classification. The other four candidates are rejected as symbiotic stars because three of them actually do not show emission lines and the fourth one only Balmer emission lines. We also found that the WISE W3-W4 index clearly separates normal K-giants from yellow symbiotic stars and therefore can be used as an additional tool for selecting candidate yellow symbiotic stars. Based on observations collected at the Centro Astronómico Hispano-Alemán, Calar Alto, jointly operated by the Max-Planck-Institut für Astronomie (Heidelberg) and the Instituto de Astrofísica de Andalucía (CSIC), and at the 4.1 m telescope at Cerro Pachón Observatory, Chile.

  18. The AstraLux Multiplicity Survey: Extension to Late M-dwarfs

    Science.gov (United States)

    Janson, Markus; Bergfors, Carolina; Brandner, Wolfgang; Kudryavtseva, Natalia; Hormuth, Felix; Hippler, Stefan; Henning, Thomas

    2014-07-01

    The distribution of multiplicity among low-mass stars is a key issue to understanding the formation of stars and brown dwarfs, and recent surveys have yielded large enough samples of nearby low-mass stars to study this issue statistically to good accuracy. Previously, we have presented a multiplicity study of ~700 early/mid M-type stars observed with the AstraLux high-resolution Lucky Imaging cameras. Here, we extend the study of multiplicity in M-type stars through studying 286 nearby mid/late M-type stars, bridging the gap between our previous study and multiplicity studies of brown dwarfs. Most of the targets have been observed more than once, allowing us to assess common proper motion to confirm companionship. We detect 68 confirmed or probable companions in 66 systems, of which 41 were previously undiscovered. Detections are made down to the resolution limit of ~100 mas of the instrument. The raw multiplicity in the AstraLux sensitivity range is 17.9%, leading to a total multiplicity fraction of 21%-27% depending on the mass ratio distribution, which is consistent with being flat down to mass ratios of ~0.4, but cannot be stringently constrained below this value. The semi-major axis distribution is well represented by a log-normal function with μa = 0.78 and σa = 0.47, which is narrower and peaked at smaller separations than for a Sun-like sample. This is consistent with a steady decrease in average semi-major axis from the highest-mass binary stars to the brown dwarf binaries. Based on observations collected at the Centro Astronómico Hispano Alemán (CAHA) at Calar Alto, operated jointly by the Max-Planck Institute for Astronomy and the Instituto de Astrofísica de Andalucía (CSIC).

  19. OV-Wav: um novo pacote para análise multiescalar em astronomia

    Science.gov (United States)

    Pereira, D. N. E.; Rabaça, C. R.

    2003-08-01

    Wavelets e outras formas de análise multiescalar têm sido amplamente empregadas em diversas áreas do conhecimento, sendo reconhecidamente superiores a técnicas mais tradicionais, como as análises de Fourier e de Gabor, em certas aplicações. Embora a teoria dos wavelets tenha começado a ser elaborada há quase trinta anos, seu impacto no estudo de imagens astronômicas tem sido pequeno até bem recentemente. Apresentamos um conjunto de programas desenvolvidos ao longo dos últimos três anos no Observatório do Valongo/UFRJ que possibilitam aplicar essa poderosa ferramenta a problemas comuns em astronomia, como a remoção de ruído, a detecção hierárquica de fontes e a modelagem de objetos com perfis de brilho arbitrários em condições não ideais. Este pacote, desenvolvido para execução em plataforma IDL, teve sua primeira versão concluída recentemente e está sendo disponibilizado à comunidade científica de forma aberta. Mostramos também resultados de testes controlados ao quais submetemos os programas, com a sua aplicação a imagens artificiais, com resultados satisfatórios. Algumas aplicações astrofísicas foram estudadas com o uso do pacote, em caráter experimental, incluindo a análise da componente de luz difusa em grupos compactos de galáxias de Hickson e o estudo de subestruturas de nebulosas planetárias no espaço multiescalar.

  20. Newly Identified Rydberg Emission Lines in Novae

    Science.gov (United States)

    Lynch, David K.; Rudy, R. J.; Bernstein, L. S.

    2008-09-01

    Newly Identified Rydberg Emission Lines in Novae David K. Lynch, Richard. J. Rudy (The Aerospace Corporation) & Lawrence S. Bernstein (Spectral Sciences, Inc.) Novae spectra in the near infrared frequently show a set of six emission lines that have not been positively identified (Williams, Longmore, & Geballe 1996, MNRAS, 279, 804; Lynch et al. 2001, AJ, 122, 2013; Rudy et al. 2002 ApJ, 573, 794; Lynch et al. 2004 Astron. J. 127, 1089-1097). These lines are at 0.8926, 1.1114, 1.1901, 1.5545, 2.0996 and 2.425 µm ± 0.005 µm. Krautter et al. (1984 A&A 137, 304) suggested that three of the lines were due to rydberg (hydrogenic) transitions in an unspecified atomic species that was in the 4th or 5th ionization stage (core charge = 4 & 5). We believe that Krautter et al.'s explanation is correct based on 4 additional lines that we have identified in the visible and near infrared spectrum of V723 Cassiopeiae. The observed Rydberg lines appear to originate from high angular momentum states with negligible quantum defects. The species cannot be determined with any certainty because in rydberg states, the outer electron sees a nucleus shielded by the inner electrons and together the inner atom appears to have a charge of +1, like hydrogen. As a result, the atom looks hydrogenic and species such as CV, NV, OV, MgV, SiV, etc. have their rydberg transitions at very similar wavelengths. All the lines represent permitted transitions, most likely formed by recombination. Atoms with core charges 4, 5 & 6 are rarely seen in the astrophysical environment because an extremely hot radiation field is necessary to ionize them. Thermonuclear runaways on the surface of a white dwarf can reach millions of degrees K, and thus there are enough X-ray photons available to achieve the necessary high ionization levels.

  1. On 17 22 January 2005 Events in Space Weather

    Science.gov (United States)

    Dorotovič, I.; Kudela, K.; Lorenc, M.; Rybanský, M.

    2008-08-01

    This contribution is a follow-up to the recent paper of Kuznetsov et al. ( Contrib. Astron. Obs. Skalnaté Pleso 36, 85, 2006) on the ground level enhancement (GLE) on 20 January 2005. We focused on a study of Forbush decrease (FD) of 17 18 and 21 22 January 2005, respectively. The data from the neutron monitor at Lomnický Štít (1 min counts) and from the Geomagnetic Observatory in Hurbanovo, both in Slovakia, were used as the basis for our investigation. The data on magnetic field and solar wind from GOES 10 and 12, SOHO-CELIAS, ACE and WIND satellites were used for better understanding of the global evolution of the event. The magnetic field is transformed to the RTN (Radial Tangential Normal) system where only the disturbed part of the field is compared, i.e., daily variations and a constant part are subtracted. The field reduction method is described. Our results are temporal vector diagrams of variation of all parameters at all positions from where we used the data. The amplitudes of | B| exceed 100 nT and variations during the arrival of the wavefront of CME take place simultaneously at the ground-based station and at GOES satellites. The character of the variations is as if there would be regions with the dominant electric charge of opposite signs, or electric currents with different orientations in the CME. On the basis of the values v p and n p and using certain assumptions we determined the mass of CME on 17 January and 21 January, respectively, of 1012 kg. A decrease of the cosmic ray level runs suddenly (during 10 minutes), starting, however, about two hours after a sudden change of the magnetic field.

  2. Long-Term Stability of Planets in the Alpha Centauri System

    Science.gov (United States)

    Lissauer, Jack J.; Quarles, Billy L.

    2016-10-01

    The alpha Centauri star system contains the Solar Systems closest stellar neighbors. If an earthlike planet is present in the system, it could in principle be detected using a small space-based telescope (Belikov et al. 2105, Proc. SPIE 9605, 960518). The alpha Centauri system is billions of years old, so planets are only expected to be found in regions where their orbits are long-lived. We evaluate the extent of the regions within the alpha Centauri AB star system where small planets are able to orbit for billion-year timescales, and we map the positions in the sky plane where planets on stable orbits about either stellar component may appear. We confirm the qualitative results of Wiegert & Holman (Astron. J. 113, 1445, 1997) regarding the approximate size of the regions of stable orbits of a single planet, which are larger for retrograde orbits relative to the binary than for prograde orbits. Additionally, we find that mean motion resonances with the binary orbit leave an imprint on the limits of orbital stability, and the effects of the Lidov-Kozai mechanism are also readily apparent. Because the binary companion induces a forced eccentricity upon the orbits of planets in orbit around either star, appropriately-phased circumstellar orbits with small initial eccentricities are stable to somewhat larger initial semimajor axes than are initially circular orbits and the initial mean anomaly of planets is a factor in determining stability. Our results can guide observers designing instrumentation and search strategies to attempt to discover planets orbiting the nearest sunlike stars.

  3. Resistance of Wheat Accessions to the English Grain Aphid Sitobion avenae.

    Science.gov (United States)

    Hu, Xiang-Shun; Liu, Ying-Jie; Wang, Yu-Han; Wang, Zhe; Yu, Xin-Lin; Wang, Bo; Zhang, Gai-Sheng; Liu, Xiao-Feng; Hu, Zu-Qing; Zhao, Hui-Yan; Liu, Tong-Xian

    2016-01-01

    The English grain aphid, Sitobion avenae, is a major pest species of wheat crops; however, certain varieties may have stronger resistance to infestation than others. Here, we investigated 3 classical resistance mechanisms (antixenosis, antibiosis, and tolerance) by 14 wheat varieties/lines to S. avenae under laboratory and field conditions. Under laboratory conditions, alatae given the choice between 2 wheat varieties, strongly discriminated against certain varieties. Specifically, the 'Amigo' variety had the lowest palatability to S. avenae alatae of all varieties. 'Tm' (Triticum monococcum), 'Astron,' 'Xanthus,' 'Ww2730,' and 'Batis' varieties also had lower palatability than other varieties. Thus, these accessions may use antibiosis as the resistant mechanism. In contrast, under field conditions, there were no significant differences in the number of alatae detected on the 14 wheat varieties. One synthetic line (98-10-30, a cross between of Triticum aestivum (var. Chris) and Triticum turgidum (var. durum) hybridization) had low aphid numbers but high yield loss, indicating that it has high antibiosis, but poor tolerance. In comparison, 'Amigo,' 'Xiaoyan22,' and some '186Tm' samples had high aphid numbers but low yield loss rates, indicating they have low antibiosis, but good tolerance. Aphid population size and wheat yield loss rates greatly varied in different fields and years for '98-10-35,' 'Xiaoyan22,' 'Tp,' 'Tam200,' 'PI high,' and other '186Tm' samples, which were hybrid offspring of T. aestivum and wheat related species. Thus, these germplasm should be considered for use in future studies. Overall, S. avenae is best adapted to 'Xinong1376,' because it was the most palatable variety, with the greatest yield loss rates of all 14 wheat varieties. However, individual varieties/lines influenced aphid populations differently in different years. Therefore, we strongly recommend a combination of laboratory and long-term field experiments in targeted planting

  4. Development of Lumped Element Kinetic Inductance Detectors for the W-Band

    Science.gov (United States)

    Paiella, A.; Coppolecchia, A.; Castellano, M. G.; Colantoni, I.; Cruciani, A.; D'Addabbo, A.; de Bernardis, P.; Masi, S.; Presta, G.

    2016-07-01

    We are developing a lumped element kinetic inductance detector (LEKID) array which can operate in the W-band (75-110 GHz) in order to perform ground-based cosmic microwave background (CMB) and mm-wave astronomical observations. The W-band is close to optimal in terms of contamination of the CMB from Galactic synchrotron, free-free, and thermal interstellar dust. In this band, the atmosphere has very good transparency, allowing interesting ground-based observations with large (>30 m) telescopes, achieving high angular resolution (work we describe the startup measurements devoted to the optimization of a W-band camera/spectrometer prototype for large aperture telescopes like the 64-m Sardinia Radio Telescope. In the process of selecting the best superconducting film for the LEKID, we characterized a 40-nm-thick aluminum 2-pixel array. We measured the minimum frequency which can break CPs (i.e., hν =2Δ ( T_c) =3.5 k_BT_c) obtaining ν =95.5 GHz, which corresponds to a critical temperature of 1.31 K. This is not suitable to cover the entire W-band. For an 80-nm layer the minimum frequency decreases to 93.2 GHz, which corresponds to a critical temperature of 1.28 K; this value is still suboptimal for W-band operation. Further increase of the Al film thickness results in bad performance of the detector. We have thus considered a Titanium-Aluminum bi-layer [10-nm-thick Ti + 25-nm-thick Al, already tested in other laboratories (Catalano et al. in Astron Astrophys 580:A15, 2015)], for which we measured a critical temperature of 820 mK and a cut-on frequency of 65 GHz, so this solution allows operation in the entire W-band.

  5. El Sistema de Referencia Celeste convencional de la IAU

    Science.gov (United States)

    Arias, E. F.

    La Unión Astronómica Internacional (IAU) recomendó la adopción de un nuevo sistema de referencia celeste baricéntrico cuyo plano fundamental y origen de ascensiones rectas estén próximos, respectivamente, al ecuador y equinoccio dinámicos J2000.0. El nuevo sistema de referencia estará materializado por las posiciones J2000.0 de radiofuentes extragalácticas determinadas con la técnica de interferometría de larga línea de base (VLBI). El Working Group on Reference Frames de la IAU (WGRF) decidió adoptar (Grasse, 1995) al sistema de referencia celeste extragaláctico del Servicio Internacional de la Rotación Terrestre (IERS) como futuro sistema de referencia celeste convencional bajo el nombre International Celestial Reference System (ICRS) y encomendó su mantenimiento futuro al IERS. El marco de referencia que materializará al ICRS contiene posiciones precisas J2000.0 de más de 600 radiofuentes extragalácticas. Las coordenadas fueron ajustadas en una única solución VLBI en la cual se incluyeron todas las observaciones realizadas hasta octubre de 1995 con la técnica de adquisición de datos VLBI Mark III. Para minimizar los errores sistemáticos que pueden afectar la calidad del marco de referencia se introdujeron mejoras sustanciales en la modelización y en la selección de datos. Un subconjunto de objetos del marco de referencia se utilizó para referir las posiciones estelares determinadas con el satélite astrométrico Hipparcos al ICRS.

  6. Analysis of selected Kepler Mission planetary light curves

    Science.gov (United States)

    Rhodes, M. D.; Budding, E.

    2014-06-01

    We have modified the graphical user interfaced close binary system analysis program CurveFit to the form WinKepler and applied it to 16 representative planetary candidate light curves found in the NASA Exoplanet Archive (NEA) at the Caltech website http://exoplanetarchive.ipac.caltech.edu, with an aim to compare different analytical approaches. WinKepler has parameter options for a realistic physical model, including gravity-brightening and structural parameters derived from the relevant Radau equation. We tested our best-fitting parameter-sets for formal determinacy and adequacy. A primary aim is to compare our parameters with those listed in the NEA. Although there are trends of agreement, small differences in the main parameter values are found in some cases, and there may be some relative bias towards a 90∘ value for the NEA inclinations. These are assessed against realistic error estimates. Photometric variability from causes other than planetary transits affects at least 6 of the data-sets studied; with small pulsational behaviour found in 3 of those. For the false positive KOI 4.01, we found that the eclipses could be modelled by a faint background classical Algol as effectively as by a transiting exoplanet. Our empirical checks of limb-darkening, in the cases of KOI 1.01 and 12.01, revealed that the assigned stellar temperatures are probably incorrect. For KOI 13.01, our empirical mass-ratio differs by about 7 % from that of Mislis and Hodgkin (Mon. Not. R. Astron. Soc. 422:1512, 2012), who neglected structural effects and higher order terms in the tidal distortion. Such detailed parameter evaluation, additional to the usual main geometric ones, provides an additional objective for this work.

  7. Realistic exact solution for the exterior field of a rotating neutron star

    Science.gov (United States)

    Pachón, Leonardo A.; Rueda, Jorge A.; Sanabria-Gómez, José D.

    2006-05-01

    A new six-parametric, axisymmetric, and asymptotically flat exact solution of Einstein-Maxwell field equations having reflection symmetry is presented. It has arbitrary physical parameters of mass, angular momentum, mass-quadrupole moment, current octupole moment, electric charge, and magnetic dipole, so it can represent the exterior field of a rotating, deformed, magnetized, and charged object; some properties of the closed-form analytic solution such as its multipolar structure, electromagnetic fields, and singularities are also presented. In the vacuum case, this analytic solution is matched to some numerical interior solutions representing neutron stars, calculated by Berti and Stergioulas [E. Berti and N. Stergioulas, Mon. Not. R. Astron. Soc.MNRAA40035-8711 350, 1416 (2004)10.1111/j.1365-2966.2004.07740.x], imposing that the multipole moments be the same. As an independent test of accuracy of the solution to describe exterior fields of neutron stars, we present an extensive comparison of the radii of innermost stable circular orbits (ISCOs) obtained from the Berti and Stergioulas numerical solutions, the Kerr solution [R. P. Kerr, Phys. Rev. Lett.PRLTAO0031-9007 11, 237 (1963)10.1103/PhysRevLett.11.237], the Hartle and Thorne solution [J. B. Hartle and K. S. Thorne, Astrophys. J.ASJOAB0004-637X 153, 807 (1968)10.1086/149707], an analytic series expansion derived by Shibata and Sasaki [M. Shibata and M. Sasaki, Phys. Rev. DPRVDAQ0556-2821 58, 104011 (1998)10.1103/PhysRevD.58.104011], and our exact solution. We found that radii of ISCOs from our solution fits better than others with realistic numerical interior solutions.

  8. Apoastron shift constraints on dark matter distribution at the Galactic Center

    Science.gov (United States)

    Zakharov, A. F.; Nucita, A. A.; de Paolis, F.; Ingrosso, G.

    2007-09-01

    The existence of dark matter (DM) at scales of a few parsecs down to ≃10-5pc around the centers of galaxies and, in particular, in the Galactic Center region has been considered in the literature. Under the assumption that such a DM clump, principally constituted by nonbaryonic matter (like weakly interacting massive particles) does exist at the center of our galaxy, the study of the γ-ray emission from the Galactic Center region allows us to constrain both the mass and the size of this DM sphere. Further constraints on the DM distribution parameters may be derived by observations of bright infrared stars around the Galactic Center. Hall and Gondolo [J. Hall and P. Gondolo, Phys. Rev. D 74, 063511 (2006)PRVDAQ0556-282110.1103/PhysRevD.74.063511] used estimates of the enclosed mass obtained in various ways and tabulated by Ghez et al. [A. M. Ghez , Astron. Nachr. 324, 527 (2003); ASNAAN0004-633710.1002/asna.200385103A. M. Ghez , Astrophys. J.ASJOAB0004-637X 620, 744 (2005)10.1086/427175]. Moreover, if a DM cusp does exist around the Galactic Center it could modify the trajectories of stars moving around it in a sensible way depending on the DM mass distribution. Here, we discuss the constraints that can be obtained with the orbit analysis of stars (as S2 and S16) moving inside the DM concentration with the present and next generations of large telescopes. In particular, consideration of the S2 star apoastron shift may allow improving limits on the DM mass and size.

  9. Jupiter's Synchrotron Emission Induced by the Collision of Comet Shoemaker-Levy 9

    Science.gov (United States)

    Olano, C. A.

    1999-08-01

    From July 13 to August 21, 1994, we observed Jupiter at 1420 MHz using one of the 30-m single dishes of the Instituto Argentino de Radioastronomía. After the impact of fragment G, we detected a rapid increase of the 21cm-continuum flux, which reached the maximum (≈ 20% of Jupiter's flux) at the end of the impact period. The nature of this radiation is clearly synchrotron. We interpret it in terms of a new population of relativistic electrons (≈ 2 × 1029) injected into the Jovian magnetosphere as a consequence of the impact explosions. The proposed mechanism is that the relativistic plasma was blown as magnetic clouds that flowed along the magnetic lines of force towards the jovimagnetic equator. We constructed a model in which the energies of the fresh electrons, generated within the magnetized clouds with a power law energy spectrum, were highly degraded by the comet dust grains attached to the magnetized plasma. The model can account for the spectral shape based on observations at several frequencies (de Pater et al., 1995, Science 268, 1879; Venturi et al., 1996, Astron. Astrophys. 316, 243). The energy released by the explosions under the form of relativistic electrons is of ≈ 2 × 1025 erg, which represents a fraction of about 1 3 per cent of the explosion energy. The efficiency in converting the explosion energy into the relativistic electron energy is, therefore, of the same order of magnitude as that of supernova explosions. An alternative model is considered. This gives figures for the total energy and number of relativistic electrons that are similar to the corresponding ones of the favoured model. Finally, we suggest that the behavior of the flux decay in the various observed frequencies is the result of the diffusion of electrons into the loss-cone due to the resonant scattering of the electrons by Alfven waves.

  10. Chemical Abundances of NGC 5461 and NGC 5471 Derived from Echelle Spectrophotometry

    Directory of Open Access Journals (Sweden)

    V. Luridiana

    2002-01-01

    Full Text Available Presentamos espectrofotometría de alta resolución de NGC 5461 y NGC 5471, dos regiones H II gigantes en la galaxia M101. Los datos se obtuvieron con el telescopio de 2.1 m del Observatorio Astronómico Nacional en San Pedro Mártir, Baja California. Medimos las intensidades de un conjunto de líneas de recombinación de hidrógeno y de helio, así como líneas prohibidas de un gran número de iones. Calculamos las condiciones físicas en las dos nebulosas y calculamos las abundancias químicas totales tomando en cuenta las abundancias iónicas observadas así como las no observadas; estas últimas las estimamos a partir de factores de corrección de ionización (icf `s. Para NGC 5461 los icf`s se basan en un modelo detallado de fotoionización diseñado específicamente para este objeto (Luridiana & Peimbert 2001, mientras que para NGC 5471 se obtuvieron a partir de un modelo de fotoionizacióon para NGC 2363 (Luridiana, Peimbert, & Leitherer 1999, región que muestra un grado de ionización muy semejante al de NGC 5471. Los icf s así determinados los comparamos con aquellos que se obtienen a partir de las fórmulas de Mathis & Rosa (1991. Dicha comparación muestra importantes discrepancias para algunos de los elementos incluyendo nitrógeno, neón y cloro.

  11. NEW DEVELOPMENTS IN JASTROCAM - SOFTWARE FOR ASTRONOMICAL DATA GATHERING

    Directory of Open Access Journals (Sweden)

    S. Zola

    2014-01-01

    Full Text Available Presentamos una aplicaci ́on de software llamada JAstroCam . Es un paquete de software basado en Java que est ́a siendo desarrollado en cooperaci ́on con el Observato rio Astron ́omico de la Universidad de Jagiellonia y el Observatorio de Mt. Suhora de la Universidad Pedag ́ogica , y cubre todos los aspectos de adquisici ́on de im ́agenes, incluyendo el control del hardware, monitoreo d e ambiente y ayuda a los observadores a adquirir datos cient ́ıficos de alta calidad. El motivo principal para hacer a ́un otro software m ́as es la carencia de herramientas avanzadas para la adquisici ́on de datos con CC Ds en Linux. La mayor ́ıa de los vendedores de hardware proveen drivers y aplicaciones de apoyo principal mente en el sistema operativo Windows, dejando a los usuarios de Linux con un n ́umero limitado de soluciones c ́odigo abierto, usualmente no optimizadas para astr ́onomos profesionales. En cooperaci ́on con investiga dores acad ́emicos, hemos logrado implementar una aplicaci ́on con una interfaz de usuario intuitiva adem ́as d e herramientas poderosas que realizan adquisici ́on de im ́agenes programada y an ́alisis de datos preliminar onlin e, incluyendo medidas de par ́ametros estad ́ısticos de cuadros individuales al igual que fotometr ́ıa de filtros ind ividuales y m ́ultiples. Se presentan las caracter ́ısticas actuales, las mejoras m ́as recientes en la versi ́on 3.X al ig ual que los planes de desarrollo futuro para la versi ́on 4 de JAstroCam.

  12. Contribution of astrology in medicine -- a review.

    Science.gov (United States)

    Sharma, Bhuvnesh Kumar; Prasad, P V V; Narayana, A

    2007-01-01

    Astrology is the art of predicting or determining the influence of the planets and stars on human affairs. The origin of this word is from Greek word astron, star + logos (discourse). Both Ayurveda and Astrology have established a way of life in India since time immemorial. Highly advanced knowledge related to Astrology on medicine is preserved in Indian Holy scriptures and transmitted from generation to generation. Although both Astrology and medicine were developed as a part of religion in ancient India, astrological principles related to prevention, health care and relief from illness were applied as rituals (religious ceremonies). An astrologer gives guidance for taking medicines at suitable time for the best remedy of ailments. Even the medicinal herbs were collected and used at appropriate times for their efficacy. Astrology and Ayurveda are inseparable in human life. Role of the Astrology in healthy life and pathogenesis of the disease is well known to Indians. When a physician knows etiology of the disease, he attempts to treat the disease with specific medication, diet and life style and also avoiding causative factors. In a case where a physician is unable to understand the pathogenesis of the disease and to treat, the patient depends upon Astrology. Account of good and bad deeds during this life and previous lives, their consequences of health or ill health during this life which orderly, when, what and how will be clearly known through Astrology. It gives guidelines about welfare not only to human being but also to whole creation and also indicates about calamities and their solutions as possible extent. Hence a concise astrological evaluation related to prevention, health care, diagnosis and treatment of diseases is being presented in this article.

  13. Health promotion, preventive and curative aspects of diseases in astrology.

    Science.gov (United States)

    Sharma, Bhuvnesh Kumar; Subhakta, P K J P; Narayana, A

    2007-01-01

    The whole universe is intermingling into a unit in the period of globalization. Different cultures, life-styles and sciences are co-operating with each other in this situation. World Health Organization is working towards collaborating all prevalent medical sciences for attainment of good health and family welfare for each and every individual by 2020. Astrology is a part of Indian heritage. Astrology means the art of predicting or determining the influence of the planets and stars on human affairs. The origin of this word is from Greek word astron, star + logos (discourse). The account of deeds of good and bad during the present life and previous lives, their consequences of health or ill health during this life i.e. what, when and how the things takes place will be clearly known through Astrology. Highly advanced knowledge related to Astrology on medicine is preserved in Indian scriptures and the knowledge was transmitted from generation to generation. It is also a good source for health promotion, preventive, curative and other medical aspects. Brief direction related to astrological medical aspects is also available in Ayurvedic literature (Carakasamhită, Suśrutasamhhită, Aşţăngasangraha, Aşţăngahŗdaya, Sărngadharasamhită , Băvaprakăśa etc.) Some Ayurvedic practitioners, scholars and scientists realize the need of astrological knowledge related to medicine in the present time. In ancient times physician, astrologer and purŏhita (Hindu priest) simultaneously looked after the health and family welfare of individual, families and country. Astrologer guides medication and suitable time for the better cure of ailments. Even the medicinal herbs were collected and treated at appropriate time for their efficacy. Astrology and Ayurvĕda are inseparable sciences of life. Hence, in this article, a concise astrological evaluation related to health promotion, preventive and curative aspects of Astrology is being presented.

  14. Direct Imaging discovery of a second planet candidate around the possibly transiting planet host CVSO 30

    Science.gov (United States)

    Schmidt, T. O. B.; Neuhäuser, R.; Briceño, C.; Vogt, N.; Raetz, St.; Seifahrt, A.; Ginski, C.; Mugrauer, M.; Buder, S.; Adam, C.; Hauschildt, P.; Witte, S.; Helling, Ch.; Schmitt, J. H. M. M.

    2016-09-01

    Context. Direct imaging has developed into a very successful technique for the detection of exoplanets in wide orbits, especially around young stars. Directly imaged planets can be both followed astrometrically on their orbits and observed spectroscopically and thus provide an essential tool for our understanding of the early solar system. Aims: We surveyed the 25 Ori association for direct-imaging companions. This association has an age of only few million years. Among other targets, we observed CVSO 30, which has recently been identified as the first T Tauri star found to host a transiting planet candidate. Methods: We report on photometric and spectroscopic high-contrast observations with the Very Large Telescope, the Keck telescopes, and the Calar Alto observatory. They reveal a directly imaged planet candidate close to the young M3 star CVSO 30. Results: The JHK-band photometry of the newly identified candidate is at better than 1σ consistent with late-type giants, early-T and early-M dwarfs, and free-floating planets. Other hypotheses such as galaxies can be excluded at more than 3.5σ. A lucky imaging z' photometric detection limit z' = 20.5 mag excludes early-M dwarfs and results in less than 10 MJup for CVSO 30 c if bound. We present spectroscopic observations of the wide companion that imply that the only remaining explanation for the object is that it is the first very young (ESO Telescopes at the La Silla Paranal Observatory under programme IDs 090.C-0448(A), 290.C-5018(B), 092.C-0488(A) and at the Centro Astronómico Hispano-Alemán in programme H15-2.2-002.

  15. Geotechnical study of the oan/spm

    Directory of Open Access Journals (Sweden)

    B. Sánchez

    2003-01-01

    Full Text Available El estudio de caracterizaci on geot ecnica de San Pedro M artir (SPM, Baja California, fu e realizado en 2000 por la Gerencia de Estudios de Ingenier a Civil de la Comisi on Federal de Electricidad (GEIC/CFE. El prop osito principal de los estudios geol ogicos y geot ecnicos es la caracterizaci on del terreno en uno de los posibles sitios de construcci on de un nuevo telescopio, lo cual adem as dar a idea de las caracter sticas de otros puntos en la zona del Observatorio Astron omico Nacional en San Pedro M artir (OAN/SPM. El reporte completo del estudio geot ecnico de SPM de la GEIC/CFE incluye resultados de los estudios topogr a cos, geol ogicos y geof sicos llevados a cabo en el sitio y en laboratorio. Aqu se presenta una revisi on del estudio geot ecnico y de los principales resultados. Se muestra que el subsuelo puede ser clasi cado en tres horizontes o capas principales (A, B y C. El horizonte-A est a constituido por roca descomprimida hasta profundidades de 1.3 a 3.0 m, la cual ser a necesario remover para la cimentaci on. La capa B consiste de roca fracturada con un RQD (\\rock quality designation" entre 65% y 80%, con un espesor de 10 a 12 m, y una alta capacidad de carga. Esto implica que la profundidad requerida de excavaci on para las zapatas de la cimentaci on es de 2 a 3 m, donde se alcanza un m odulo de elasticidad adecuado. El horizonte C de 13 a 22 m consiste de roca (equisto gris de caracter masivo con intrusivos gran ticos, considerablemente menos fracturada, con un RQD superior a 90%. Para las tierras ele ectricas la capa B es adecuada por su baja resistividad.

  16. Recovering Joy's Law as a Function of Solar Cycle, Hemisphere, and Longitude

    Science.gov (United States)

    McClintock, B. H.; Norton, A. A.

    2013-10-01

    Bipolar active regions in both hemispheres tend to be tilted with respect to the East-West Equator of the Sun in accordance with Joy's law, which describes the average tilt angle as a function of latitude. Mt. Wilson Observatory data from 1917 - 1985 are used to analyze the active-region tilt angle as a function of solar cycle, hemisphere, and longitude, in addition to the more common dependence on latitude. Our main results are as follows: i) We recommend a revision of Joy's law towards a weaker dependence on latitude (slope of 0.13 - 0.26) and without forcing the tilt to zero at the Equator. ii) We determine that the hemispheric mean tilt value of active regions varies with each solar cycle, although the noise from a stochastic process dominates and does not allow for a determination of the slope of Joy's law on an 11-year time scale. iii) The hemispheric difference in mean tilt angles, 1.1∘±0.27, over Cycles 16 to 21 was significant to a three- σ level, with average tilt angles in the Northern and Southern hemispheres of 4.7∘±0.26 and 3.6∘±0.27, respectively. iv) Area-weighted mean tilt angles normalized by latitude for Cycles 15 to 21 anticorrelate with cycle strength for the southern hemisphere and whole-Sun data, confirming previous results by Dasi-Espuig et al. ( Astron. Astrophys. 518, A7, 2010). The Northern Hemispheric mean tilt angles do not show a dependence on cycle strength. v) Mean tilt angles do not show a dependence on longitude for any hemisphere or cycle. In addition, the standard deviation of the mean tilt is 29 - 31∘ for all cycles and hemispheres, indicating that the scatter is due to the same consistent process even if the mean tilt angles vary.

  17. The slowly pulsating B-star 18 Pegasi: A testbed for upper main sequence stellar evolution

    Science.gov (United States)

    Irrgang, A.; Desphande, A.; Moehler, S.; Mugrauer, M.; Janousch, D.

    2016-06-01

    The predicted width of the upper main sequence in stellar evolution models depends on the empirical calibration of the convective overshooting parameter. Despite decades of discussions, its precise value is still unknown and further observational constraints are required to gauge it. Based on a photometric and preliminary asteroseismic analysis, we show that the mid B-type giant 18 Peg is one of the most evolved members of the rare class of slowly pulsating B-stars and, thus, bears tremendous potential to derive a tight lower limit for the width of the upper main sequence. In addition, 18 Peg turns out to be part of a single-lined spectroscopic binary system with an eccentric orbit that is greater than 6 years. Further spectroscopic and photometric monitoring and a sophisticated asteroseismic investigation are required to exploit the full potential of this star as a benchmark object for stellar evolution theory. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO programmes 265.C-5038(A), 069.C-0263(A), and 073.D-0024(A). Based on observations collected at the Centro Astronómico Hispano Alemán (CAHA) at Calar Alto, operated jointly by the Max-Planck Institut für Astronomie and the Instituto de Astrofísica de Andalucía (CSIC), proposals H2005-2.2-016 and H2015-3.5-008. Based on observations made with the William Herschel Telescope operated on the island of La Palma by the Isaac Newton Group in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias, proposal W15BN015. Based on observations obtained with telescopes of the University Observatory Jena, which is operated by the Astrophysical Institute of the Friedrich-Schiller-University.

  18. Structure of self-gravity wakes in Saturn's A ring as measured by Cassini CIRS

    Science.gov (United States)

    Ferrari, C.; Brooks, S.; Edgington, S.; Leyrat, C.; Pilorz, S.; Spilker, L.

    2009-01-01

    The CIRS infrared spectrometer onboard the Cassini spacecraft has scanned Saturn's A ring azimuthally from several viewing angles since its orbit insertion in 2004. A quadrupolar asymmetry has been detected in this ring at spacecraft elevations ranging between 16° to 37°. Its fractional amplitude decreases from 22% to 8% from 20° to 37° elevations. The patterns observed in two almost complete azimuthal scans at elevations 20° and 36° strongly favor the self-gravity wakes as the origin of the asymmetry. The elliptical, infinite cylinder model of Hedman et al. [Hedman, M.M., Nicholson, P.D., Salo, H., Wallis, B.D., Buratti, B.J., Baines, K.H., Brown, R.H., Clark, R.N., 2007. Astron. J. 133, 2624-2629] can reproduce the CIRS observations well. Such wakes are found to have an average height-to-spacing ratio H/λ=0.1607±0.0002, a width-over-spacing W/λ=0.3833±0.0008. Gaps between wakes, which are filled with particles, have an optical depth τ=0.1231±0.0005. The wakes mean pitch angle Φ is 70.70°±0.07°, relative to the radial direction. The comparison of ground-based visible data with CIRS observations constrains the A ring to be a monolayer. For a surface mass density of 40 g cm -2 [Tiscarino, M.S., Burns, J.A., Nicholson, P.D., Hedman, M.M., Porco, C.C., 2007. Icarus 189, 14-34], the expected spacing of wakes is λ≈60 m. Their height and width would then be H≈10 m and W≈24 m, values that match the maximum size of particles in this ring as determined from ground-based stellar occultations [French, R.G., Nicholson, P.D., 2000. Icarus 145, 502-523].

  19. Giga-year evolution of Jupiter Trojans and the asymmetry problem

    Science.gov (United States)

    Di Sisto, Romina P.; Ramos, Ximena S.; Beaugé, Cristián

    2014-11-01

    We present a series of numerical integrations of observed and fictitious Jupiter Trojan asteroids, under the gravitational effects of the four outer planets, for time-spans comparable with the age of the Solar System. From these results we calculate the escape rate from each Lagrange point, and construct dynamical maps of "permanence" time in different regions of the phase space. Fictitious asteroids in L4 and L5 show no significant difference, showing almost identical dynamical maps and escape rates. For real Trojans, however, we found that approximately 23% of the members of the leading swarm escaped after 4.5 Gyrs, while this number increased to 28.3% for L5 . This implies that the asymmetry between the two populations increases with time, indicating that it may have been smaller at the time of formation/capture of these asteroids. Nevertheless, the difference in chaotic diffusion cannot, in itself, account for the current observed asymmetry (∼40%), and must be primarily primordial and characteristic of the capture mechanism of the Trojans. Finally, we calculate new proper elements for all the numbered Trojans using the semi-analytical approach of Beaugé and Roig (Beaugé, C., Roig, F.V. [2001]. Icarus, 153, 391-415), and compare the results with the numerical estimations by Brož and Rosehnal (Brož, M., Rosehnal, J. [2011]. Mon. Not. R. Astron. Soc. 414, 565-574). For asteroids that were already numbered in 2011, both methods yield very similar results, while significant differences were found for those bodies that became numbered after 2011.

  20. Astronomy Teaching in Argentina in the 19th Century. (Spanish Title: La Enseñanza de la Astronomía en la Argentina del Siglo XIX.) O Ensino de Astronomia na Argentina no Século XIX

    Science.gov (United States)

    Norberto Cornejo, Jorge; Santilli, Haydée

    2010-12-01

    Sarmiento believed that Copernican astronomy was one of the critical scientific disciplines to the formation of a "modern" citizen. In this work, we shall study astronomical science from two points of view: from the scientific knowledge and the educational presentation of such knowledge. Our study will address in Argentina in 19th century, starting from the initiative of Bernardino Rivadavia in 1821, who founded an astronomic observatory at Buenos Aires, until the first activities of the observatories at Córdoba and La Plata. On both lines, scientific and educative, we shall analyze the influence of positivist ideas. We shall highlight epistemological differences between both observatories, Córdoba's based on French positivism and La Plata's based on German positivism. We shall also show the different attitude of both observatories towards education. We shall see the way in which positivist ideas had great relevance in the training of elementary school teachers. We shall also establish the relevant influence of the socio-historical context over the astronomical development, and show that astronomy was a fundamental social factor at Argentina history. Domingo F. Sarmiento consideraba que la astronomía copernicana era una de las disciplinas científicas fundamentales para la conformación de un ciudadano "moderno". En este trabajo estudiaremos la ciencia astronómica desde dos vertientes: la referida específicamente al conocimiento científico y aquella vinculada con la presentación educativa de dicho conocimiento. Nuestro estudio se desarrollará en Argentina durante el siglo XIX, desde la iniciativa de Bernardino Rivadavia en 1821, de establecer en Buenos Aires un observatorio astronómico, hasta las primeras actividades de los observatorios de Córdoba y de La Plata. En ambas vertientes, científica y educativa, analizaremos la influencia de las ideas positivistas. Resaltaremos las diferencias epistemológicas entre los dos observatorios, orientado el primero

  1. High energy neutrinos from astrophysical accelerators of cosmic ray nuclei

    Science.gov (United States)

    Anchordoqui, Luis A.; Hooper, Dan; Sarkar, Subir; Taylor, Andrew M.

    2008-02-01

    Ongoing experimental efforts to detect cosmic sources of high energy neutrinos are guided by the expectation that astrophysical accelerators of cosmic ray protons would also generate neutrinos through interactions with ambient matter and/or photons. However, there will be a reduction in the predicted neutrino flux if cosmic ray sources accelerate not only protons but also significant numbers of heavier nuclei, as is indicated by recent air shower data. We consider plausible extragalactic sources such as active galactic nuclei, gamma ray bursts and starburst galaxies and demand consistency with the observed cosmic ray composition and energy spectrum at Earth after allowing for propagation through intergalactic radiation fields. This allows us to calculate the expected neutrino fluxes from the sources, normalized to the observed cosmic ray spectrum. We find that the likely signals are still within reach of next generation neutrino telescopes such as IceCube.PACS95.85.Ry98.70.Rz98.54.Cm98.54.EpReferencesFor a review, see:F.HalzenD.HooperRep. Prog. Phys.6520021025A.AchterbergIceCube CollaborationPhys. Rev. Lett.972006221101A.AchterbergIceCube CollaborationAstropart. Phys.262006282arXiv:astro-ph/0611063arXiv:astro-ph/0702265V.NiessANTARES CollaborationAIP Conf. Proc.8672006217I.KravchenkoPhys. Rev. D732006082002S.W.BarwickANITA CollaborationPhys. Rev. Lett.962006171101V.Van ElewyckPierre Auger CollaborationAIP Conf. Proc.8092006187For a survey of possible sources and event rates in km3 detectors see e.g.,W.BednarekG.F.BurgioT.MontaruliNew Astron. Rev.4920051M.D.KistlerJ.F.BeacomPhys. Rev. D742006063007A. Kappes, J. Hinton, C. Stegmann, F.A. Aharonian, arXiv:astro-ph/0607286.A.LevinsonE.WaxmanPhys. Rev. Lett.872001171101C.DistefanoD.GuettaE.WaxmanA.LevinsonAstrophys. J.5752002378F.A.AharonianL.A.AnchordoquiD.KhangulyanT.MontaruliJ. Phys. Conf. Ser.392006408J.Alvarez-MunizF.HalzenAstrophys. J.5762002L33F.VissaniAstropart. Phys.262006310F.W

  2. Evolution of the Astronomy Concepts Along Basic Education Cycle. (Breton Title: Evolução dos Conceitos de Astronomia no Decorrer da Educação Básica.) La Evolución de los Conceptos de Astronomía Durante la Educación Básica

    Science.gov (United States)

    Darroz, Luiz Marcelo; da Rosa, Cleci Werner; Becker da Rosa, Álvaro; Samudio Pèrez, Carlos Ariel

    2014-07-01

    learning of astronomy in basic education. Embora a astronomia seja considerada uma das ciências mais antigas da humanidade e ainda que a compreensão de seus conceitos tenha trazido enormes avanços para a Ciência e, consequentemente, para a sociedade, observa-se que uma parcela significativa de pessoas encontra-se à margem desses conhecimentos. De acordo com os Parâmetros Curriculares Nacionais para a Educação Básica, cabe à escola a difusão dos conceitos cientificamente corretos, entre eles os relacionados à área de astronomia. Pertinente a essa questão, apresenta-se uma pesquisa realizada com 140 estudantes do nono ano do ensino fundamental e com 120 estudantes da terceira série do ensino médio de quatro escolas da região de Passo Fundo/RS. Buscou-se averiguar, por meio de um questionário composto de questões abertas e de múltipla escolha, o conhecimento desse grupo de estudantes acerca de termos e fenômenos astronômicos básicos e, também, verificar se o índice de acertos cresce à medida que eles avançam nas diferentes e gradativas séries dos ensinos fundamental e médio. De modo geral, os resultados apresentados demonstram que o ensino de astronomia na educação básica enfrenta deficiências. Das 20 questões investigadas, em 17 os índices de acertos são semelhantes nas respostas dadas por estudantes de nível fundamental e médio, revelando que muitas concepções equivocadas permanecem ao longo da educação básica. Isso evidencia que tais temas não são - ou são pouco - abordados durante esses dois níveis de escolarização. Assim, conclui-se que a discussão dos conceitos relacionados com a astronomia deve receber maior ênfase na abordagem dos diferentes conteúdos, sendo necessária uma ação nacional em prol do seu ensino. Acredita-se que essa ação nacional deve estar apoiada em um pilar triplo de atores coletivos: comunidade científica, comunidade astronômica semiprofissional e comunidade escolar. Por fim, esse pilar seria

  3. Asteroid phase curve analysis with the H, G 1, G 2 photometric phase function: application to the PTF survey observations

    Science.gov (United States)

    Penttilä, Antti; Cellino, Alberto; Lu, Xiaoping; Shevchenko, Vasilij G.; Muinonen, Karri

    2016-10-01

    .A. Oszkiewicz et al. (2012). Icarus 219, 283–296.[2] V.G. Shevchenko et al. (2016). PSS 123, 101–116.[3] K. Muinonen et al. (2010). Icarus 209, 542–555.[4] A. Penttilä et al. (2016). PSS 123, 117–125.[5] A. Waszczak et al. (2015). Astron J 150(3).

  4. Binary asteroid population. 3. Secondary rotations and elongations

    Science.gov (United States)

    Pravec, P.; Scheirich, P.; Kušnirák, P.; Hornoch, K.; Galád, A.; Naidu, S. P.; Pray, D. P.; Világi, J.; Gajdoš, Š.; Kornoš, L.; Krugly, Yu. N.; Cooney, W. R.; Gross, J.; Terrell, D.; Gaftonyuk, N.; Pollock, J.; Husárik, M.; Chiorny, V.; Stephens, R. D.; Durkee, R.; Reddy, V.; Dyvig, R.; Vraštil, J.; Žižka, J.; Mottola, S.; Hellmich, S.; Oey, J.; Benishek, V.; Kryszczyńska, A.; Higgins, D.; Ries, J.; Marchis, F.; Baek, M.; Macomber, B.; Inasaridze, R.; Kvaratskhelia, O.; Ayvazian, V.; Rumyantsev, V.; Masi, G.; Colas, F.; Lecacheux, J.; Montaigut, R.; Leroy, A.; Brown, P.; Krzeminski, Z.; Molotov, I.; Reichart, D.; Haislip, J.; LaCluyze, A.

    2016-03-01

    We collected data on rotations and elongations of 46 secondaries of binary and triple systems among near-Earth, Mars-crossing and small main belt asteroids. 24 were found or are strongly suspected to be synchronous (in 1:1 spin-orbit resonance), and the other 22, generally on more distant and/or eccentric orbits, were found or are suggested to have asynchronous rotations. For 18 of the synchronous secondaries, we constrained their librational angles, finding that their long axes pointed to within 20° of the primary on most epochs. The observed anti-correlation of secondary synchroneity with orbital eccentricity and the limited librational angles agree with the theories by Ćuk and Nesvorný (Ćuk, M., Nesvorný, D. [2010]. Icarus 207, 732-743) and Naidu and Margot (Naidu, S.P., Margot, J.-L. [2015]. Astron. J. 149, 80). A reason for the asynchronous secondaries being on wider orbits than synchronous ones may be longer tidal circularization time scales at larger semi-major axes. The asynchronous secondaries show relatively fast spins; their rotation periods are typically VH, the secondary rotations are single-periodic with no signs of chaotic rotation and their periods are constant on timescales from weeks to years. The secondary equatorial elongations show an upper limit of a2 /b2 ∼ 1.5 . The lack of synchronous secondaries with greater elongations appears consistent, considering uncertainties of the axis ratio estimates, with the theory by Ćuk and Nesvorný that predicts large regions of chaotic rotation in the phase space for a2 /b2 ≳√{ 2 } . Alternatively, secondaries may not form or stay very elongated in gravitational (tidal) field of the primary. It could be due to the secondary fission mechanism suggested by Jacobson and Scheeres (Jacobson, S.A., Scheeres, D.J. [2011]. Icarus 214, 161-178), as its efficiency is correlated with the secondary elongation. Sharma (Sharma, I. [2014]. Icarus 229, 278-294) found that rubble-pile satellites with a2 /b2 ≲ 1

  5. Diagnosing the Source Region of a Solar Burst on 26 September 2011 by Using Microwave Type-III Pairs

    Science.gov (United States)

    Tan, B. L.; Karlický, M.; Mészárosová, H.; Kashapova, L.; Huang, J.; Yan, Y.; Kontar, E. P.

    2016-10-01

    We report a peculiar and interesting train of microwave Type-III pair bursts in the impulsive rising phase of a solar flare on 26 September 2011. The observations include radio spectrometers at frequencies of 0.80 - 2.00 GHz from the Ondřejov radiospectrograph in the Czech Republic (ORSC), hard X-ray from the Ramaty High-Energy Solar Spectroscopic Imager (RHESSI) and Gamma-Ray Burst Monitor onboard the Fermi Space Telescope ( Fermi/GRB), EUV images from the Sun Watcher using APS detectors and image Processing instrument onboard the Project for Onboard Autonomy 2 (SWAP/PROBA2), and magnetograms from the Helioseismic and Magnetic Imager onboard the Solar Dynamic Observatory (SDO/HMI). By using a recently developed method (Tan et al., Res. Astron. Astrophys. 16, 82, 2016a), we diagnosed the plasma density, temperature, plasma-β, magnetic field near the source region, the energy of energetic electrons, and the distance between the acceleration region and the emission start sites of Type-III bursts. From the diagnostics, we find that i) The plasma density, temperature, magnetic field, and the distance between the acceleration region and the emission start sites have almost no obvious variations during the period of Type-III pair trains, while the energy of electrons has an obvious peak value that is consistent with the hard X-ray emission. ii) The plasma-β is much higher than unity, showing a highly dynamic process near the emission start site of Type-III bursts. iii) Although the reversed-slope Type-III branches drift more slowly by one order of magnitude than that of the normal Type-IIIs, the related descending and ascending electrons still could have energy of the same order of magnitude. These facts indicate that both the ascending and descending electrons are possibly accelerated by a similar mechanism and in a small source region. These diagnostics can help us to understand the physics in the source region of solar bursts.

  6. Ionized gas diagnostics from protoplanetary discs in the Orion nebula and the abundance discrepancy problem

    Science.gov (United States)

    Mesa-Delgado, A.; Núñez-Díaz, M.; Esteban, C.; García-Rojas, J.; Flores-Fajardo, N.; López-Martín, L.; Tsamis, Y. G.; Henney, W. J.

    2012-10-01

    for the intrinsic spectra of 177-341, while the background emission presents the typical ADF(O2 +) observed in the Orion nebula (0.16 ± 0.11 dex). We conclude that the presence of high-density ionized gas is severely affecting the abundances determined from CELs and, therefore, those from RLs should be considered as a better approximation to the true abundances. Based on observations collected at the Centro Astronómico Hispano Alemán (CAHA) at Calar Alto, operated jointly by the Max-Planck Institut für Astronomie and the Instituto de Astrofísica de Andalucía (CSIC).

  7. A new method to find the potential center of N-Body systems

    Directory of Open Access Journals (Sweden)

    F. Cruz

    2002-01-01

    Full Text Available Se presenta un método rápido para encontrar el centro del potencial de una distribución de N-cuerpos. El método usa un algoritmo iterativo que aprovecha el hecho de que el gradiente del potencial es nulo en su centro; emplea asimismo un radio de suavizado para evitar quedar atrapado en mínimos locales. Se ha probado el método con modelos de King (cuyos núcleos, de densidad relativamente constante, hacen particularmente difícil la determinación numérica de este centro, y se ha comparado su eficiencia y precisión con un método más directo, aunque de cálculo intensivo, basado en mallas cartesianas de resolución espacial creciente. En todos los casos, ambos métodos convergen al mismo centro dentro de la resolución de la malla, aunque el método iterativo es dos _ordenes de magnitud más rápido. Utilizamos este método en un problema astronómico: la evolución de un modelo de King de 105 partículas, en orbita alrededor de un potencial fijo representativo de nuestra Galaxia. Se utilizó un código de N-cuerpos con expansión en armónicos esféricos, en el que la determinación del centro del potencial es esencial para un cálculo correcto de las fuerzas. Se comparó esta simulación con el mismo código pero con un método empleado anteriormente para determinar el centro de expansión (White 1983. Con nuestra rutina se obtienen mejores resultados en la conservación de energía y de la masa.

  8. Variaciones seculares de período en las RR Lyrae de ω~Centauri

    Science.gov (United States)

    Marraco, H. G.; Milesi, G. E.

    Utilizando 689 observaciones de 35 estrellas RR Lyrae del cúmulo globular ω Centauri hemos obtenido nuevas determinaciones de sus períodos y sus correspondientes variaciones seculares. Las observaciones fueron obtenidas de la literatura con la excepción de un grupo 66 determinaciones que se presentan por vez primera aquí. Utilizando el parámetro testigo σ descripto en Marraco & Muzzio (Publ. Astron. Soc. Pacific 92, 700, 1980), hemos realizado un ajuste bidimensional en P y β (donde β es la variación secular del período). Con este fin la totalidad de las 689 observaciones fueron llevadas a un sistema fotométrico común. Para esto se realizó un cuidadoso análisis de los numerosos errores en la identificación de las estrellas de las series de comparación. Los resultados de los ajustes bidimensionales fueron analizados utilizando técnicas de procesamiento de imágenes. Con este fin el parámetro de ajuste σ fue representado como función de P y β. En las imágenes resultantes se buscaron los mínimos y al menor de ellos se lo aceptó como período instantáneo verdadero y su variación secular β. La determinación precisa de cada parámetro se realizó mediante ajuste de gaussianas y se determinaron sus errores. A modo de ejemplo la variable #8 fue analizada en una matriz de 501 × 501 elementos representando el parámetro σ para valores comprendidos entre 0,521034 valores el parámetro testigo resulta σ= 0,127 . Si no se tiene en cuenta la variación secular del período y se busca aquél de mejor ajuste para β = 0, se obtiene P = 0,5212960 días, pero entonces el parámetro de ajuste resulta tan alto como σ = 0,23 .

  9. Follow-up spectroscopic observations of HD 107148 B: A new white dwarf companion of an exoplanet host star

    Science.gov (United States)

    Mugrauer, M.; Dinçel, B.

    2016-07-01

    We report on our follow-up spectroscopy of HD 1071478 B, a recently detected faint co-moving companion of the exoplanet host star HD 107148 A. The companion is separated from its primary star by about 35 arcsec (or 1790 AU of projected separation) and its optical and near infrared photometry is consistent with a white dwarf, located at the distance of HD 107148 A. In order to confirm the white dwarf nature of the co-moving companion, we obtained follow-up spectroscopic observations of HD 107148 B with CAFOS at the CAHA 2.2 m telescope. According to our CAFOS spectroscopy HD 107148 B is a DA white dwarf with an effective temperature in the range between 5900 and 6400 K. The properties of HD 107148 B can further be constrained with the derived effective temperature and the known visual and infrared photometry of the companion, using evolutionary models of DA white dwarfs. We obtain for HD 107148 B a mass of 0.56±0.05 M_ȯ, a luminosity of (2.0±0.2)×10-4 L_ȯ, log g [cm s-2])=7.95±0.09, and a cooling age of 2100±270 Myr. With its white dwarf companion the exoplanet host star HD 107148 A forms an evolved stellar system, which hosts at least one exoplanet. So far, only few of these evolved systems are known, which represent only about 5 % of all known exoplanet host multiple stellar systems. HD 107148 B is the second confirmed white dwarf companion of an exoplanet host star with a projected separation to its primary star of more than 1000 AU. Based on observations collected at the Centro Astronómico Hispano Alemán (CAHA) at Calar Alto, operated jointly by the Max-Planck Institut für Astronomie and the Instituto de Astrofísica de Andalucía (CSIC).

  10. Identification of Postclassic Maya Constellations from the Venus Pages of the Dresden Codex

    Directory of Open Access Journals (Sweden)

    Changbom Park

    2010-01-01

    Full Text Available Ancient Mayan civilization, flourished from 1200 B.C. to 1500 A.D., has left numerous hieroglyphic texts on astronomical observations and calendar. In particular, the Dresden Codex contains the most details of such ancient Mayan heritage. Page 24 and those from 46 to 50 of the Dresden Codex describe the Mayan Venus calendar along with the augural descriptions. We note that the calendar in Dresden Codex is Venus-solar calendar. Our work focuses on the possibility that the calendar was made to work in conjunction with the periodic appearance of constellations on the sky. By analyzing the descriptions in the Venus pages, we propose that the columns in each page describe the motion of Venus with respect to major constellations at dates corresponding to special events while the calendar dates increase horizontally in the synodic period of Venus. We present twenty Mayan constellations identified from the Venus pages assuming that the first date of page 46 is February 6, 1228. We also report our understanding of verb expressions about the relative movement of constellations and Venus.La civilización maya, que floreció del 1200 a.C. a 1500 d.C., dejó numerosos textos jeroglíficos sobre el calendario y observaciones astronómicos. El Códice de Dresde, en particular, contiene el más detallado de dichos antiguos legados mayas. Las páginas 24 y 46 a 50 de dicho códice describen el calendario de Venus con los augurios correspondientes. Nosotros hemos notado que éste es un calendario Venus-Solar, y nuestro trabajo se enfoca sobre la posibilidad de que estuviera hecho para trabajar en conjunción con la aparición de determinadas constelaciones en el cielo. Es a través del análisis y descripción de las páginas de Venus que proponemos que las columnas en cada página describen el movimiento de Venus respecto de constelaciones mayores, en fechas que corresponden a eventos especiales, mientras que las fechas calendáricas se incrementan

  11. Hα3: an Hα imaging survey of HI selected galaxies from ALFALFA. VI. The role of bars in quenching star formation from z = 3 to the present epoch

    Science.gov (United States)

    Gavazzi, G.; Consolandi, G.; Dotti, M.; Fanali, R.; Fossati, M.; Fumagalli, M.; Viscardi, E.; Savorgnan, G.; Boselli, A.; Gutiérrez, L.; Hernández Toledo, H.; Giovanelli, R.; Haynes, M. P.

    2015-08-01

    redshift evolution for Mknee. Our study highlights how the formation of strong bars in massive galaxies is an important mechanism in regulating the redshift evolution of the sSFR for field main-sequence galaxies. Based on observations taken at the observatory of San Pedro Martir (Baja California, Mexico), belonging to the Mexican Observatorio Astronómico Nacional.

  12. A Continuing Analysis of Possible Activity Drivers for the Enigmatic Comet 29P/Schwassmann-Wachmann 1

    Science.gov (United States)

    Schambeau, Charles; Fernández, Yanga; Samarasinha, Nalin H.; Mueller, Beatrice E. A.; Sarid, Gal; Meech, Karen Jean; Woodney, Laura

    2016-01-01

    We present results from our effort to understand activity drivers in Comet 29P/Schwassmann-Wachmann 1 (SW1). In a nearly circular orbit around 6 AU, outside of the water-sublimation zone, SW1 is continuously active and experiences frequent outbursts. Our group's effort is focusing on finding constraints on physical and dynamical properties of SW1's nucleus and their incorporation into a thermophysical model [1,2] to explain this behavior. We are currently analyzing coma morphology of SW1 before, during, and after outburst placing constraints on the spin-pole direction, spin period, and surface areas of activity. In addition, we are using the thermal model to investigate if the continuous activity comes from one or multiple processes, such as the release of trapped supervolatiles during the amorphous to crystalline (A-C) water ice phase transition and/or the direct sublimation of pockets of supervolatile ices. The supervolatile ices may be primordial or from the condensation of gases released during the A-C phase transition. To explain the possibly quasi-periodic but frequent outbursts, we are looking into subsurface cavities where internal pressures can build, reaching and exceeding surrounding material strengths [3,4] and/or thermal waves reaching a pocket of supervolatile ices, causing a rapid increase in the sublimation rate. For all these phenomena, the model is constrained by comparing the output dust mass loss rate and its variability with what has been observed through optical imaging of the comet at various points in its orbit. We will present preliminary thermal modeling of a homogeneous progenitor nucleus that evolves into a body showing internal material layering, the generation of CO and CO2 ice pockets, and the production of outbursts, thus bringing us closer to explaining the behavior of this intriguing comet. [1] Sarid, G., et al.: 2005, PASP, 117, 843. [2] Sarid, G.: 2009, PhD Thesis, Tel Aviv Univ. [3] Gronkowski, P., 2014, Astron. Nachr./AN 2, No

  13. Astronomia cultural e meio ambiente segundo uma abordagem holística

    Science.gov (United States)

    Jafelice, L. C.

    2003-08-01

    Neste trabalho ampliamos a discussão da abordagem holística para o ensino de astronomia que temos desenvolvido nos últimos anos, analisamos novos resultados e apresentamos exemplos práticos para interessados em experimentá-la. A constatação básica a orientar este enfoque é que cursos introdutórios em astronomia costumam ser excessiva e prematuramente técnicos, além de assumirem uma visão tradicional, muito estreita, do que seja educação científica, herdada da era cartesiana e positivista da ciência. Fundamentamos porque é importante que elementos de astronomia cultural ofereçam o mote e constituam o eixo norteador daqueles cursos e porque é urgente revermos a visão que temos da relação entre astronomia e meio ambiente. Um ponto central nesta abordagem é explorar formas de reativar e atualizar uma relação orgânica com o meio e excitar a consciência de nossa inevitável e profunda interdependência com ele em nível cósmico. Neste trabalho exemplificamos a possibilidade de concretização desta proposta em três diferentes situações: disciplinas de cursos de licenciatura em geografia e em física; escolas de nível fundamental; e, neste caso ainda a ser implementada, comunidades carentes. Estes casos envolvem públicos e espaços diferenciados para educação formal e não-formal. Dos casos já implementados, destacamos os resultados alcançados pelos alunos: enriquecimento cultural, aprendizagem significativa de conteúdos astronômicos tradicionais; mudanças de comportamento, incorporando contato diário com o céu; e freqüentes vivências de sentimentos empáticos que redirecionam a relação com a natureza e a consciência ecológica global. Além disto, para interessados em aplicar esta proposta, também socializamos procedimentos e cuidados para a implementação de ações alternativas consonantes com a mesma. (PPGECNM/UFRN; PRONEX/FINEP; NUPA/USP; Temáticos/FAPESP)

  14. Usina de ciências: um espaço pedagógico para aprendizagens múltiplas

    Science.gov (United States)

    Martin, V. A. F.; Poppe, P. C. R.; Orrico, A. C. P.; Pereira, M. G.

    2003-08-01

    Entendemos que o Ensino de Astronomia é especialmente apropriado para motivar os alunos e aprofundar conteúdos em diversas áreas do conhecimento, pois envolve temas ligados à Física, Matemática, Química, Computação, Tratamento de Imagens e Instrumentação de Alta Precisão, além daqueles pertinentes as áreas de Geografia, História e Antropologia. Contudo, apesar do caráter interdisciplinar que esta ciência possui, a realidade atual é que a maioria dos professores em sala de aula não foram devidamente capacitados, durante o período de formação acadêmica, para ministrar conteúdos de Astronomia nos atuais Ensinos Fundamental e Médio. Neste trabalho, discutiremos de maneira ampla, num primeiro momento, a realidade do atual ensino de ciências praticado no Estado da Bahia, apontando por dependência administrativa, o crescimento e a redução do número de escolas, da taxa de analfabetismo por faixa etária, da escolarização, do atendimento, da aprovação, reprovação e abandono, de equipamentos e laboratórios e o grau de formação dos nossos atuais professores em pleno exercício de atividade docente. Num segundo momento, discutiremos o papel do Observatório Astronômico Antares/UEFS dentro desse contexto, ou seja, suas ações implementadas ao longo dos últimos anos e em particular, o recente projeto de extensão Ensino e Difusão de Astronomia, financiado pela Fundação Vitae, que procura traduzir no lúdico, no brincar de ciências, um espaço pedagógico para aprendizagens múltiplas. Neste, o papel do professor multiplicador associado ao laboratório de kits didáticos, de fácil construção e manipulação (alguns dos quais serão mostrados), perfazem os principais veículos para o desenvolvimento de conhecimentos, atitudes, habilidades e valores que preparam os nossos alunos para a carreira técnico-científica e para sua participação crítica e criativa na Sociedade.

  15. The chemically peculiar double-lined spectroscopic binary HD 90264

    Science.gov (United States)

    Quiroga, C.; Torres, A. F.; Cidale, L. S.

    2010-10-01

    Context. HD 90264 is a chemically peculiar (CP) double-lined spectroscopic binary system of the type He-weak. Double-lined binaries are unique sources of data for stellar masses, physical properties, and evolutionary aspects of stars. Therefore, the determination of orbital elements is of great importance to study how the physical characteristics of CP stars are affected by a companion. Aims: We carried out a detailed spectral and polarimetric study of the spectroscopic binary system HD 90264 to characterize its orbit, determine the stellar masses, and investigate the spectral variability and possible polarization of the binary components. Methods: We employed medium-resolution échelle spectra and polarimetric data obtained at the 2.15-m telescope at CASLEO Observatory, Argentina. We measured radial velocities and line equivalent widths with IRAF packages. The radial velocity curves of both binary components were obtained combining radial velocity data derived from the single line of Hg II λ3984 Åand the double lines of Mg II λ4481 Å. Polarimetric data were studied by means of the statistical method of Clarke & Stewart and the Welch test. Results: We found that both components of the binary system are chemically peculiar stars, deficient in helium, where the primary is a He variable and the secondary is a Hg-Mn star. We derived for the first time the orbital parameters of the binary system. We found that the system has a quasi-circular orbit (e ~ 0.04) with an orbital period of 15.727 days. Taking into account the circular orbit solution, we derived a mass ratio of q = MHe-w/MHg-Mn = 1.22. We also found a rotational period of around 15-16 days, suggesting a spin-orbit synchronization. Possible signs of intrinsic polarization have also been detected. Conclusions: HD 90264 is the first known binary system comprised of a He variable star as the primary component and a Hg-Mn star as the secondary one. Based on observations taken at Complejo Astronómico El

  16. Macroclumping as solution of the discrepancy between Hα and P v mass loss diagnostics for O-type stars

    Science.gov (United States)

    Šurlan, B.; Hamann, W.-R.; Aret, A.; Kubát, J.; Oskinova, L. M.; Torres, A. F.

    2013-11-01

    observations collected with the Perek 2-m Telescope of the Ondřejov Observatory, Czech Republic.Based on observations taken at the Complejo Astronómico El Leoncito (CASLEO), operated under an agreement between the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina, the Secretaría de Ciencia y Tecnología de la Nación, and the National Universities of La Plata, Córdoba, and San Juan.Appendix A is available in electronic form at http://www.aanda.org

  17. Observational constraints for the circumstellar disk of the B[e] star CPD-52 9243

    Science.gov (United States)

    Cidale, L. S.; Borges Fernandes, M.; Andruchow, I.; Arias, M. L.; Kraus, M.; Chesneau, O.; Kanaan, S.; Curé, M.; de Wit, W. J.; Muratore, M. F.

    2012-12-01

    interferometric data are necessary to determine a possible binary nature of the star. Based on observations taken with: 1) Telescopes at Paranal ESO Observatory under the program 085.D-0454 and 385.D-0513A; 2) Gemini South/Phoenix instrument, science program GS-2010A-Q-41; 3) J. Sahade Telescope at Complejo Astronómico El Leoncito (CASLEO), operated under an agreement between the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina, the Secretaría de Ciencia y Tecnología de la Nación and the National Universities of La Plata, Córdoba and San Juan.

  18. Two new pulsating low-mass pre-white dwarfs or SX Phoenicis stars?

    Science.gov (United States)

    Corti, M. A.; Kanaan, A.; Córsico, A. H.; Kepler, S. O.; Althaus, L. G.; Koester, D.; Sánchez Arias, J. P.

    2016-03-01

    Context. The discovery of pulsations in low-mass stars opens an opportunity to probe their interiors and determine their evolution by employing the tools of asteroseismology. Aims: We aim to analyse high-speed photometry of SDSS J145847.02+070754.46 and SDSS J173001.94+070600.25 and discover brightness variabilities. In order to locate these stars in the Teff - log g diagram, we fit optical spectra (SDSS) with synthetic non-magnetic spectra derived from model atmospheres. Methods: To carry out this study, we used the photometric data we obtained for these stars with the 2.15 m telescope at CASLEO, Argentina. We analysed their light curves and applied the discrete Fourier transform (FT) to determine the pulsation frequencies. Finally, we compare both stars in the Teff - log g diagram, with two known pre-white dwarfs and seven pulsating pre-ELM white dwarf stars, δ Scuti, and SX Phe stars Results: We report the discovery of pulsations in SDSS J145847.02+070754.46 and SDSS J173001.94+070600.25. We determine their effective temperature and surface gravity to be Teff = 7972 ± 200 K, log g = 4.25 ± 0.5 and Teff = 7925 ± 200 K, log g = 4.25 ± 0.5, respectively. With these parameters, these new pulsating low-mass stars can be identified with either ELM white dwarfs (with ~0.17 M⊙) or more massive SX Phe stars. We identified pulsation periods of 3278.7 and 1633.9 s for SDSS J145847.02+070754.46 and a pulsation period of 3367.1 s for SDSS J173001.94+070600.25. These two new objects, together with those of Maxted et al. (2013, 2014), indicate the possible existence of a new instability domain towards the late stages of evolution of low-mass white dwarf stars, although their identification with SX Phe stars cannot be discarded. Visiting Astronomer, Complejo Astronómico El Leoncito operated under agreement between the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina and the National Universities of La Plata, Córdoba, and San Juan.

  19. Interplanetary dust physical properties deduced from scattered and emitted light simulations

    Science.gov (United States)

    Lasue, J.; Levasseur-Regourd, A. C.; Fray, N.; Cottin, H.

    2007-08-01

    presence of an extended zone of thermal degradation [4]. The drastic change of P(?=90°) closer to the Sun, below 0.5 AU, could be the result of other minerals (e.g. silicates) degradations in this zone. [1] Levasseur-Regourd et al., In: Interplanetary dust, Grün, Gustafson, Dermott, Fechtig (eds), pp. 57 (2001) [2] Lasue and Levasseur-Regourd, J. Quant. Spectros. Radiat. Transfer 100, 220 (2006) [3] Fray et al., Meteoritics and Planetary Science 39, 581, (2004) [4] Lasue et al., Astron. Astrophys. (submitted)

  20. VISIR upgrade overview and status

    Science.gov (United States)

    Kerber, Florian; Käufl, Hans-Ulrich; Baksai, Pedro; Di Lieto, Nicola; Dobrzycka, Danuta; Duhoux, Philippe; Finger, Gert; Heikamp, Stephanie; Ives, Derek; Jakob, Gerd; Lundin, Lars; Mawet, Dimitri; Mehrgan, Leander; Momany, Yazan; Moreau, Vincent; Pantin, Eric; Riquelme, Miguel; Sandrock, Stefan; Siebenmorgen, Ralf; Smette, Alain; Taylor, Julian; van den Ancker, Mario; Valdes, Guillermo; Venema, Lars; Weilenmann, Ueli

    2014-07-01

    We present an overview of the VISIR upgrade project. VISIR is the mid-infrared imager and spectrograph at ESO's VLT. The project team is comprised of ESO staff and members of the original VISIR consortium: CEA Saclay and ASTRON. The project plan is based on input from the ESO user community with the goal of enhancing the scientific performance and efficiency of VISIR by a combination of measures: installation of improved hardware, optimization of instrument operations and software support. The cornerstone of the upgrade is the 1k by 1k Si:As AQUARIUS detector array (Raytheon) which has been carefully characterized in ESO's IR detector test facility (modified TIMMI 2 instrument). A prism spectroscopic mode will cover the N-band in a single observation. New scientific capabilities for high resolution and high-contrast imaging will be offered by sub-aperture mask (SAM) and phase-mask coronagraphic (4QPM/AGPM) modes. In order to make optimal use of favourable atmospheric conditions a water vapour monitor has been deployed on Paranal, allowing for real-time decisions and the introduction of a user-defined constraint on water vapour. During the commissioning in 2012 it was found that the on-sky sensitivity of the AQUARIUS detector was significantly below expectations and that VISIR was not ready to go back to science operations. Extensive testing of the detector arrays in the laboratory and on-sky enabled us to diagnose the cause for the shortcoming of the detector as excess low frequency noise (ELFN). It is inherent to the design chosen for this detector and can't be remedied by changing the detector set-up. Since this is a form of correlated noise its impact can be limited by modulating the scene recorded by the detector. We have studied several mitigation options and found that faster chopping using the secondary mirror (M2) of the VLT offers the most promising way forward. Faster M2 chopping has been tested and is scheduled for implementation before the end of 2014

  1. Shedding light on a dark state: The energetically lowest quintet state of C2

    Science.gov (United States)

    Bornhauser, P.; Sych, Y.; Knopp, G.; Gerber, T.; Radi, P. P.

    2011-01-01

    In this work we present a deperturbation study of the d ^3Π _g, v=6 state of C2 by double-resonant four-wave mixing spectroscopy. Accurate line positions of perturbed transitions are unambiguously assigned by intermediate level labeling. In addition, extra lines are accessible by taking advantage of the sensitivity and high dynamic range of the technique. These weak spectral features originate from nearby-lying dark states that gain transition strength through the perturbation process. The deperturbation analysis of the complex spectral region in the (6,5) and (6,4) bands of the Swan system (d^3Π _g-a ^3Π _u) unveils the presence of the energetically lowest high-spin state of C2 in the vicinity of the d ^3Π _g, v=6 state. The term energy curves of the three spin components of the d state cross the five terms of the 1^5Π _g state at rotational quantum numbers N ⩽ 11. The spectral complexity for transitions to the v = 6 level of d ^3Π _g state is further enhanced by an additional perturbation at N = 19 and 21 owing to the b ^3Σ _g^-, v=19 state. The spectroscopic characterization of both dark states is accessible by the measurement of 122 "window" levels. A global fit of the positions to a conventional Hamiltonian for a linear diatomic molecule yields accurate molecular constants for the quintet and triplet perturber states for the first time. In addition, parameters for the spin-orbit and L-uncoupling interaction between the electronic levels are determined. The detailed deperturbation study unravels major issues of the so-called high-pressure bands of C2. The anomalous nonthermal emission initially observed by Fowler in 1910 [Mon. Not. R. Astron. Soc. 70, 484 (1910)] and later observed in numerous experimental environments are rationalized by taking into account "gateway" states, i.e., rotational levels of the d ^3Π _g, v=6 state that exhibit significant ^5Π _g character through which all population flows from one electronic state to the other.

  2. A Tri-band Cryogenic Receiver for the RAEGE Project Antennas

    Science.gov (United States)

    López-Pérez, J. A.; Tercero, F.; Serna, J. M.; López-Fernández, J. A.

    2012-12-01

    The Spanish Centro de Desarrollos Tecnológicos (CDT) is developing a tri-band cryogenic receiver for the first light observations of the first RAEGE project antenna in Centro Astronómico de Yebes observatory in the framework of the VLBI2010 project. The RAEGE project plans to install three new ring-focus 13.2 meter antennas in compliance with the VLBI2010 specifications. These antennas are under construction. The first light receiver envisaged for these antennas will operate in the S (2.2 — 2.7 GHz), X (7.5 — 9 GHz), and Ka (28 — 33 GHz) bands, simultaneously, in order to be backward compatible with non-VLBI2010 stations and forward compatible with new ones. The receiver feed designed to illuminate the ring-focus antenna is made of a coaxial waveguide, for the S and X bands, and a circular waveguide for the Ka band. Four outputs from their corresponding field probes at S and X bands must be combined with 180 ° and 90 ° hybrid circuits to get simultaneous dual-circular polarization. In the Ka band case, the two circular polarizations are split by means of a classical septum polarizer. The feed, hybrids, and polarizer will operate at cryogenic temperature in order to minimize their contribution to system noise. The estimated equivalent noise temperature for this receiver is lower than 15 Kelvin for S-band, 20 Kelvin for X-band, and 25 Kelvin for Ka-band. The output signals from the cryostat will be sent to their corresponding room temperature downconverters for later amplification, filtering, and mixing. The final IF signal will range from 500 to 1000 MHz, as in a classical geodetic VLBI receiver, to be backward compatible with non-VLBI2010 stations. An advantage of having the Ka band receiver is that it will allow the radiometric characterization (pointing, tracking, and efficiency) of these antennas during commissioning. In addition, simultaneous X/Ka operation would be possible. The first receiver of this type is planned to be finished by September, 2012

  3. Identification of New Hot Bands in the Blue and Green Band Systems of FeH.

    Science.gov (United States)

    Wilson; Brown

    1999-10-01

    A particularly rich region of the electronic spectrum of FeH from 525 to 545 nm was investigated using the techniques of dispersed and undispersed laser-induced fluorescence. Analysis has led to the discovery that several different electronic transitions are embedded in this region; the (0, 0) and (1, 1) bands of the e(6)Pi-a(6)Delta (green) system, the (0, 2) band of the g(6)Phi-X(4)Delta (intercombination) system, the (0, 1) band of the g(6)Phi-a(6)Delta (blue) system, and the (0, 0) band of the g(6)Phi-b(6)Pi system. Seventy-five lines were assigned in the (0, 1) band of the g(6)Phi-a(6)Delta transition. These, with the assignment of an additional 14 lines in the 583 nm region to the (0, 1) band of the e(6)Pi-a(6)Delta transition, led to the extension of the known term values to higher J values for the Omega = 9/2, 7/2, and 5/2 spin components of the v = 1 level of the a(6)Delta state and the novel characterization of the a(6)Delta(3/2) (v = 1) and g(6)Phi(5/2) (v = 0) components. A further 73 lines were assigned to the first four subbands of the (1, 1) band of the e(6)Pi-a(6)Delta transition and term values for the lowest four spin components of the v = 1 level of the e(6)Pi state were determined. This provides the first experimental measurement of a vibrational interval in one of the higher lying electronic states of FeH. The interval does not appear to vary strongly between the spin components (DeltaG(1/2) = 1717, 1713, 1710 cm(-1) for Omega = 7/2, 5/2, 3/2, respectively). Remarkably few of the hot-band transitions assigned in this work could be identified in the complex, high-temperature spectrum of FeH recorded by P. McCormack and S. O'Connor [Astron. Astrophys. Suppl. 26, 373-380 (1976)]. Copyright 1999 Academic Press. PMID:10479583

  4. Quantum Chemical Evaluation of the Astrochemical Significance of Reactions between S Atom and Acetylene or Ethylene

    Science.gov (United States)

    Woon, David E.

    2007-01-01

    Addition-elimination reactions of S atom in its P-3 ground state with acetylene (C2H2) and ethylene (C2H4) were characterized with both molecular orbital and density functional theory calculations employing correlation consistent basis sets in order to assess the likelihood either reaction might play a general role in astrochemistry or a specific role in the formation of S2 (X (sup 3 SIGMA (sub g) (sup -)) via a mechanism proposed by Saxena and Misra (Mon. Not. R. Astron. Soc. 1995, 272, 89). The acetylene and ethylene reactions proceed through C2H2S ((sup 3)A")) and C2H4S ((sup 3)A")) intermediates, respectively, to yield HCCS ((sup 2)II)) and C2H3S ((sup 2)A')). Substantial barriers were found in the exit channels for every combination of method and basis set considered in this work, which effectively precludes hydrogen elimination pathways for both S + C2H2 and S + C2H4 in the ultracold interstellar medium where only very modest barriers can be surmounted and processes without barriers tend to predominate. However, if one or both intermediates is formed and stabilized efficiently under cometary or dense interstellar cloud conditions, they could serve as temporary reservoirs for S atom and participate in reactions such as S + C2H2S (right arrow) S2 = C2H2 or S + C2H4S (right arrow) S2 + C2H4. For formation and stabilization to be efficient, the reaction must possess a barrier height small enough to be surmountable at low temperatures yet large enough to prevent redissociation to reactants. Barrier heights computed with B3LYP and large basis sets are very low, but more rigorous QCISD(T) and RCCSD(T) results indicate that the barrier heights are closer to 3-4 kcal/mol. The calculations therefore indicate that S + C2H2 or S + C2H4 could contribute to the formation of S2 in comets and may serve as a means to gauge coma temperature. The energetics of the ethylene reaction are more favorable.

  5. Photochemistry in Saturn's Ring-Shadowed Atmosphere: Modeling of Key Molecules and Observations of Dust Content

    Science.gov (United States)

    Edgington, S. G.; Atreya, S. K.; Wilson, E. H.; West, R. A.; Fletcher, L. N.; Baines, K. H.; Bjoraker, G. L.; Momary, T.

    2014-12-01

    -generated molecules and haze. [1] Edgington, S.G., et al., 2012. Photochemistry in Saturn's Ring Shadowed Atmosphere: Modeling, Observations, and Preliminary Analysis. Bull. American. Astron. Soc., 38, 499 (#11.23).

  6. Photochemistry in Saturn’s Ring-Shadowed Atmosphere: Modeling of Key Molecules and Observations of Dust Content

    Science.gov (United States)

    Edgington, Scott G.; Atreya, Sushil K.; Wilson, Eric H.; West, Robert A.; Baines, Kevin H.; Bjoraker, Gordon L.; Fletcher, Leigh N.; Momary, Tom

    2014-11-01

    -generated molecules and haze. [1] Edgington, S.G., et al., 2012. Photochemistry in Saturn’s Ring Shadowed Atmosphere: Modeling, Observations, and Preliminary Analysis. Bull. American. Astron. Soc., 38, 499 (#11.23).

  7. Photochemistry in Saturn’s Ring-Shadowed Atmosphere: Venetian Blinds, Atmospheric Molecules and Observations

    Science.gov (United States)

    Edgington, Scott G.; Atreya, S. K.; Wilson, E. H.; Baines, K. H.; West, R. A.; Bjoraker, G. L.; Fletcher, L. N.; Momary, T.

    2013-10-01

    dynamical mixing. [1] Edgington, S.G., et al., 2012. Photochemistry in Saturn’s Ring Shadowed Atmosphere: Modeling, Observations, and Preliminary Analysis. Bull. American. Astron. Soc., 38, 499 (#11.23).

  8. Photochemistry in Saturn's Ring-Shadowed Atmosphere: Modulation of Key Molecules and Observations of Dust Content

    Science.gov (United States)

    Edgington, Scott G.; Atreya, Sushil H.; Wilson, Eric H.; Baines, Kevin H.; West, Robert A.; Bjoraker, Gordon L.; Fletcher, Leigh N.; Momary, Tom

    2015-04-01

    -generated molecules and haze. [1] Edgington, S.G., et al., 2012. Photochemistry in Saturn's Ring Shadowed Atmosphere: Modeling, Observations, and Preliminary Analysis. Bull. American. Astron. Soc., 38, 499 (#11.23).

  9. Photochemistry in Saturn's Ring-Shadowed Atmosphere: Of Venetian Blinds, Atmospheric Molecules and Observations

    Science.gov (United States)

    Edgington, S. G.; Atreya, S. K.; Wilson, E. H.; Baines, K. H.; West, R. A.; Bjoraker, G. L.; Fletcher, L. N.; Momary, T.

    2013-12-01

    dynamical mixing. [1] Edgington, S.G., et al., 2012. Photochemistry in Saturn's Ring Shadowed Atmosphere: Modeling, Observations, and Preliminary Analysis. Bull. American. Astron. Soc., 38, 499 (#11.23).

  10. Exomol: Molecular Line Lists for Exoplanet and Other Atmospheres

    Science.gov (United States)

    Tennyson, J.; Barber, R. J.; Azzam, A.; Down, M.; Hill, C.; Yurchenko, S. N.

    2011-06-01

    such as ammonia, acetylene, hydrogen peroxide and formaldehyde, are at the very limit of what is computationally possible at present. These will be computed either by direct calculation of the full line list, such as our hot ammonia line list BYTe developed recently [S. N. Yurchenko, R. J. Barber , and J. Tennyson, Mon. Not. R. Astron. Soc., in press, (2011)], or by use of high accuracy vibrational calculations onto which the rotational structure will be grafted using ideas developed from the standard perturbation theory approach to molecular spectroscopy. Tests for acetylene suggest that this latter approach, although intrinsically less accurate, is still able to give reliable results [A. Urru, I. N. Kozin, G. Mulas, B. J. Braams, and J. Tennyson, Mol. Phys., 108, 1973 (2010)]. Data from this project can be accessed at www.exomol.com.

  11. Petrografía y geoquímica de las anfibolitas del cerro La Cocha, Sierra Chica, Córdoba Petrography and geochemistry of the anphibolites from La Cocha Hill, Sierra Chica, Córdoba, Argentina

    Directory of Open Access Journals (Sweden)

    Patricia A Anzil

    2012-06-01

    Full Text Available En la Sierra Chica de Córdoba, a dos kilómetros al sur del Observatorio Astronómico de Bosque Alegre, se encuentran dos variedades litológicas de anfibolitas asociadas al cuerpo ultramáfico de La Cocha. Estas variedades incluyen anfibolitas sin piroxeno, compuestas por hornblenda, plagioclasa, titanita y minerales opacos, emplazadas en el núcleo de la estructura plegada del cuerpo ultramáfico. El segundo grupo son anfibolitas con dos piroxenos, compuestas por hornblenda, plagioclasa, ortopiroxeno (En, clinopiroxeno (Di y como accesorios minerales opacos, apatita, escasa titanita y circón. Estas anfibolitas se encuentran en el encajonante del cuerpo ultramáfico de La Cocha, asociadas a gneises granatíferos sillimaníticos. Con el objetivo de determinar el protolito, que por metamorfismo dieron origen a las anfibolitas, se realizó un estudio geoquímico de roca total. Las anfibolitas con dos piroxenos se clasifican dentro de la serie toleítica y, en base al diagrama de tierras raras se las podría asociar a un ambiente tectónico de generación de tipo N-MORB. Las anfibolitas sin piroxeno, también corresponderían a un ambiente asimilable a N-MORB, con mayor depresión en las tierras raras livianas, sugiriendo probablemente un ambiente de generación del fundido en un manto empobrecido.In the Sierra Chica of Córdoba (Argentina, two lithological varieties of amphibolites associated with the La Cocha ultramafic body, crops out two kilometer south of the Bosque Alegre Astronomical Observatory. These varieties include non-pyroxene amphibolite composed of hornblende, plagioclase, titanite and opaque minerals, situated in the core of the ultramafic body folded structure. The second group is pyroxene amphibolites comprising hornblende, plagioclase, orthopyroxene (En, clino-pyroxene (Di and accessories including opaque minerals, apatite, more rarely titanite and zircon. This group appears in the ultramafic country rock represented by garnet

  12. The Resolved Asteroid Program - Size, shape, and pole of (52) Europa

    Science.gov (United States)

    Merline, W. J.; Drummond, J. D.; Carry, B.; Conrad, A.; Tamblyn, P. M.; Dumas, C.; Kaasalainen, M.; Erikson, A.; Mottola, S.; Ďurech, J.; Rousseau, G.; Behrend, R.; Casalnuovo, G. B.; Chinaglia, B.; Christou, J. C.; Chapman, C. R.; Neyman, C.

    2013-07-01

    With the adaptive optics (AO) system on the 10 m Keck-II telescope, we acquired a high quality set of 84 images at 14 epochs of asteroid (52) Europa on 2005 January 20, when it was near opposition. The epochs covered its 5.63 h rotation period and, by following its changing shape and orientation on the plane of sky, we obtained its triaxial ellipsoid dimensions and spin pole location. An independent determination from images at three epochs obtained in 2007 is in good agreement with these results. By combining these two data sets, along with a single epoch data set obtained in 2003, we have derived a global fit for (52) Europa of diameters a × b × c = (379 × 330 × 249) ± (16 × 8 × 10) km, yielding a volume-equivalent spherical-diameter of √abc3 =315±7km, and a prograde rotational pole within 7° of [RA; Dec] = [257°; +12°] in an Equatorial J2000 reference frame (Ecliptic: 255°; +35°). Using the average of all mass determinations available for (52) Europa, we derive a density of 1.5 ± 0.4 g cm-3, typical of C-type asteroids. Comparing our images with the shape model of Michalowski et al. (2004, Astron. Astrophys. 416, 353), derived from optical lightcurves, illustrates excellent agreement, although several edge features visible in the images are not rendered by the model. We therefore derived a complete 3-D description of (52) Europa's shape using the KOALA algorithm by combining our 18 AO imaging epochs with 4 stellar occultations and 49 lightcurves. We use this 3-D shape model to assess these departures from ellipsoidal shape. Flat facets (possible giant craters) appear to be less distinct on (52) Europa than on other C-types that have been imaged in detail, (253) Mathilde and (511) Davida. We show that fewer giant craters, or smaller largest-sized craters, is consistent with its expected impact history. Overall, asteroid (52) Europa is still well modeled as a smooth triaxial ellipsoid with dimensions constrained by observations obtained over

  13. Projeto educação em ciências com observatórios virtuais: a participação da Escola Moppe no período 2000-2003

    Science.gov (United States)

    Wuensche, C. A.; Gavioli, E.; Oliveira, A. L. P. R. S.; da Silva, C.; Cardoso, H. P.; Estácio, S.

    2003-08-01

    O projeto Educação em Ciências com Observatórios Virtuais foi concebido pelo Instituto Astronômico e Geofísico da USP, agregando diversas instituições de ensino e pesquisa no país para desenvolver competências diversas na educação fundamental, média e superior utilizando a astronomia como ferramenta multidisciplinar. Este trabalho descreve a participação da MOPPE, escola-piloto do INPE no projeto, no período de 2000-2003. Serão apresentadas 1) a criação de um clube de ciências (1999 a 2001) cujo tema foi a colonização de Marte e 2) a ementa de astronomia trabalhada com as 7a. e 8a. séries do ensino fundamental. A proposta do projeto Colonizando Marte foi estudar diversos aspectos de uma missão interplanetária e construir experiementos que permitissem quantificar esses aspectos. Os resultados obtidos incluiram apresentações nas SBPC Jovem em 2000 e 2001. Discutiremos também as ementas de astronomia trabalhadas desde 2001 e o envolvimento dos alunos com atividades ligadas a astronomia, fora da aula de ciências. A inclusão de astronomia no currículo das últimas séries motivou a participação de mais alunos culminando com a conquista de duas medalhas para alunos da 7a. série na Olimpiada Brasileira de Astronomia em 2002. Houve também um aumento no número de participantes na OBA 2003 e nos projetos de astronomia mais elaborados nas Feira de Ciências de 2001 e 2002. Destacamos em 2003 a inclusão da MOPPE no projeto TIE - Telescopes in Education - da NASA, que utiliza o telescópio do Observatório de Mount Wilson (EUA) para observações remotas em projetos pedagógicos para o ensino de astronomia.

  14. El Real Instituto y Observatorio de la Armada

    Directory of Open Access Journals (Sweden)

    Boloix Carlos-Roca, Rafael C.

    2002-10-01

    Full Text Available Not available

    Desde 1753, en que fue creado por el insigne marino Jorge Juany Santacilia, el Real Instituto y Observatorio de la Armada (ROA ha sido el núcleo de la investigación científica de la Armada, manteniendo hoy día un reconocido prestigio tanto a nivel nacional como internacional. El autor de este artículo, director del ROA, a través de una síntesis descriptiva de la estructura orgánica del centro en cuatro Secciones (Efemérides, Astronomía, Geofísica, y Hora, nos introduce en la evolución histórica de esta institución y en la amplia gama de actividades que desarrolla en la actualidad, participando en numerosos proyectos y foros internacionales, y manteniendo relaciones de colaboración permanente con organismos científicos similares de diversos países. Sus publicaciones de efemérides astronómicas, sus trabajos en geomagnetismo, sismología, seguimiento de satélites, astrofísica, metrología, etc. etc., así como el hecho de ser el depositario del Patrón Nacional de la unidad de tiempo, son el exponente de que el ROA continúa siendo un centro científico en plena actividad y pujanza, y en no pocas ocasiones la voz de España en el concierto internacional de estas ramas del conocimiento y de la investigación. Finaliza el artículo con una breve referencia a la Escuela de Estudios Superiores, vinculada al ROA desde su creación y que continúa con sus cursos de «estudios mayores» manteniendo vivo el espíritu científico de la Armada, mediante la formación de un selecto núcleo de oficiales en las áreas de ciencias Físico-Matemáticas, Astronomía y Geofísica, y en la preparación para los cursos de Ingeniería.

  15. Diagnosing the Source Region of a Solar Burst on 26 September 2011 by Using Microwave Type-III Pairs

    Science.gov (United States)

    Tan, B. L.; Karlický, M.; Mészárosová, H.; Kashapova, L.; Huang, J.; Yan, Y.; Kontar, E. P.

    2016-09-01

    We report a peculiar and interesting train of microwave Type-III pair bursts in the impulsive rising phase of a solar flare on 26 September 2011. The observations include radio spectrometers at frequencies of 0.80 - 2.00 GHz from the Ondřejov radiospectrograph in the Czech Republic (ORSC), hard X-ray from the Ramaty High-Energy Solar Spectroscopic Imager (RHESSI) and Gamma-Ray Burst Monitor onboard the Fermi Space Telescope (Fermi/GRB), EUV images from the Sun Watcher using APS detectors and image Processing instrument onboard the Project for Onboard Autonomy 2 (SWAP/PROBA2), and magnetograms from the Helioseismic and Magnetic Imager onboard the Solar Dynamic Observatory (SDO/HMI). By using a recently developed method (Tan et al., Res. Astron. Astrophys. 16, 82, 2016a), we diagnosed the plasma density, temperature, plasma- β, magnetic field near the source region, the energy of energetic electrons, and the distance between the acceleration region and the emission start sites of Type-III bursts. From the diagnostics, we find that i) The plasma density, temperature, magnetic field, and the distance between the acceleration region and the emission start sites have almost no obvious variations during the period of Type-III pair trains, while the energy of electrons has an obvious peak value that is consistent with the hard X-ray emission. ii) The plasma- β is much higher than unity, showing a highly dynamic process near the emission start site of Type-III bursts. iii) Although the reversed-slope Type-III branches drift more slowly by one order of magnitude than that of the normal Type-IIIs, the related descending and ascending electrons still could have energy of the same order of magnitude. These facts indicate that both the ascending and descending electrons are possibly accelerated by a similar mechanism and in a small source region. These diagnostics can help us to understand the physics in the source region of solar bursts.

  16. Developing the Planetary Science Virtual Observatory

    Science.gov (United States)

    Erard, Stéphane; Cecconi, Baptiste; Le Sidaner, Pierre; Henry, Florence; Chauvin, Cyril; Berthier, Jérôme; André, Nicolas; Génot, Vincent; Schmitt, Bernard; Capria, Teresa; Chanteur, Gérard

    2015-08-01

    In the frame of the Europlanet-RI program, a prototype Virtual Observatory dedicated to Planetary Science has been set up. Most of the activity was dedicated to the definition of standards to handle data in this field. The aim was to facilitate searches in big archives as well as sparse databases, to make on-line data access and visualization possible, and to allow small data providers to make their data available in an interoperable environment with minimum effort. This system makes intensive use of studies and developments led in Astronomy (IVOA), Solar Science (HELIO), and space archive services (IPDA).The current architecture connects existing data services with IVOA or IPDA protocols whenever relevant. However, a more general standard has been devised to handle the specific complexity of Planetary Science, e.g. in terms of measurement types and coordinate frames. This protocol, named EPN-TAP, is based on TAP and includes precise requirements to describe the contents of a data service (Erard et al Astron & Comp 2014). A light framework (DaCHS/GAVO) and a procedure have been identified to install small data services, and several hands-on sessions have been organized already. The data services are declared in standard IVOA registries. Support to new data services in Europe will be provided during the proposed Europlanet H2020 program, with a focus on planetary mission support (Rosetta, Cassini…).A specific client (VESPA) has been developed at VO-Paris (http://vespa.obspm.fr). It is able to use all the mandatory parameters in EPN-TAP, plus extra parameters from individual services. A resolver for target names is also available. Selected data can be sent to VO visualization tools such as TOPCAT or Aladin though the SAMP protocol.Future steps will include the development of a connection between the VO world and GIS tools, and integration of heliophysics, planetary plasma and reference spectroscopic data.The EuroPlaNet-RI project was funded by the European

  17. Laboratory and theoretical work in the service of planetary atmospheric research

    Science.gov (United States)

    Coustenis, Athena

    2015-08-01

    . Astron. Astrophys. Rev. 21, #63. [5] Encrenaz, T., et al., 2014. Experimental Astronomy, DOI: 10.1007/s10686-014-9415-0.

  18. Orbital and physical characteristics of meter-scale impactors from airburst observations

    Science.gov (United States)

    Brown, P.; Wiegert, P.; Clark, D.; Tagliaferri, E.

    2016-03-01

    We have analyzed the orbits and ablation characteristics in the atmosphere of 59 Earth-impacting fireballs, produced by meteoroids 1 m in diameter or larger, described here as meter-scale. Using heights at peak luminosity as a proxy for strength, we determine that there is roughly an order of magnitude spread in strengths of the population of meter-scale impactors at the Earth. We use fireballs producing recovered meteorites and well documented fireballs from ground-based camera networks to calibrate our ablation model interpretation of the observed peak height of luminosity as a function of speed. The orbits and physical strength of these objects are consistent with the majority being asteroidal bodies originating from the inner main asteroid belt. This is in contrast to earlier suggestions by Ceplecha (Ceplecha, Z. [1994]. Astron. Astrophys. 286, 967-970) that the majority of meter-tens of meter sized meteoroids are "… cometary bodies of the weakest known structure". We find a lower limit of ∼10-15% of our objects have a possible cometary (Jupiter-Family comet and/or Halley-type comet) origin based on orbital characteristics alone. Only half this number, however, also show evidence for weaker than average structure. Two events, Sumava and USG 20131121, have exceptionally high (relative to the remainder of the population) heights of peak brightness. These are physically most consistent with high microporosity objects, though both were on asteroidal-type orbits. We also find three events, including the Oct 8, 2009 airburst near Sulawesi, Indonesia, which display comparatively low heights of peak brightness, consistent with strong monolithic stones or iron meteoroids. Based on orbital similarity, we find a probable connection among several events in our population with the Taurid meteoroid complex; no other major meteoroid streams show probable linkages to the orbits of our meter-scale population. Our impactors cover almost four orders of magnitude in mass, but

  19. CALIFA, the Calar Alto Legacy Integral Field Area survey. IV. Third public data release

    Science.gov (United States)

    Sánchez, S. F.; García-Benito, R.; Zibetti, S.; Walcher, C. J.; Husemann, B.; Mendoza, M. A.; Galbany, L.; Falcón-Barroso, J.; Mast, D.; Aceituno, J.; Aguerri, J. A. L.; Alves, J.; Amorim, A. L.; Ascasibar, Y.; Barrado-Navascues, D.; Barrera-Ballesteros, J.; Bekeraitè, S.; Bland-Hawthorn, J.; Cano Díaz, M.; Cid Fernandes, R.; Cavichia, O.; Cortijo, C.; Dannerbauer, H.; Demleitner, M.; Díaz, A.; Dettmar, R. J.; de Lorenzo-Cáceres, A.; del Olmo, A.; Galazzi, A.; García-Lorenzo, B.; Gil de Paz, A.; González Delgado, R.; Holmes, L.; Iglésias-Páramo, J.; Kehrig, C.; Kelz, A.; Kennicutt, R. C.; Kleemann, B.; Lacerda, E. A. D.; López Fernández, R.; López Sánchez, A. R.; Lyubenova, M.; Marino, R.; Márquez, I.; Mendez-Abreu, J.; Mollá, M.; Monreal-Ibero, A.; Ortega Minakata, R.; Torres-Papaqui, J. P.; Pérez, E.; Rosales-Ortega, F. F.; Roth, M. M.; Sánchez-Blázquez, P.; Schilling, U.; Spekkens, K.; Vale Asari, N.; van den Bosch, R. C. E.; van de Ven, G.; Vilchez, J. M.; Wild, V.; Wisotzki, L.; Yıldırım, A.; Ziegler, B.

    2016-10-01

    This paper describes the third public data release (DR3) of the Calar Alto Legacy Integral Field Area (CALIFA) survey. Science-grade quality data for 667 galaxies are made public, including the 200 galaxies of the second public data release (DR2). Data were obtained with the integral-field spectrograph PMAS/PPak mounted on the 3.5 m telescope at the Calar Alto Observatory. Three different spectral setups are available: i) a low-resolution V500 setup covering the wavelength range 3745-7500 Å (4240-7140 Å unvignetted) with a spectral resolution of 6.0 Å (FWHM) for 646 galaxies, ii) a medium-resolution V1200 setup covering the wavelength range 3650-4840 Å (3650-4620 Å unvignetted) with a spectral resolution of 2.3 Å (FWHM) for 484 galaxies, and iii) the combination of the cubes from both setups (called COMBO) with a spectral resolution of 6.0 Å and a wavelength range between 3700-7500 Å (3700-7140 Å unvignetted) for 446 galaxies. The Main Sample, selected and observed according to the CALIFA survey strategy covers a redshift range between 0.005 and 0.03, spans the color-magnitude diagram and probes a wide range of stellar masses, ionization conditions, and morphological types. The Extension Sample covers several types of galaxies that are rare in the overall galaxy population and are therefore not numerous or absent in the CALIFA Main Sample. All the cubes in the data release were processed using the latest pipeline, which includes improved versions of the calibration frames and an even further improved image reconstruction quality. In total, the third data release contains 1576 datacubes, including ~1.5 million independent spectra. Based on observations collected at the Centro Astronómico Hispano Alemán (CAHA) at Calar Alto, operated jointly by the Max-Planck-Institut für Astronomie (MPIA) and the Instituto de Astrofísica de Andalucía (CSIC).The spectra are available at http://califa.caha.es/DR3

  20. Departure from the constant-period ephemeris for the transiting exoplanet WASP-12

    Science.gov (United States)

    Maciejewski, G.; Dimitrov, D.; Fernández, M.; Sota, A.; Nowak, G.; Ohlert, J.; Nikolov, G.; Bukowiecki, Ł.; Hinse, T. C.; Pallé, E.; Tingley, B.; Kjurkchieva, D.; Lee, J. W.; Lee, C.-U.

    2016-04-01

    Aims: Most hot Jupiters are expected to spiral in toward their host stars because the angular momentum of the orbital motion is transferred to the stellar spin. Their orbits can also precess as a result of planet-star interactions. Calculations show that both effects might be detected for the very-hot exoplanet WASP-12 b using the method of precise transit-timing over a time span of about 10 yr. Methods: We acquired new precise light curves for 29 transits of WASP-12 b, spannning four observing seasons from November 2012 to February 2016. New mid-transit times, together with those from the literature, were used to refine the transit ephemeris and analyze the timing residuals. Results: We find that the transit times of WASP-12 b do not follow a linear ephemeris with a 5σ confidence level. They may be approximated with a quadratic ephemeris that gives a change rate in the orbital period of (-2.56 ± 0.40) × 10-2 s yr-1. The tidal quality parameter of the host star was found to be equal to 2.5 × 105, which is similar to theoretical predictions for Sun-like stars. We also considered a model in which the observed timing residuals are interpreted as a result of the apsidal precession. We find, however, that this model is statistically less probable than the orbital decay. Partly based on (1) data collected with the Nordic Optical Telescope, operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway, and Sweden, in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias, (2) observations made at the Centro Astronómico Hispano Alemán (CAHA), operated jointly by the Max-Planck Institut für Astronomie and the Instituto de Astrofísica de Andalucía (CSIC), and (3) data collected with telescopes at the Rozhen National Astronomical Observatory.The light curves are available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/588/L

  1. The central dynamics of M3, M13, and M92: stringent limits on the masses of intermediate-mass black holes

    Science.gov (United States)

    Kamann, S.; Wisotzki, L.; Roth, M. M.; Gerssen, J.; Husser, T.-O.; Sandin, C.; Weilbacher, P.

    2014-06-01

    We used the PMAS integral field spectrograph to obtain large sets of radial velocities in the central regions of three northern Galactic globular clusters: M3, M13, and M92. By applying the novel technique of crowded field 3D spectroscopy, we measured radial velocities for about 80 stars within the central ~10″ of each cluster. These are by far the largest spectroscopic datasets obtained in the innermost parts of these clusters up to now. To obtain kinematical data across the whole extent of the clusters, we complement our data with measurements available in the literature. We combine our velocity measurements with surface brightness profiles to analyse the internal dynamics of each cluster using spherical Jeans models, and investigate whether our data provide evidence for an intermediate-mass black hole in any of the clusters. The surface brightness profiles reveal that all three clusters are consistent with a core profile, although shallow cusps cannot be excluded. We find that spherical Jeans models with a constant mass-to-light ratio provide a good overall representation of the kinematical data. A massive black hole is required in none of the three clusters to explain the observed kinematics. Our 1σ (3σ) upper limits are 5300 M⊙ (12 000 M⊙) for M3, 8600 M⊙ (13 000 M⊙) for M13, and 980 M⊙ (2700 M⊙) for M92. A puzzling circumstance is the existence of several potential high velocity stars in M3 and M13, as their presence can account for the majority of the discrepancies that we find in our mass limits compared to M92. Based on observations collected at the Centro Astronómico Hispano-Alemán (CAHA) at Calar Alto, operated jointly by the Max-Planck Institut für Astronomie and the Instituto de Astrofísica de Andalucía (CSIC).Appendices are available in electronic form at http://www.aanda.orgTables D.1 to D.6 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc

  2. Follow-up spectroscopic observations of HD 107148 B: A new white dwarf companion of an exoplanet host star

    Science.gov (United States)

    Mugrauer, M.; Dinçel, B.

    2016-07-01

    We report on our follow-up spectroscopy of HD 1071478 B, a recently detected faint co-moving companion of the exoplanet host star HD 107148 A. The companion is separated from its primary star by about 35 arcsec (or 1790 AU of projected separation) and its optical and near infrared photometry is consistent with a white dwarf, located at the distance of HD 107148 A. In order to confirm the white dwarf nature of the co-moving companion, we obtained follow-up spectroscopic observations of HD 107148 B with CAFOS at the CAHA 2.2 m telescope. According to our CAFOS spectroscopy HD 107148 B is a DA white dwarf with an effective temperature in the range between 5900 and 6400 K. The properties of HD 107148 B can further be constrained with the derived effective temperature and the known visual and infrared photometry of the companion, using evolutionary models of DA white dwarfs. We obtain for HD 107148 B a mass of 0.56±0.05 M_⊙, a luminosity of (2.0±0.2)×10-4 L_⊙, log g [cm s-2])=7.95±0.09, and a cooling age of 2100±270 Myr. With its white dwarf companion the exoplanet host star HD 107148 A forms an evolved stellar system, which hosts at least one exoplanet. So far, only few of these evolved systems are known, which represent only about 5 % of all known exoplanet host multiple stellar systems. HD 107148 B is the second confirmed white dwarf companion of an exoplanet host star with a projected separation to its primary star of more than 1000 AU. Based on observations collected at the Centro Astronómico Hispano Alemán (CAHA) at Calar Alto, operated jointly by the Max-Planck Institut für Astronomie and the Instituto de Astrofísica de Andalucía (CSIC).

  3. First survey of Wolf-Rayet star populations over the full extension of nearby galaxies observed with CALIFA

    Science.gov (United States)

    Miralles-Caballero, D.; Díaz, A. I.; López-Sánchez, Á. R.; Rosales-Ortega, F. F.; Monreal-Ibero, A.; Pérez-Montero, E.; Kehrig, C.; García-Benito, R.; Sánchez, S. F.; Walcher, C. J.; Galbany, L.; Iglesias-Páramo, J.; Vílchez, J. M.; González Delgado, R. M.; van de Ven, G.; Barrera-Ballesteros, J.; Lyubenova, M.; Meidt, S.; Falcon-Barroso, J.; Mast, D.; Mendoza, M. A.; Califa Collaboration

    2016-08-01

    binary star channel (which could extend theWR phase up to 10 Myr), fast rotation, or other physical processes that cause the loss of observed Lyman continuum photons, very likely affect the derived WR properties, and hence should be considered when modelling the evolution of massive stars. Based on observations collected at the Centro Astronómico Hispano-Alemán (CAHA) at Calar Alto, operated jointly by the Max-Planck Institut für Astronomie and the Instituto de Astrofísica de Andalucía (CSIC).

  4. Evaluación de la escala Borg de esfuerzo percibido aplicada a la rehabilitación cardiaca Instrument evaluation of Borg's perceived exertion scale in cardiac rehabilitation

    Directory of Open Access Journals (Sweden)

    Natalie Burkhalter

    1996-12-01

    Full Text Available La escala Borg de esfuerzo percibido mide la gama entera del esfuerzo que el individuo percibe al hacer ejercicio. Esta escala da criterios para hacerle ajustes a la intensidad de ejercicio, o sea, a la carga de trabajo, y así pronosticar y dictaminar las diferentes intensidades del ejercicio en los deportes y en la rehabilitación médica (BORG, 1982. También se puede usar tanto en el atletismo, en la astronáutica, la industria y ambientes militares, como en las situaciones cotidianas. El concepto del esfuerzo percibido es una valoración subjetiva que indica la opinión del sujeto respecto a la intensidad del trabajo realizado (MORGAN, 1973. El sujeto que hace el ejercicio debe asignar un número del 1 al 20, para representar la sensación subjetiva de la cantidad de trabajo desempeñado. La escala es una herramienta valiosa dentro del ámbito del desempeño humano, en que a menudo la consideración importante no es tanto "lo que haga el individuo" "sino" "lo que cree que hace" (MORGAN, 1973.Borg's perceived exertion scale measures the extent of perceived exertion which a person experiences during exercise. The perceived exertion scale is used to adjust exercise intensity (workload for predictions and prescriptions of exercise intensities in sports and medical rehabilitation (BORG, 1982. In addition, Borg's scale can be used in the athletic arena, space, industry, military settings, or under everyday circumstances. The concept of perceived exertion is a subjective rating, indicating the subject's opinion about the intensity of the work being performed (MORGAN, 1973. The task of exercising subjects is to assign a number (from 1-20 to represent the subjective sensation of the amount of work being performed. This is a valuable tool in human performance setting, where an important consideration is not "what the individual is doing, but what he thinks and is doing" (MORGAN, 1973.

  5. The Binary Fission Model for the Formation of the Pluto system

    Science.gov (United States)

    Prentice, Andrew

    2016-10-01

    The ratio F of the mass of Pluto (P) to Charon (C), viz. F ≈ 8:1, is the largest ratio of any planet-satellite pair in the solar system. Another measure of the PC binary is its normalized angular momentum density J (see McKinnon 1989). Analysis of astrometric data (Brozovic et al 2015) acquired before the New Horizons (NH) arrival at Pluto and new measurements made by NH (Stern et al 2015) show that J = 0.39. Yet these F & J values are ones expected if the PC binary had formed by the rotational fission of a single liquid mass (Darwin 1902; Lyttleton 1953). At first glance, therefore, the fission model seems to be a viable model for the formation of the Pluto system. In fact, Prentice (1993 Aust J Astron 5 111) had used this model to successfully predict the existence of several moons orbiting beyond Charon, before their discovery in 2005-2012. The main problem with the fission model is that the observed mean density of Charon, namely 1.70 g/cm3, greatly exceeds that of water ice. Charon thus could not have once been a globe of pure water. Here I review the fission model within the framework of the modern Laplacian theory of solar system origin (Prentice 1978 Moon Planets 19 341; 2006 PASA 23 1) and the NH results. I assume that Pluto and Charon were initially a single object (proto-Pluto [p-P]) which had condensed within the same gas ring shed by the proto-solar cloud at orbital distance ~43 AU, where the Kuiper belt was born. The temperature of this gas ring is 26 K and the mean orbit pressure is 1.3 × 10-9 bar. After the gas ring is shed, chemical condensation takes place. The bulk chemical composition of the condensate is anhydrous rock (mass fraction 0.5255), graphite (0.0163), water ice (0.1858), CO2 ice (0.2211) and methane ice (0.0513). Next I assume that melting of the ices in p-P takes place through the decay of short-lived radioactive nuclides, thus causing internal segregation of the rock & graphite. Settling of heavy grains to the centre lowers the

  6. HST Observations of Spokes in Saturn's B Ring

    Science.gov (United States)

    McGhee, C. A.; French, R. G.

    2002-09-01

    Spokes, the transient streaks on Saturn's B ring, were revealed during the Voyager flybys. Their photometric properties have been interpreted in terms of small dust particles that become charged and interact with Saturn's magnetic field and plasma environment. From an examination of seven spokes in the Voyager images, Doyle and Grün (1990, Icarus 85, 168--190) concluded that the dust particles were approximately 0.6 μ m in radius with a fairly narrow size distribution. As part of a long--term study of Saturn's rings using WFPC2 as well as archival HST data, we have measured the photometric properties of spokes visible in a substantial number of images, particularly at low ring tilt angle. The high photometric accuracy of WFPC2 and extensive spectral coverage ranging from 255 to 973 nm have enabled us to extend Doyle and Grün's analysis over a much broader range of wavelengths than the blue end of the spectrum to which the Voyager cameras were sensitive. We searched for spokes in over 300 HST images from 1994 to 2002, and detected over 20 spokes in the full set of observations. They are visible on both east and west ansae, though they are generally more prominent on the east (or ``morning") ansa (cf. Porco and Danielson 1982, Astron. J. 87, 826--833). We follow the technique of Doyle and Grün (1990), where we model Mie particle extinction efficiency using a Hansen--Hovenier particle size distribution with an effective radius r eff and a size distribution variance b. To date, we have performed photometry on four spokes to determine the extinction efficiency Q ext as a function of size parameter 2π r/λ . >From our fits to the color dependence of the spoke contrast, which sample both the rising and falling slopes of the Mie scattering peak, we are able to determine tight constraints on both r eff and b. We obtain r eff ~ 0.51-0.56\\ μ m and variance b ~ 0.1-0.15. This strongly reinforces the conclusion that the particles comprising the spokes are very fine dust

  7. Investigation of a transiting planet candidate in Trumpler 37: An astrophysical false positive eclipsing spectroscopic binary star

    Science.gov (United States)

    Errmann, R.; Torres, G.; Schmidt, T. O. B.; Seeliger, M.; Howard, A. W.; Maciejewski, G.; Neuhäuser, R.; Meibom, S.; Kellerer, A.; Dimitrov, D. P.; Dincel, B.; Marka, C.; Mugrauer, M.; Ginski, Ch.; Adam, Ch.; Raetz, St.; Schmidt, J. G.; Hohle, M. M.; Berndt, A.; Kitze, M.; Trepl, L.; Moualla, M.; Eisenbeiß, T.; Fiedler, S.; Dathe, A.; Graefe, Ch.; Pawellek, N.; Schreyer, K.; Kjurkchieva, D. P.; Radeva, V. S.; Yotov, V.; Chen, W. P.; Hu, S. C.-L.; Wu, Z.-Y.; Zhou, X.; Pribulla, T.; Budaj, J.; Vaňko, M.; Kundra, E.; Hambálek, Ľ.; Krushevska, V.; Bukowiecki, Ł.; Nowak, G.; Marschall, L.; Terada, H.; Tomono, D.; Fernandez, M.; Sota, A.; Takahashi, H.; Oasa, Y.; Briceño, C.; Chini, R.; Broeg, C. H.

    We report our investigation of the first transiting planet candidate from the YETI project in the young (˜4 Myr old) open cluster Trumpler 37. The transit-like signal detected in the lightcurve of F8V star 2M21385603+5711345 repeats every 1.364894±0.000015 days, and has a depth of 54.5±0.8 mmag in R. Membership in the cluster is supported by its mean radial velocity and location in the color-magnitude diagram, while the Li diagnostic and proper motion are inconclusive in this regard. Follow-up photometric monitoring and adaptive optics imaging allow us to rule out many possible blend scenarios, but our radial-velocity measurements show it to be an eclipsing single-lined spectroscopic binary with a late-type (mid-M) stellar companion, rather than one of planetary nature. The estimated mass of the companion is 0.15-0.44 M⊙. The search for planets around very young stars such as those targeted by the YETI survey remains of critical importance to understand the early stages of planet formation and evolution. Based in part on data collected at Subaru Telescope, which is operated by the National Astronomical Observatory of Japan. Some of the data presented herein were obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration (Proposal ID H215Hr). The Observatory was made possible by the generous financial support of the W.M. Keck Foundation. Based on observations obtained with telescopes of the University Observatory Jena, which is operated by the Astrophysical Institute of the Friedrich-Schiller-University. Based on observations collected at the Centro Astronómico Hispano Alemán (CAHA) at Calar Alto, operated jointly by the Max-Planck Institut für Astronomie and the Instituto de Astrofísica de Andalucía (CSIC, Proposal IDs H10-3.5-015 and H10-2.2-004). Some of the observations reported here were obtained at

  8. Induction Linac Pulsers

    International Nuclear Information System (INIS)

    The pulsers used in most of the induction linacs evolved from the very large body of work that was done in the U.S. and Great Britain during the development of the pulsed magnetron for radar. The radar modulators started at ∼100 kW and reached >10 MW by 1945. A typical pulse length was 1 μs at a repetition rate of 1,000 pps. A very comprehensive account of the modulator development is Pulse Generators by Lebacqz and Glasoe, one of the Radiation Laboratory Series. There are many permutations of possible modulators, two of the choices being tube type and line type. In earlier notes I wrote that technically the vacuum tube pulser met all of our induction linac needs, in the sense that a number of tubes, in series and parallel if required, could produce our pulses, regulate their voltage, be useable in feed-forward correctors, and provide a low source impedance. At a lower speed, an FET array is similar, and we have obtained and tested a large array capable of >10 MW switching. A modulator with an electronically controlled output only needs a capacitor for energy storage and in a switched mode can transfer the energy from the capacitor to the load at high efficiency. Driving a full size Astron induction core and a simulated resistive 'beam load' we achieved >50% efficiency. These electronically controlled output pulses can produce the pulses we desire but are not used because of their high cost. The second choice, the line type pulser, visually comprises a closing switch and a distributed or a lumped element transmission line. The typical switch cannot open or stop conducting after the desired pulse has been produced, and consequently all of the initially stored energy is dissipated. This approximately halves the efficiency, and the original cost estimating program LIACEP used this factor of two, even though our circuits are usually worse, and even though our inveterate optimists often omit it. The 'missing' energy is that which is reflected back into the line from

  9. Mass decomposition of SLACS lens galaxies in Weyl conformal gravity

    Science.gov (United States)

    Potapov, Alexander A.; Izmailov, Ramil N.; Nandi, Kamal K.

    2016-06-01

    We study here, using the Mannheim-Kazanas solution of Weyl conformal theory, the mass decomposition in the representative subsample of 57 early-type elliptical lens galaxies of the Sloan Lens Advanced Camera for Surveys (SLACS) on board the Hubble Space Telescope. We begin by showing that the solution need not be an exclusive solution of conformal gravity but can also be viewed as a solution of a class of f (R ) gravity theories coupled to nonlinear electrodynamics thereby rendering the ensuing results more universal. Since lensing involves light bending, we shall first show that the solution adds to Schwarzschild light bending caused by the luminous mass (M*) a positive contribution +γ R contrary to the previous results in the literature, thereby resolving a long-standing problem. The cause of the error is critically examined. Next, applying the expressions for light bending together with an input equating Einstein and Weyl angles, we develop a novel algorithm for separating the luminous component from the total lens mass (luminous+dark ) within the Einstein radius. Our results indicate that the luminous mass estimates differ from the observed total lens masses by a linear proportionality factor across the subsample, which qualitatively agrees with the common conclusion from a number of different simulations in the literature. In quantitative detail, we observe that the ratios of luminous over total lens mass (f*) within the Einstein radius of individual galaxies take on values near unity, many of which remarkably fall inside or just marginally outside the specified error bars obtained from a simulation based on the Bruzual-Charlot stellar population synthesis model together with the Salpeter initial mass function favored on the ground of metallicity [Grillo et al., Astron. Astrophys. 501, 461 (2009)]. We shall also calculate the average dark matter density ⟨ρ⟩ av of individual galaxies within their respective Einstein spheres. To our knowledge, the present

  10. Discussion on the spectral coherence between planetary, solar and climate oscillations: a reply to some critiques

    Science.gov (United States)

    Scafetta, Nicola

    2014-12-01

    oscillations is confirmed at the following periods: 5.2 year, 5.93 year, 6.62 year, 7.42 year, 9.1 year (main lunar tidal cycle), 10.4 year (related to the 9.93-10.87-11.86 year solar cycle harmonics), 13.8-15.0 year, ˜20 year, ˜30 year and ˜61 year, 103 year, 115 year, 130 year, 150 year and about 1000 year. This work responds to the critiques of Cauquoin et al. (Astron. Astrophys. 561:A132, 2014), who ignored alternative planetary theories of solar variations, and of Holm (J. Atmos. Sol. Terr. Phys. 110-111:23-27, 2014a), who used inadequate physical and time frequency analyses of the data.

  11. Sistemas Correctores de Campo Para EL Telescopio Cassegrain IAC80

    Science.gov (United States)

    Galan, M. J.; Cobos, F. J.

    1987-05-01

    El proyecto de instrumentación de mayor importancia que ha tenido el Instituto de Astrofisica de Canarias en los últimos afios ha sido el diseflo y construcción del te1escopio IAC8O. Este requería del esfuerzo con junto en mec´nica, óptica y electrónica, lo que facilitó la estructuración y el crecimiento de los respectivos grupos de trabajo, que posteriormente se integraron en departamentos En su origen (1977), el telescopio IAC80 fue concebido como un sistema clásico tipo Cassegrain, con una razón focal F/i 1.3 para el sistema Casse grain y una razón focal F/20 para el sistema Coudé. Posteriormente, aunque se mantuvo la filosofia de que el sistema básico fuera el F/11.3, se consideró conveniente el diseño de secundarios para razones focales F/16 y F/32, y se eliminó el de F/20. Sin embargo, dada la importancia relativa que un foco estrictamente fotográfico tiene en un telescopio moderno, diseñado básicamente para fotometría fotoeléctrica y con un campo util mínimamente de 40 minutos de arco, se decídió Ilevar a cabo el diseño de un secundario F/8 con un sistema corrector de campo, pero que estuviera formado únicamente por lentes con superficies esféricas para que asl su construcción fuera posible en España ó en México. La creciente utilización de detectores bidimensionales para fines de investigación astron6mica y la viabilidad de que en un futuro cercano éstos tengan un área sensible cada vez mayor, hicieron atractiva la idea de tener diseñado un sistema corrector de campo para el foco primario (F/3), con un campo útil mínimo de un grado, y también con la limitante de que sus componentes tuvieron sólamente supérficies esféricas. Ambos diseños de los sis-temas correctores de campo se llevaron a cabo, en gran medida, como parte de un proyecto de colaboración e intercambio en el área de diseño y evaluación de sistemas ópticos.

  12. Comportamiento del Helio en estrellas químicamente peculiares

    Science.gov (United States)

    Malaroda, S. M.; López García, Z.; Leone, F.; Catalano, F.

    Las estrellas químicamente peculiares (CP) se caracterizan por tener deficiencias y sobreabundancias de algunos elementos químicos de hasta 106 veces la abundancia solar. Además presentan variaciones en las líneas espectrales. Se piensa que ello se debe a que los campos magnéticos presentes en este tipo de estrellas son principalmente dipolares, con un eje de simetría diferente del eje de rotación. La distribución de los elementos sobreabundantes y deficientes no es homogénea sobre la superficie estelar y las variaciones observadas serían una consecuencia directa de la rotación estelar. Entre los elementos con abundancia anómala se encuentra el Helio, cuyas líneas tienen intensidades que no son consistentes con una abundancia normal, que no puede ser determinada del modo usual, o sea, considerando una atmósfera con composición solar. Con el fin de determinar la abundancia de este elemento, se inició un estudio de estrellas anómalas de Helio, Hew y He strong. Además se determinarán las abundancias de otros elementos anómalos como ser el Si, Cr, Mg, Mn y Fe. Las mismas se determinan del modo tradicional, o sea: a) medida de los anchos equivalentes de las líneas de los distintos elementos analizados; b) adopción de la temperatura efectiva, gravedad y abundancia del Helio; c) cálculo del modelo de atmósfera d) comparación con las observaciones y reinicio de un proceso iterativo hasta lograr un acuerdo entre todos los parámetros analizados. Las observaciones se llevaron a cabo en el Complejo Astronómico El Leoncito. Se observaron setenta y ocho estrellas anómalas de Helio. En este momento se está procediendo a calcular las abundancias correspondientes a los distintos elementos químicos. Para ello se hace uso de los modelos de Kurucz, ATLAS9. Los cálculos NLTE de las líneas de Helio se llevan a cabo con el programa MULTI y se compararán con los realizados con el programa WIDTH9 de Kurucz (LTE), con el objeto de resaltar la importancia de

  13. Simulação de ejeções de massa coronal

    Science.gov (United States)

    Corsini, M. A.; Silva, A. V. R.

    2003-08-01

    Ejeções de massa coronal (EMC) são bolhas gigantes de gás permeadas por campos magnéticos que são ejetadas do Sol durante um período de várias horas. Caso estas ejeções atinjam a Terra, geralmente, causam uma série de distúrbios às comunicações de longa distância e navegação, além de danos a satélites e transformadores. Portanto, é desejável que sejamos capazes de prever quando estas ejeções atingirão a Terra. Para tanto, é necessário um bom entendimento dos mecanismos causadores das ejeções e, principalmente, de como se dá a propagação das EMC e sua interação com o vento solar que permeia o meio interplanetário. Nesse sentido foi desenvolvido um programa computacional para resolver as equações MHD (Magneto-Hidro-Dinâmica) que regem a evolução das EMC. Primeiramente foram estabelecidas as condições necessárias para descrever o vento solar, no estado estacionário, que permeia todo o meio interplanetário. Num primeiro momento, resolveu-se o sistema de equações para o caso do vento isotérmico, conhecida como a solução de Parker, a fim de testarmos o modelo. Então, foi considerado o caso do vento solar com temperatura variável no meio interplanetário. Este resultado foi utilizado como a base de nosso sistema em seu instante inicial. Posteriormente foram feitas as considerações necessárias para descrever a propagação da Ejeção de Massa Coronal. As EMC foram simuladas como um aumento de densidade e temperatura local na coroa solar. A órbita e a posição da Terra foram incluídas no sistema. Os dados gerados possibilitaram uma análise da evolução da EMC pelo meio interplanetário até encontrar-se com a Terra. Os perfis de densidade e temperatura a 1 Unidade Astronômica são comparados com os dados de satélites reportados na literatura.

  14. Pilot Search for 54-MHz Maser Emission from Interstellar Hydroxyl Using LOFAR

    Science.gov (United States)

    Hoffman, Ian M.; Heald, G.; Oonk, R.; McKean, J.; Mol, J.; Hessels, J.; Toribio, C.; LOFAR Collaboration

    2014-01-01

    We present the results of the most sensitive search to date for the two 54-MHz spectral lines of the hydroxyl (OH) molecule. These are the preliminary results of a larger, planned observational campaign. The splitting of the rotational ground state of the hydroxyl molecule gives rise to the four familiar 1.7-GHz transitions by which OH is known in the interstellar medium. There are also two magnetic-dipole transitions among these states at frequencies of 53.2 MHz and 55.1 MHz. These 54-MHz transitions have never been detected astronomically. Because of the relative weakness of the magnetic-dipole emission process, it is expected that only maser emission will generate a detectable 54-MHz signal. Two previous searches have been conducted by other authors with other instruments toward Galactic sources of known 1720-MHz OH maser emission: three sources were searched at 55.1 MHz and two other sources were searched at 53.2 MHz, resulting in upper limits of approximately 30 Jy for spectral channels of 2 km/s in width. In preparation for our future observational campaign that will apply the unprecedented sensitivity of LOFAR to the search for 54-MHz OH emission, we conducted a pilot project using six hours of Commissioning Time. These observations employed 21 48-element stations and produced a spectral resolution of approximately 0.5 km/s for both the 53.2- and 55.1-MHz lines. This spectral resolution is a considerable improvement over previous searches since it is suitable both for resolving the characteristically narrow width of maser lines and for identifying radiofrequency interference. In our pilot observations, no emission was detected at either frequency with an upper limit of approximately 3 Jy. We observed the Galactic sources W75N and W3(OH), neither of which have been searched previously at either frequency. We discuss the astrophysical implications of these sensitive non-detections. LOFAR, the Low Frequency Array designed and constructed by ASTRON, has

  15. Descripción del coronógrafo a ser instalado en Argentina (MICA)

    Science.gov (United States)

    Stenborg, G.; Francile, C.; Schwenn, R.; Epple, A.; Rovira, M.

    El ``Coronógrafo de espejo para Argentina'' es un telescopio solar terrestre a ser colocado en el Observatorio Astronómico Félix Aguilar (El Leoncito), antes de finalizar 1996, como parte de un programa de ciencia bilateral entre Alemania y Argentina. Eclipses fotográficos de alta resolución han revelado que la corona solar es altamente estructurada y variable. De hecho, está contínuamente deformada y moldeada por los movimientos convectivos de los extremos de los arcos magnéticos en la fotosfera, estando, en muchas oportunidades, afectada por explosivas liberaciones de energía. MICA, en conjunción con otros telescopios solares espaciales y terrestres, tratará de contribuir al entendimiento de cuestiones fundamentales de la física solar. Entre ellas: cómo la corona está siendo calentada, dónde y cómo el viento solar es acelerado, qué causa los transitorios coronales, etc. Para ello investigará la distribución de los parámetros del plasma y su evolución con el tiempo, la estructura espacial de la corona en fina y gran escala, procesos que ocurren en los transitorios coronales y factores que los disparan, etc. Para responder a estas cuestiones MICA observará la atmósfera solar por sobre el limbo entre 1.1 y 2 radios solares aproximadamente, usando un nuevo tipo de sistema coronográfico que permite suprimir el brillo del disco solar suficientemente bien, tomando las imágenes con una cámara CCD de 1024x1024 pixels, codificada en 12 bits, pudiendo el mismo ser operado en forma remota. En la presente exposición describiremos las características del instrumento, cómo será controlado y qué esperamos observar basados en las imágenes obtenidas por los telescopios de similares características LASCO C1 a bordo del SOHO y PICO (ubicado en el Observatorio de Pic du Midi, Francia).

  16. Espectroscopia de candidatos a remanescentes de aglomerados abertos

    Science.gov (United States)

    Pavani, D. B.; Bica, E.; Ahumada, A. V.; Clariá, J. J.

    2003-08-01

    A pesquisa sobre remanescentes de aglomerados abertos tem despertado grande interesse. Seguindo esta tendência encontramos estudos teóricos e observacionais. Os primeiros baseiam-se em simulações numéricas buscando determinar fração de binárias e distâncias galatocêntricas, tempo de vida e conteúdo estelar. Estes estão relacionados à função inicial de massa e densidade de estrelas, ou seja, se ricos ou pobremente povoados, compactos ou esparsos. No caso observacional procuram-se identificar os remanescentes considerando-se que trazem estas assinaturas de seus percursores. No presente estudo empregamos espectroscopia para analisar oito concentrações pobremente povoadas, previamente classificadas como aglomerados abertos, sendo sete compactas e uma esparsa. As observações foram obtidas através do telescópio de 2,15 m do CASLEO em San Juan, Argentina, em turnos entre 2001 e 2003. Utilizamos uma câmara CCD contendo um chip Tektronics de 1024X1024 pixeis aliado a um espectrógrafo REOSC. O domínio espectral vai de 3700 a 7000 Å. As reduções foram realizadas no Observatório Astronômico de Córdoba (Argentina) usando pacotes IRAF padrões. Determinamos idades, avermelhamentos e tipos espectrais através de comparações com biblioteca de estrelas e de aglomerados. Em alguns casos nossos espectros estavam dominados por estrelas individuais às quais determinamos seus tipos espectrais. Aos oito objetos adicionamos mais cinco da literatura recente analisados via espectro ou diagrama cor-magnitude. O histograma resultante contém idades típicas entre 0.5 e 3 Ganos. Considerando que predominantemente estes objetos encontram-se na vizinhança solar e, portanto, não cruzaram muitas vezes o plano Galático esperamos que a diferença no tempo necessário para dissolução destes prováveis remanescentes seja em função de diferentes massas iniciais.

  17. Kn 26, a new quadrupolar planetary nebula

    Science.gov (United States)

    Guerrero, M. A.; Miranda, L. F.; Ramos-Larios, G.; Vázquez, R.

    2013-03-01

    Once classified as an emission line source, the planetary nebula (PN) nature of the source Kn 26 has only recently been recognized in digital sky surveys. To investigate the spectral properties and spatio-kinematical structure of Kn 26, we have obtained high spatial-resolution optical and near-IR narrow-band images, high-dispersion long-slit echelle spectra, and intermediate-resolution spectroscopic observations. The new data reveal an hourglass morphology typical of bipolar PNe. A detailed analysis of its morphology and kinematics discloses the presence of a second pair of bipolar lobes, making Kn 26 a new member of the subclass of quadrupolar PNe. The time lapse between the ejection of the two pairs of bipolar lobes is much shorter than their dynamical ages, implying a rapid change in the preferential direction of the central engine. The chemical composition of Kn 26 is particularly unusual among PNe, with a low N/O ratio (as for type II PNe) and a high helium abundance (as for type I PNe), although not atypical among symbiotic stars. Such an anomalous chemical composition may have resulted from the curtailment of the time in the asymptotic giant branch by the evolution of the progenitor star through a common envelope phase. Based on observations made with the Nordic Optical Telescope (NOT) and the William Herschel Telescope (WHT) on the island of La Palma in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias (IAC), the 2.1-m telescope of the Observatorio Astronómico Nacional at the Sierra de San Pedro Mártir (OAN-SPM), and the 1.5-m telescope at the Observatorio de Sierra Nevada (OSN), Granada, Spain. NOT is operated jointly by Denmark, Finland, Iceland, Norway, and Sweden. WHT is operated by the Isaac Newton Group. The 2.1-m telescope at the OAN-SPM is a national facility operated by the Instituto de Astronomía of the Universidad Nacional Autónoma de México. The 1.5-m telescope at the OSN is operated by the

  18. Teaching of Astronomy: Scenarios of Teaching Practice in Elementary Schools. (Spanish Title: Enseñanza de la Astronomía: Semblanzas de la Práctica Docente en Educación Primaria.) Ensino de Astronomia: Cenários da Prática Docente no Ensino Fundamental

    Science.gov (United States)

    Marchi Gonzatti, Sônia Elisa; Spessatto De Maman, Andréia; Fernandes Borragini, Eliana; Kerber, Júlia Cristina; Haetinger, Werner

    2013-12-01

    atomización de los asuntos, aunque temas como movimientos de la Tierra y fenómenos astronómicos hayan sido citados por la mayoría de los participantes. En cuanto a las estrategias, se verifico que se emplean principalmente clases con el apoyo de recursos bidimensionales, como películas, textos, mapas y búsqueda en internet. Las principales dificultades fueron la falta de formación específica con respecto a los contenidos de Astronomía, y el nivel de abstracción exigido por los contenidos. De modo general, esos indicadores convergen para los resultados ya encontrados en otros estudios, en el que las deficiencias de la formación inicial de los profesores, o incluso su ausencia, dificulta el adecuado abordaje de la Astronomía en las clases. Neste trabalho são apresentados os principais resultados de uma investigação realizada no campo da Educação em Astronomia, com professores do ensino fundamental de duas regiões do Rio Grande do Sul. O objetivo do estudo foi caracterizar o cenário regional do ensino de Astronomia, estabelecendo um comparativo com o cenário nacional. Esse estudo abordou três questões: identificar os principais temas de astronomia trabalhados em sala de aula, as estratégias metodológicas e quais as dificuldades apresentadas pelos professores ao desenvolver sua prática. Quanto aos conteúdos, encontrouse uma pulverização dos assuntos abordados, embora temas como movimentos da Terra e fenômenos astronômicos tenham sido citados pela maioria dos participantes. Sobre estratégias, são utilizadas principalmente aulas com apoio de recursos bidimensionais, como filmes, textos, mapas e pesquisa na internet. As principais dificuldades foram: falta de formação específica em relação a conteúdos de Astronomia; nível de abstração dos conteúdos, que dificultam sua compreensão, tanto pelos alunos quanto pelos próprios professores. De maneira geral, esses indicadores convergem para resultados já encontrados em outros estudos que

  19. Difficulties of First Years Elementary School Teachers with the Teaching of Astronomy. (Breton Title: Dificuldades de Professores dos Anos Iniciais do Ensino Fundamental em Relação ao Ensino da Astronomia. ) Dificultades de LOS Profesores de los Primeros Años de la Escuela Primaria en Relación a la Enseñanza de la Astronomía

    Science.gov (United States)

    Langhi, Rodolfo; Nardi, Roberto

    2005-12-01

    This paper reports Primary School teachers' discourses analysis about their difficulties related to the teaching of Astronomy. It reports partial data of a master's level research carried out in the last two years, named "An exploratory study for inserting Astronomy in primary school teachers' education" (LANGHI, 2004). The study took into consideration students' and teachers' common sense conceptions about astronomical phenomena, conceptual mistakes in textbooks, and Astronomy's suggestions given by the PCN (Parâmetros Curriculares Nacionais - The Brazilian National Curriculum Standards). The paper aims to characterize teachers' difficulties, in order to provide subsides to the implementation of an initial or continuing education program. This study is justified by the fact that courses plans like these only will be adapted to the teacher's (and students') reality, if there is a primary investigation about what the teachers really need to know about Astronomy. This fact was possible here by the enunciations interpretation of a teachers' sample using semi-structured interviews, according to discourse analysis procedures. The research outcomes show difficulties related to factors like: those of personal order, methodological, on teacher's formation, educational infrastructure and other related to information sources for educators. Este artigo, que relata as dificuldades de professores em relação ao ensino da Astronomia, faz parte de um estudo exploratório para a inserção da Astronomia na formação de professores dos anos iniciais do Ensino Fundamental. Esse estudo leva em consideração as concepções alternativas de alunos e professores sobre fenômenos astronômicos, os erros conceituais em livros didáticos e as sugestões de conteúdos de Astronomia constantes nos PCN (Parâmetros Curriculares Nacionais). Caracterizar as dificuldades dos professores é a questão central deste texto, apontando para o objetivo de contribuir com subsídios para um futuro

  20. Radio Telescopes "Save the Day," Produce Data on Titan's Winds

    Science.gov (United States)

    2005-02-01

    eventually provide a three-dimensional record of motion for the Huygens Probe during its mission at Titan. Huygens was built by the European Space Agency. The radio astronomy support of the Huygens mission is coordinated by JIVE and JPL and involves the National Radio Astronomy Observatory (Green Bank, WV and Socorro, NM), the Netherlands Foundation for Research in Astronomy (ASTRON, The Netherlands), the University of Bonn (Germany), Helsinki University of Technology (Espoo, Finland), the MERLIN National Facility (Jodrell Bank, UK), the Onsala Space Observatory (Sweden), the NASA Jet Propulsion Laboratory (Pasadena, CA), the CSIRO Australia Telescope National Facility (ATNF, Sydney, Australia), the University of Tasmania (Hobart, Australia), the National Astronomical Observatories of China, the Shanghai Astronomical Observatory (Shanghai and Urumqi, China) and the National Institute of Information and Communications Technologies (Kashima Space Research Center, Japan). The Joint Institute for VLBI in Europe is hosted by ASTRON and funded by the national research councils, national facilities and institutes of The Netherlands (NOW), the United Kingdom (PPARC), Italy (CNR), Sweden (Onsala Space Observatory, National Facility), Spain (IGN) and Germany (MPIfR). The Australia Telescope is funded by the Commonwealth of Australia for operation as a National Facility managed by CSIRO. The Cassini-Huygens mission is a cooperation between NASA, ESA and ASI, the Italian space agency. The Jet Propulsion Laboratory (JPL), a division of the California Institute of Technology in Pasadena, is managing the mission for NASA's Office of Space Science, Washington DC. JPL designed, developed and assembled the Cassini orbiter while ESA operated the Huygens atmospheric probe. The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

  1. Disciplines and Professors of Astronomy in Undergraduate Physics Teachers Formation Courses in Brazilian Universities. (Spanish Title: Disciplinas y Profesores de Astronomia en los Cursos de Licenciatura en Física en Las Universidades Brasileñas.) Disciplinas e Professores de Astronomia Nos Cursos de Licenciatura em Física das Universidades Brasileiras

    Science.gov (United States)

    Roberto, Artur Justiniano, Jr.; Reis, Thiago Henrique; dos Reis Germinaro, Daniel

    2014-12-01

    This article is the result of a research on basic training in Astronomy in physics degrees that performed the ENADE 2011 national examination. The objective was to identify whether there are disciplines of Astronomy in these courses, whether are mandatory or optional, its workload and when it is offered. The relationship between astronomers, physics degrees and disciplines of Astronomy was investigated. To perform this research we examined the results of ENADE 2011 and also the census of Brazilian Astronomical Society. As a result it is observed that in only 15% of the courses there is a mandatory subject of Astronomy, and therefore there is a high probability that 85% of physics teachers trained in 2011 have not had any discipline of Astronomy during their graduation. In addition, the data collected in this study shows a low number of members of SAB (Sociedade Astronômica Brasileira) among the surveyed courses. We have verified that the presence of astronomers in a given university does not imply to have a mandatory discipline of Astronomy in physics degrees at the same university. Este artículo es el resultado de una investigación sobre la formación básica en Astronomía en los cursos de Profesorado en Física que hicieron el examen nacional ENADE 2011. El objetivo del trabajo fue identificar se existen disciplinas de Astronomía en estos cursos, si son obligatorias u optativas, cuál es su carga horaria y el semestre en que son ofrecidas. Se investigó también la correlación entre astrónomos, los cursos de licenciatura en Física y las disciplinas de Astronomía. Para realizar esta investigación se utilizaron los datos del ENADE 2011 y también del censo de la Astronomía brasileña. Como resultado, se observó que en solo 15% de los cursos existe una disciplina obligatoria de Astronomía y que existe una grande probabilidad de que 85% de los profesores de Física formados en el año de 2011 no hayan cursado ninguna disciplina de Astronomía durante su

  2. Development of Educational Resources to Include the Teaching of Astronomy in the First Years of the Basic Education. (Spanish Title: Desarrollo de Recursos Pedagógicos Para Incluir la Enseñanza de la Astronomía en los Primeros Años de la Educación Básica.) Desenvolvimento de Recursos Pedagógicos Para Inserir o Ensino de Astronomia nas Séries Iniciais do Ensino Fundamental

    Science.gov (United States)

    da Silva Morett, Samara; de Oliveira Souza, Marcelo

    2010-07-01

    ía y la vida cotidiana de los estudiantes. La inclusión de la astronomía en la escuela primaria es una manera de demostrar a los estudiantes cómo este campo está presente de forma activa en su vida cotidiana. Las clases que participan en el proyecto participaron en un estudio con el objetivo de proporcionar información a los conocimientos previos que tenían sobre los temas de la astronomía que se examinaron durante el proyecto. Con los experimentos realizados, y la ayuda de las nuevas tecnologías, conceptos astronómicos fueron presentados a los estudiantes de 4to y 5to año de la educación básica de una escuela municipal de Campos dos Goytacazes (RJ). Después de las presentaciones nuevos datos fueran colectados y se han llevado a cabo con el fin de verificar el nivel de aprendizaje alcanzado y se observó que el método utilizado fue una herramienta importante para ayudar al proceso de enseñanza y aprendizaje. El proyecto logró resultados satisfactorios. Neste trabalho será apresentado o desenvolvimento de recursos pedagógicos para a apresentação de conceitos de astronomia nas séries iniciais do ensino fundamental. Este material é composto por apresentações realizadas com o uso de novos recursos tecnológicos, pela fabricação de experimentos e a discussão de curiosidades relativas a esta área de conhecimento. Os experimentos foram construídos com material de baixo custo com o objetivo de permitir que os alunos envolvidos pudessem refazê-los em outras ocasiões. O material apresentado busca enfatizar a relação entre a astronomia e o cotidiano dos alunos. A inclusão da astronomia no ensino fundamental e uma forma de demonstrar aoestudante como esta área está presente de forma ativa em seu cotidiano. As turmas envolvidas no projeto participaram de uma pesquisa com o objetivo de obter dados relativos ao conhecimento prévio que possuíam sobre os tópicos de astronomia que foram considerados no decorrer do projeto. Com os experimentos

  3. The Understanding of Astronomy Concepts by Students from Basic Education of a Public School. (Spanish Title: El Entendimiento de Conceptos de Aastronmía Por Los Alumnos de Educación Básica en Una Escuela Pública.) O Entendimento de Conceitos de Astronomia Por Alunos da Educação Básica: O Caso de Uma Escola Pública Brasileira

    Science.gov (United States)

    Iria Machado, Daniel; dos Santos, Carlos

    2011-07-01

    We present the results obtained in a research on the comprehension of basic astronomical concepts, in which 561 students from fifth grade middle school to third grade high school of a public school of the city of Foz do Iguaçu (Brazil) took part. A test with 20 multiple-choice questions was applied to indentify the most common conceptions expressed by the students. This test was elaborated based on the literature about misconceptions and covered the following topics: the day-night cycle; the time zones; the seasons of the year; the phases of the Moon; the movement of the Moon; the apparent movement of the Sun in the celestial sphere; the eclipses; the dimensions and distances in the Universe; the brightness of the stars and its observation from Earth. Though a small progress was verified in the proportion of scientifically acceptable answers when comparing the eighth grade of middle school to the fifth, and the third grade of high school to the first, there was an overall predominance of alternative conceptions regarding most of the explored subjects, which persisted up to the last year of secondary school. The comparison to data found in this research made in other socio-cultural contexts revealed, in many aspects, similar notions and difficulties revealed by the students. Se presentan los resultados de una investigación sobre la comprensión de conceptos astronómicos básicos, en la cual participaron 561 estudiantes que cursaban entre el quinto grado de la enseñanza primaria y el tercer año de la enseñanza secundaria de una escuela pública de la ciudad de Foz do Iguaçu (Brasil). Se utilizó un test de 20 preguntas de opción múltiple para identificar las concepciones más comunes expresadas por los estudiantes. Este instrumento de recolección de datos se desarrolló en base a la literatura sobre las concepciones alternativas y trató los siguientes temas: el ciclo día-noche, los husos horarios, las estaciones del año, las fases de la Luna, el

  4. Development of Educational Resources to Include the Teaching of Astronomy in the First Years of the Basic Education. (Spanish Title: Desarrollo de Recursos Pedagógicos Para Incluir la Enseñanza de la Astronomía en los Primeros Años de la Educación Básica.) Desenvolvimento de Recursos Pedagógicos Para Inserir o Ensino de Astronomia nas Séries Iniciais do Ensino Fundamental

    Science.gov (United States)

    da Silva Morett, Samara; de Oliveira Souza, Marcelo

    2010-07-01

    ía y la vida cotidiana de los estudiantes. La inclusión de la astronomía en la escuela primaria es una manera de demostrar a los estudiantes cómo este campo está presente de forma activa en su vida cotidiana. Las clases que participan en el proyecto participaron en un estudio con el objetivo de proporcionar información a los conocimientos previos que tenían sobre los temas de la astronomía que se examinaron durante el proyecto. Con los experimentos realizados, y la ayuda de las nuevas tecnologías, conceptos astronómicos fueron presentados a los estudiantes de 4to y 5to año de la educación básica de una escuela municipal de Campos dos Goytacazes (RJ). Después de las presentaciones nuevos datos fueran colectados y se han llevado a cabo con el fin de verificar el nivel de aprendizaje alcanzado y se observó que el método utilizado fue una herramienta importante para ayudar al proceso de enseñanza y aprendizaje. El proyecto logró resultados satisfactorios. Neste trabalho será apresentado o desenvolvimento de recursos pedagógicos para a apresentação de conceitos de astronomia nas séries iniciais do ensino fundamental. Este material é composto por apresentações realizadas com o uso de novos recursos tecnológicos, pela fabricação de experimentos e a discussão de curiosidades relativas a esta área de conhecimento. Os experimentos foram construídos com material de baixo custo com o objetivo de permitir que os alunos envolvidos pudessem refazê-los em outras ocasiões. O material apresentado busca enfatizar a relação entre a astronomia e o cotidiano dos alunos. A inclusão da astronomia no ensino fundamental e uma forma de demonstrar aoestudante como esta área está presente de forma ativa em seu cotidiano. As turmas envolvidas no projeto participaram de uma pesquisa com o objetivo de obter dados relativos ao conhecimento prévio que possuíam sobre os tópicos de astronomia que foram considerados no decorrer do projeto. Com os experimentos

  5. The Shadow of a Gnomon Along a Year: Routine Observations and Teaching of Apparent Motion of the Sun and the Four Seasons. (Spanish Title: La Sombra de un Gnomon lo Largo de un Año: Observaciones de Rutina y la Enseñanza del Movimiento Aparente del Sol y Las Cuatro Estaciones.) A Sombra de um Gnômon ao Longo de um Ano: Observações Rotineiras e o Ensino do Movimento Aparente do Sol E das Quatro Estações

    Science.gov (United States)

    Trogello, Anderson Giovani; Danhoni Neves, Marcos Cesar; de Carvalho Rutz da Silva, Sani

    2013-12-01

    , al solsticio de junio, al equinoccio de septiembre y al solsticio de diciembre. Además, se dictaron clases teóricas en la sala de aula. Estos métodos buscaron construir conceptos en torno al movimiento aparente del Sol y la sucesión de las estaciones. Teniendo en cuenta los resultados de las actividades se aplicó una evaluación cuyos datos demuestran la existencia de un aprendizaje deseado por los estudiantes en cuanto a: el reconocimiento de los puntos cardinales, la descripción del movimiento solar aparente y la aparición de las estaciones y su alternancia a partir de observaciones astronómicas visuales sin instrumentos. Muitas concepções alternativas são reconhecidas entre os diversos grupos de estudantes, em especial nos da educação básica. Dentre elas, o movimento aparente do Sol, por mais quotidiano que seja, proporciona variadas interpretações. Deste modo, observar e registrar o movimento dos astros na abóboda celeste é uma tarefa necessária ao ensino de Astronomia. O trabalho que ora se apresenta propõe a apresentação dos resultados da observação do movimento aparente do Sol por intermédio da marcação da sombra de um gnômon vertical por alunos de uma turma do sexto ano do ensino fundamental de uma escola do campo do Paraná. O projeto em si ocorreu em quatro etapas, em datas próximas do equinócio de março, do solstício de junho, do equinócio de setembro e do solstício de dezembro. Além disso, foram desenvolvidas aulas teóricas em sala de aula. Tais métodos buscaram construir conceitos em torno da movimentação aparente do Sol e da alternância das estações do ano. Diante dos resultados provenientes das atividades desenvolvidas foi aplicada uma avaliação e os dados demonstraram um aprendizado desejado dos alunos quanto: ao reconhecimento dos pontos cardeais; à descrição do movimento solar aparente e a ocorrência das estações do ano e sua alternância a partir de observações astronômicas a olho nu.

  6. Enceladus' Interior: A Liquid Circulation Model

    Science.gov (United States)

    Matson, Dennis L.; Johnson, Torrence; Lunine, Jonathan; Castillo-Rogez, Julie

    transferred to the near-surface ice. The water is now relatively cold and dense. It absorbs the remaining bubbles and descends via fractures or defects in the ice, and percolates down to the "ocean". The water is in intimate contact with the ice and chemical interactions and heat exchange are possible. While the formation of the briny "ocean" was envisioned as due to the exclusion of non-water chemical species from the ice as it froze [8], a number of mechanisms permit a variety of organic and inorganic species to be present in the ice. The downward percolation of briny water facilitates these by making a large volume of the ice accessible along the crack surfaces. References: [1] J. H. Waite Jr et al., Nature, 460, 487-490 (2009). [2] F. Postberg et al., Nature, 459, 1098-1101 (2009). [3] S. W. Kieffer et al., Science, 314, 1764-1766 (2006). [4] C. Howett, J. R. Spencer, J. Pearl, M. Segura, Bull. Am. Astron. Soc., 41, 1122 (2009). [5] O. Abramov, J. R. Spencer, Icarus, 199, 189-196 (2009). [6] G. D. Crawford, D. J. Stevenson, Icarus, 73, 66-79 (1988). [7] S. L. Murchie, J. W. Head, LPS XVII, 583-584 (1986). [8] M. Y. Zolotov, Geophysical Research Letters, 34, L23203 (2007). This work has been conducted at the Jet Propulsion Laboratory, California Institute of Technology under a contract with the National Aeronautics and Space Administration, and for JIL under the program "Incentivazione alla mobilita' di studiosi straineri italiani residenti all'estero" of Italy.

  7. Mapping the complex kinematics of LL objects in the Orion nebula

    Science.gov (United States)

    Henney, William J.; García-Díaz, Ma. T.; O'Dell, C. R.; Rubin, Robert H.

    2013-01-01

    with density ≃3000 cm-3 (compared with a local nebula density of ≃1000 cm-3) and line ratios that are consistent with equilibrium photoionization models. The bowshock also has a fainter outer rim, where the line ratios show evidence of shock excitation. Many of the jet knots also show evidence for a shock contribution to their excitation and have densities from 1000 to 8000 cm-3. Based on observations obtained at the Observatorio Astronómico Nacional, San Pedro Mártir, Baja California, Mexico, which is operated by the Universidad Nacional Autónoma de México. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the National Science Foundation. iraf is distributed by the National Optical Astronomy Observatories, which is operated by the Association of Universities for Research in Astronomy, Inc., under cooperative agreement with the National Science foundation. Velocities in the frame of the local standard of rest are obtained by subtracting 18.1 km s-1 from the heliocentric values. Traditionally, [O iii] is normalized by Hβ rather than Hα in order to minimize the effects of extinction. In our case, the extinction is known to be low (Section 6), so the main effect of using Hα instead is to shift the y-axis by the intrinsic Balmer decrement of ˜0.5 dex.

  8. On the role of atomic metastability in the production of Balmer line radiation from ‘cold’ atomic hydrogen, deuterium and hydrogenic ion impurities in fusion edge plasmas

    Science.gov (United States)

    Hey, J. D.

    2012-03-01

    self-strength’ contributions, in accord with the sum rules for the line strengths, which remain valid over the range of fields considered. Thus, the relative effectiveness per perturber of both electron and ion collisions, for inducing population transfer between fine-structure sublevels, diminishes as the sublevels evolve from a fine-structure dominated to a Stark-effect-dominated regime. In the concluding discussion, we mention that this finding may have a bearing on discrepancies claimed between Stark broadening theory developed by Griem (1967 Astrophys. J. 148 547) and by Watson (2006 J. Phys.B: At. Mol. Opt. Phys. 39 1889), and the measurements of Bell and co-workers (2000 Publ. Astron. Soc. Pac. 112 1236; 2011 Astrophys. Space Sci. 335 451) for high-n radio recombination lines from galactic H II regions. In the absence of detailed modelling to test this suggestion, however, it would be premature to attempt to draw any firm conclusions along these lines. This manuscript is dedicated to the memory of my esteemed colleague Dr. rer. nat. Manfred Korten (1940-2010).

  9. A Milankovitch climate control on the Middle Miocene Mediterranean Intermediate Water: evidence from benthic microfauna and isotope geochemistry of the Ras Il-Pellegrin composite section (Malta island, central Mediterranean)

    Science.gov (United States)

    Rocca, D.; Bellanca, A.; Neri, R.; Russo, B.; Sgarrella, F.; Sprovieri, M.

    2003-04-01

    interpreted as a tracer of high production of proto-MIW, during periods of high eccentricity and, probably, precession minima, characterized by coldest winter seasons. These results point out a direct link between selected benthic species, long term astronomical forcing, and deep water response and provide an useful tool for astronomical calibration of geological time and paleoceanographic reconstructions. REFERENCES Johnson D. (1985). Abyssal teleconnections II. Initation of Antarctic Bottom Water flow in the southwestern Atlantic. In: Hsű K. And Weissert H. eds. - South Atlantic paleoceanography, 283-325, Cambridge (Cambridge University Press). Laskar J., Joutel F. &Boudin F. (1993). Orbital precession and insolation quantities for the Earth form 20 Myr to +10 Myr. Astron. Astrophys., 270: 522-533, Washinghon. Sprovieri M., Caruso A., Foresi L., Bellanca A., Neri R., Mazzola S. &Sprovieri R. (2002). Astronomical calibration of the upper Langhian/lower Serravallian record of Ras Il-Pellegrin section (Malta Island, central Mediterranean). In: Iaccarino S.M. (ed.) Integrated Stratigraphy and Paleoceanography of the Mediterranean Middle Miocene. Riv. It. Paleont. Strat., 108: 183-193, Milano. Woodruff F. &Savin S.M. (1991). Mid-Miocene isotope stratigraphy in the deep-sea: high resolution correlations, paleoclimatic cycles, and sediment preservation. Palaeoceanography, 6: 755-806, Washington.

  10. Analysis of astronomy knowledge of the students in the Federal Institute Sao Paulo

    Science.gov (United States)

    Moraes, A. C.; Voelzke, M. R.

    2014-08-01

    Este trabalho é parte integrante da pesquisa de mestrado acadêmico em ensino de ciências. Nele, busca-se apresentar os resultados da pesquisa realizada entre os 106 alunos do curso superior de tecnologia em automação industrial do Instituto Federal de Educação, Ciência e Tecnologia de São Paulo campus Cubatão, divididos em cinco turmas, duas no período matutino e três no período noturno. A análise dos resultados deste pré questionárioconstatou a falta de conhecimento básico dos discentes, sobre assuntos relacionados à astronomia, o que pode ser atribuído ao ineficiente processo de aprendizado pelo qual eles passaram tanto no ensino médio como no ensino fundamental, em escolas municipais, estaduais e particulares onde estudaram. No ensino de astronomia, têm-se diagnosticado constantemente diversas dificuldades conceituais tanto por parte de alunos como de professores de todas as áreas e níveis de ensino e poucos de fato a compreendem (ALBRECHT; VOELZKE, 2010). Demonstra-se as duas etapas concluídas do trabalho. A primeira etapa indica a análise dos conhecimentos prévios sobre conceitos astronômicos, através do questionário com 25 perguntas. A fim de corrigir as falhas constatadas, experimentalmente ministrou-se, externo ao conteúdo programático, um curso básico em astronomia, com diferentes estratégias de ensino, tais como, utilização de aulas expositivas dialogadas, recursos audiovisuais e palestras, para corrigir as dificuldades diagnosticadas. Essas estratégias de ensino se comprovaram adequadas às necessidades dos alunos e os conceitos foram finalmente compreendidos. Ao término do curso, completado o interstício de 120 dias, para caracterizar que houve a aprendizagem significativa, realizou-se uma nova pesquisa, quando, exatamente os mesmos 106 alunos responderam as mesmas 25 questões aplicadas na primeira etapa. Constata-se na segunda etapa, após análise, que em todas as questões, houve maior compreensão dos assuntos

  11. Comparison of Regression and Neural Networks Models to Estimate Solar Radiation Comparación de Regresión y Modelos de Redes Neuronales para Estimar la Radiación Solar

    Directory of Open Access Journals (Sweden)

    Mónica Bocco

    2010-09-01

    ón multicapa, para estimar la radiación solar global diaria y comparar la eficiencia de los mismos en su aplicación para una región de la Provincia de Salta, Argentina. Se utilizaron datos de heliofanía relativa, temperaturas máxima y mínima, precipitación, precipitación binaria y radiación solar astronómica provistos por la Estación Experimental Salta, Instituto Nacional de Tecnología Agropecuaria (INTA, Argentina, correspondientes al período 1996-2002. Tanto para los modelos de redes neuronales como para las regresiones lineales se consideraron tres alternativas de combinaciones de los parámetros meteorológicos, obteniéndose buenos resultados con ambas metodologías de predicción, con valores de la raíz del error cuadrático medio variando desde 1.99 a 1.66 MJ m-2 d-1 y coeficientes de correlación de 0.88 a 0.92. Se concluye que ambos, los modelos de redes neuronales y las regresiones lineales, pueden ser usados para predecir en forma adecuada la radiación solar global diaria; si bien las redes neuronales produjeron mejores resultados.

  12. Mal tiempo, tiempo maligno, tiempo de subversión ritual. La temposensitividad agrofestiva invernal

    Directory of Open Access Journals (Sweden)

    Del Campo Tejedor, Alberto

    2006-06-01

    Full Text Available In the light of a number of festive, ritual, poetico-musical and literary expresions, from Andalusia and elsewhere, the author discusses time as lived by agrarian cultures: a syncretic time, resulting from the superposition of civico-political, religious and peasant calendars; a cyclic time, given the effects of astronomico-meteorological time on nature and the subsequent cultural response on both the instrumental dimension (the work in the fields and the expresive dimension (the rituals and the festivals; and, finally, an ages-old bipolar time, experienced as the succession of two alternating seasons —wintertime and summertime—which also underlies a dichotomous agrofestive time-sensitiveness analyzed here under the following hypothesis: during the months of «good weather,» especially May and June, the rituals have a propitiatory and positively extolling sense; they mimetically dramatize the union between earth, vegetation, animals and humans by means of prototypes and archetypes that symbolically recreate the natural order of things. By contrast, the wintertime rituals and festivals—from 1st November till Carnival, and particularly around Christmas—all have in common a grotesque character and a sense of inverted order, symbolically signifying, with a logic at once serio-comic and ambiguous, the dark side of existence, while ritually conjuring up the fears of bad weather, of fateful and pernicious time, the time of cold nights, hunger and death.

    A la luz de algunas expresiones festivas, rituales, poético-musicales y literarias, de Andalucía y otros contextos, el artículo aborda el tiempo vivido por las culturas agroganaderas: un tiempo sincrético, como consecuencia de la superposición de los calendarios civil-político, religioso y campesino; un tiempo cíclico, fruto de la incidencia del tiempo astronómico-meteorológico en la naturaleza y la consiguiente respuesta cultural en el plano instrumental (los trabajos agr

  13. Direito à Educação no Brasil e dívida educacional: e se o povo cobrasse? Right to education in Brazil and the educational debt: what if the people actually demanded it?

    Directory of Open Access Journals (Sweden)

    Alceu Ravanello Ferraro

    2008-08-01

    Full Text Available Inicia-se tratando do direito à Educação no quadro dos direitos fundamentais da pessoa humana e do conceito de dívida educacional que decorre da não-realização do direito público subjetivo de cada cidadão e cidadã à Educação Fundamental completa, conforme estabelecido na Constituição de 1988. Utilizando como parâmetro a informação censitária sobre o número de anos de estudo concluídos com aprovação levantados no Censo 2000, estima-se que, nesse ano, o Estado brasileiro devia, aos 119,6 milhões de pessoas de 15 anos ou mais, a astronômica cifra de 325,5 milhões de anos de estudo não realizados na idade própria - uma média de quase três anos por pessoa. São projetados também os investimentos necessários em termos de professores e salas de aula/turno-ano para o resgate da dívida. Mostra-se ainda que a dívida estimada com base na Pesquisa Nacional por Amostra de Domicílios 2005 (316,4 milhões de anos de estudo devidos representa uma diminuição muito pequena em relação ao Censo 2000. Por fim, aborda-se a questão dos atores ou agentes da efetividade do direito à Educação e dos instrumentos de exigibilidade que a legislação põe à disposição desses mesmos agentes. Conclui-se afirmando que está posto aí, para a sociedade em geral e para educadores e educadoras em particular, o grande desafio de despertar nas pessoas humildes a consciência de que elas efetivamente têm direito à Educação e de que dispõem de meios para cobrar do Estado esse direito.We start by considering the right to Education within the framework of the fundamental human rights, and the ensuing concept of educational debt, which follows from the failure to enforce the subjective public right of each citizen to a complete Fundamental Education as established by the 1988 Brazilian Constitution. Based on the 2000 census information on the number of years of schooling successfully concluded, we estimate that in that year the Brazilian

  14. Nuclear planetology: understanding habitable planets as Galactic bulge stellar remnants (black dwarfs) in a Hertzsprung-Russell (HR) diagram

    Science.gov (United States)

    Roller, Goetz

    2016-04-01

    model constraining the evolution of a rocky planet like Earth or Mercury from a stellar precursor of the oldest population to a Fe-C BLD, shifting through different spectral classes in a HR diagram after massive decompression and tremendous energy losses. In the light of WD/BLD cosmochronology [1], solar system bodies like Earth, Mercury and Moon are regarded as captured interlopers from the Galactic bulge, Earth and Moon possibly representing remnants of an old binary system. Such a preliminary scenario is supported by similar ages obtained from WD's for the Galactic halo [1] and, independently, by means of 187Re-232Th-238U nuclear geochronometry [2, 4, 5], together with recent observations extremely metal-poor stars from the cosmic dawn in the bulge of the Milky Way [6]. This might be further elucidated in the near future by Th/U cosmochronometry based upon a nuclear production ratio Th/U = 0.96 [5] and additionally by means of a newly developed nucleogeochronometric age dating method for stellar spectroscopy, which will be presented in a forthcoming paper. The model shall stimulate geochemical data interpretation from a different perspective to constrain the (thermal) evolution of a habitable planet as to its geo-, bio-, hydro- and atmosphere. [1] Fontaine et al. (2001), Public. Astron. Soc. of the Pacific 113, 409-435. [2] Roller (2015), Abstract T34B-0407, AGU Spring Meeting 2015. [3] Arevalo et al. (2010), Chem. Geol. 271, 70-85. [4] Roller (2015), Geophys. Res. Abstr. 17, EGU2015-2399. [5] Roller (2015), 78th Annu. Meeting Met. Soc., Abstract #5041. [6] Howes et al. (2015), Nature 527, 484-487.

  15. Tidal torques: a critical review of some techniques

    Science.gov (United States)

    Efroimsky, Michael; Williams, James G.

    2009-07-01

    We review some techniques employed in the studies of torques due to bodily tides, and explain why the MacDonald formula for the tidal torque is valid only in the zeroth order of the eccentricity divided by the quality factor, while its time-average is valid in the first order. As a result, the formula cannot be used for analysis in higher orders of e/ Q. This necessitates some corrections in the current theory of tidal despinning and libration damping (though the qualitative conclusions of that theory may largely remain correct). We demonstrate that in the case when the inclinations are small and the phase lags of the tidal harmonics are proportional to the frequency, the Darwin-Kaula expansion is equivalent to a corrected version of the MacDonald method. The latter method rests on the assumption of existence of one total double bulge. The necessary correction to MacDonald’s approach would be to assert (following Singer, Geophys. J. R. Astron. Soc., 15: 205-226, 1968) that the phase lag of this integral bulge is not constant, but is proportional to the instantaneous synodal frequency (which is twice the difference between the evolution rates of the true anomaly and the sidereal angle). This equivalence of two descriptions becomes violated by a nonlinear dependence of the phase lag upon the tidal frequency. It remains unclear whether it is violated at higher inclinations. Another goal of our paper is to compare two derivations of a popular formula for the tidal despinning rate, and emphasise that both are strongly limited to the case of a vanishing inclination and a certain (sadly, unrealistic) law of frequency-dependence of the quality factor Q—the law that follows from the phase lag being proportional to frequency. One of the said derivations is based on the MacDonald torque, the other on the Darwin torque. Fortunately, the second approach is general enough to accommodate both a finite inclination and the actual rheology. We also address the rheological models

  16. The global shape, density and rotation of Comet 67P/Churyumov-Gerasimenko from preperihelion Rosetta/OSIRIS observations

    Science.gov (United States)

    Jorda, L.; Gaskell, R.; Capanna, C.; Hviid, S.; Lamy, P.; Ďurech, J.; Faury, G.; Groussin, O.; Gutiérrez, P.; Jackman, C.; Keihm, S. J.; Keller, H. U.; Knollenberg, J.; Kührt, E.; Marchi, S.; Mottola, S.; Palmer, E.; Schloerb, F. P.; Sierks, H.; Vincent, J.-B.; A'Hearn, M. F.; Barbieri, C.; Rodrigo, R.; Koschny, D.; Rickman, H.; Barucci, M. A.; Bertaux, J. L.; Bertini, I.; Cremonese, G.; Da Deppo, V.; Davidsson, B.; Debei, S.; De Cecco, M.; Fornasier, S.; Fulle, M.; Güttler, C.; Ip, W.-H.; Kramm, J. R.; Küppers, M.; Lara, L. M.; Lazzarin, M.; Lopez Moreno, J. J.; Marzari, F.; Naletto, G.; Oklay, N.; Thomas, N.; Tubiana, C.; Wenzel, K.-P.

    2016-10-01

    The Rosetta spacecraft reached Comet 67P/Churyumov-Gerasimenko (hereafter 67P/C-G) in August 2014 at an heliocentric distance of 3.6 a.u. and was then put in orbit around its nucleus to perform detailed observations. Among the collected data are the images acquired by the OSIRIS instrument up to the perihelion passage of the comet in August 2015, which allowed us to map the entire nucleus surface at high-resolution in the visible. Stereophotoclinometry methods have been used to reconstruct a global high-resolution shape model and to monitor its rotational parameters using data collected up to perihelion. The nucleus has a conspicuous bilobate shape with overall dimensions along its principal axes of (4.34 ± 0.02) × (2.60 ± 0.02) × (2.12 ± 0.06) km. The best-fit ellipsoid dimensions of the individual lobes along their principal axes of inertia are found to be 4.10 × 3.52 × 1.63 km and 2.50 × 2.14 × 1.64 km. Their volume amounts to 66% and 27% of the total volume of the nucleus. The two lobes are connected by a "neck" whose volume has been estimated to represent ∼7% of the total volume of the comet. Combining the derived volume of 18.8 ± 0.3 km3 with the mass of 9.982 ± 0.003 × 1012 kg determined by the Rosetta/RSI experiment, we obtained a bulk density of the nucleus of 532 ± 7 kg m-3 . Together with the companion value of 535 ± 35 kg m-3 deduced from the stereophotogrammetry shape model of the nucleus (Preusker et al. [2015] Astron. Astrophys. 583, A33), these constitute the first reliable and most accurate determination of the density of a cometary nucleus to date. The calculated porosity is quite large, ranging approximately from 70% to 75% depending upon the assumed density of the dust grains and the dust-to-ice mass ratio. The nature of the porosity, either micro or macro or both, remains unconstrained. The coordinates of the center of gravity are not compatible with a uniform nucleus density. The direction of the offset between the center of

  17. A Cocoon Found Inside the Black Widow's Web

    Science.gov (United States)

    2003-02-01

    NASA's Chandra X-ray Observatory image of the mysterious "Black Widow" pulsar reveals the first direct evidence of an elongated cocoon of high-energy particles. This discovery shows that this billion-year-old rejuvenated pulsar is an extremely efficient generator of a high-speed flow of matter and antimatter particles. Known officially as pulsar B1957+20, the Black Widow received its nickname because it is emitting intense high-energy radiation that is destroying its companion through evaporation. B1957+20, which completes one rotation every 1.6-thousandths of a second, belongs to a class of extremely rapidly rotating neutron stars called millisecond pulsars. The motion of B1957+20 through the galaxy -- at a high speed of almost a million kilometers per hour -- creates a bow shock wave visible to optical telescopes. The Chandra observation shows what cannot be seen in visible light: a second shock wave. This secondary shock wave is created from pressure that sweeps the wind back from the pulsar to form the cocoon of high-energy particles, visible for the first time in the Chandra data. "This is the first detection of a double-shock structure around a pulsar," said Benjamin Stappers, of the Dutch Organization for Research in Astronomy (ASTRON), lead author on a paper describing the research that will appear in the Feb. 28, 2003, issue of Science magazine. "It should enable astronomers to test theories of the dynamics of pulsar winds and their interaction with their environment." B1957+20 X-ray-only image of B1957+20 Scientists believe millisecond pulsars are very old neutron stars that have been spun up by accreting material from their companions. The steady push of the infalling matter on the neutron star spins it up in much the same way as pushing on a merry-go-round makes it rotate faster. The result is an object about 1.5 times as massive as the Sun and ten miles in diameter that rotates hundreds of times per second. The advanced age, very rapid rotation rate

  18. Does Titan's Slightly Oblate Shape suggest a Capture Origin?

    Science.gov (United States)

    Prentice, A. J.

    2010-12-01

    Cassini radar observations show that Titan is slightly oblate (Zebker et al, 2009 Science 324 921). The average polar radius falls short of the expected value by 120 m. The synchronously rotating ellipsoid of uniform density that best matches Titan’s shape has a spin rate that is 1.12 times faster than the present rate. Next, a freely-spinning, uniform-density, oblate spheroid of Titan’s mass and mean size which best fits the satellite’s shape has a polar radius which equals the observed value exactly. The spin rate of this hydrostatic equilibrium object is 1.97 times the present value. These calculation are based on the theory of rotating fluid satellites developed by Dermott (1988, Icarus 37 575). The Titan shape data, along with the existence of the non-zero value of the eccentricity of Titan’s orbit, re-awaken the possibility that Titan did not originally condense in orbit about Saturn (Prentice, 1980 JPL Publication 80-80; 1984 Earth, Moon and Planets 30 209). Instead, it is suggested that Titan first condensed as a secondary solid embryo within the gas ring that was shed by protosolar cloud (hereafter PSC) at Saturn’s orbital distance from the Sun. By forming in a free orbit about the PSC, Titan’s shape would have initially been that of an oblate spheroid, like Ceres. Next, the condensate that forms in the PSC gas ring of temperature 94 K consists of anhydrous rock (mass fraction 0.4925), water ice (0.4739) and graphite (0.0336). Its mean density at 94 K is 1.5221 g/cm3 (Prentice, 2006 Publ. Astron. Soc. Australia 23 1; 2007 38th LPSC, 2402.pdf). The gravity measurements of Iess et al (2010 Science 327 1367) have revealed that the interior of Titan is in a state of incomplete separation between the rock and ice phases. The axial moment of inertia is C/MR2 = 0.342. The gravity data suggest that the interior of Titan is cold and that its structure consists of a central core of rock and ice that is surmounted by a mantle of pure ice. The non

  19. Physical properties of interplanetary dust: laboratory and numerical simulations

    Science.gov (United States)

    Hadamcik, Edith; Lasue, Jeremie; Levasseur-Regourd, Anny-Chantal; Renard, Jean-Baptiste; Buch, Arnaud; Carrasco, Nathalie; Cottin, Hervé; Fray, Nicolas; Guan, Yuan Yong; Szopa, Cyril

    interplanetary dust organics approaching the Sun. Albedo and polarization variations will be discussed. The polarization evolution will be compared to those obtained through observations [11]. Studies of the properties of our interplanetary dust cloud should provide information to better interpret observations of dust around exoplanets. Some of these planets are very close to their star. The thermal evolution of organics driven by chemical reactions will represent a fundamental knowledge to interpret the relevant polarimetric observations. We acknowledge CNES for funding the PROGRA2 experiment, CNES and ESA for the micro-gravity flights. [1] Renard J.-B. et al., Appl. Opt. 41, 609 (2002) [2] Hadamcik E. et al., In: Light scattering rev. 4, 31 (Kokhanovszky ed.), Springer -Praxis, Berlin (2009) [3] Mann I. et al., Space Sci. Rev. 110, 269 (2004) [4] Hoertz F. et al., Science 314, 716 (2006) [5] Lasue J. et al., Astron. Astrophys. 473, 641 (2007) [6] Levasseur-Regourd A.C et al., Planet Space Sci. 55, 1010 (2007) [7] Hadamcik E. et al., Icarus 190, 660 (2007) [8] Cottin H. et al., Adv. Space Res. 42, 2019 (2008) [9] Fray N. et al., Planet. Space Sci. 53, 1243 (2005) [10] Sciamma-O'Brien E. et al., Icarus, accepted [11] Levasseur-Regourd A.C., et al., In: Interplanetary dust, Gruen, Gustafson B., Dermott S., Fechtig H. (Eds), Springer, Berlin, 57 (2001)

  20. The application of simple mass spectrometers to planetary sub-surface sampling using penetrators

    Science.gov (United States)

    Sheridan, Simon; Morse, Andrew; Bardwell, Max; Barber, Simeon; Wright, Ian

    2010-05-01

    (1-4), 363-387. Todd, J.F.J., Barber, S.J., Wright, I.P., Morgan, G.H., Morse, A.D., Sheridan, S., Leese, M.R., Maynard, J., Evans, S.T., Pillinger, C.T. et al. (2007). Ion trap mass spectrometry on a comet nucleus: the Ptolemy instrument and the Rosetta space mission. J. Mass Spectrom. 42,1-10. Pillinger C. T., and Wright I. P. (1993). MODULUS - Methods Of Determining and Understanding Light elements from Unequivocal Stable isotope composition. A type 2 proposal submitted to the RoLand Cometary Lander of the ESA International Rosetta Mission for the provision of Ptolemy - an evolved gas analyser. Richter L., Coste P., Grzesik A., Magnani P., Nadalini R., Neuhaus D., Re E., Romstedt J., Sims M. and Sohl F. (2005). Instrumented Moles for Planetary Subsurface Regolith Studies. Geophysical Research Abstracts, Vol. 7, 08659 A. Smith A.,. Crawford I. A., Gowen R. A., Ball A. J., Barber S. J., Church P., Coates A. J., Gao Y., Griffiths A. D., Hagermann A.,•Joy K. H., Phipps A., Pike W. T., Scott R., Sheridan S., Sweeting M., Talboys D.,•Tong V.,•Wells N.,• Biele J., Chela-Flores J.,•Dabrowski B., Flannagan J., Grande M., Grygorczuk J., Kargl G.,. Khavroshkin O. B.,•Klingelhoefer G., Knapmeyer M.,• Marczewski W., McKenna-Lawlor S.,•Richter L., Rothery D. A., Seweryn K., Ulamec S., Wawrzaszek R., Wieczorek M., Wright I. P. and Sims M. (2009). LunarEX - a proposal to cosmic vision. Exp Astron 23:711-740: DOI 10.1007/s10686-008-9109-6

  1. Two-Body Convection in the Mantle of the Earth: E/W Asymmetry, Under Astronomically Determined Tilt in g

    Science.gov (United States)

    Bostrom, R. C.

    2002-12-01

    Wegener to the present day [3], identifying a 'global tectonic polarity'; and westward drift, of which the asymmetry may be regarded as its engine. In sum, Earth's mantle is subject to three non-reversing force systems acting in the direction of causing net surface-west horizontal displacement, namely: I, Weak and tectonically insignificant forces ('tidal drag'), in unison constituting GH Darwin's tidal retarding couple; II, The forces inducing cumulative vorticity (TVI) [4] in an imperfectly elastic mantle, under passage of tidal M2. The operation of this system is ineluctable, and based on stress and energy consumption is likely to be significant, but its quantification requires separation of the marine from the bodily tidal energy dissipation utilizing secondary effects [4,5]; and III, Buoyancy-forces under convection now recognized as fundamental in geotectonics; - as normally modeled, greatly superadiabatic and dissipative, but within a field gconv minutely west-tilted, rather than artifically devoid of the Moon. Asymmetry of its internal gravity is unique to the asynchronous member of Kuiper's Earth-Moon double planet. The asymmetry distinguishes Earth's steady-state convection from the episodic regime of its moonless and almost non-rotating 'identical twin', Venus. Refs: [1] Tuoma, J. and J. Wisdom, 1994. Astron. J. 108(5) 1943-1961. [2] RCB, 2002. Episodes: J. Int. Geosc. 25(3), in pr. [3] Doglioni, C., 1993. J. Geol. Soc. 150, 991-1002. [4] RCB, 2000. Tectonic Consequences of Earth's Rotation (Oxford UP) s.4.3. [5] Lambeck, K., 1988. Geophysical Geodesy: The Slow Deformations of the Earth (Oxford UP) s. 11.3.

  2. The global surface composition of 67P/CG nucleus by Rosetta/VIRTIS. (I) Prelanding mission phase

    Science.gov (United States)

    Filacchione, Gianrico; Capaccioni, Fabrizio; Ciarniello, Mauro; Raponi, Andrea; Tosi, Federico; De Sanctis, Maria Cristina; Erard, Stéphane; Morvan, Dominique Bockelée; Leyrat, Cedric; Arnold, Gabriele; Schmitt, Bernard; Quirico, Eric; Piccioni, Giuseppe; Migliorini, Alessandra; Capria, Maria Teresa; Palomba, Ernesto; Cerroni, Priscilla; Longobardo, Andrea; Barucci, Antonella; Fornasier, Sonia; Carlson, Robert W.; Jaumann, Ralf; Stephan, Katrin; Moroz, Lyuba V.; Kappel, David; Rousseau, Batiste; Fonti, Sergio; Mancarella, Francesca; Despan, Daniela; Faure, Mathilde

    2016-08-01

    . The parallel coordinates method (Inselberg [1985] Vis. Comput., 1, 69-91) has been used to identify associations between average values of the spectral indicators and the properties of the geomorphological units as defined by (Thomas et al., [2015] Science, 347, 6220) and (El-Maarr et al., [2015] Astron. Astrophys., 583, A26). Three classes have been identified (smooth/active areas, dust covered areas and depressions), which can be clustered on the basis of the 3.2 μm organic material's band depth, while consolidated terrains show a high variability of the spectral properties resulting being distributed across all three classes. These results show how the spectral variability of the nucleus surface is more variegated than the morphological classes and that 67P/CG surface properties are dynamical, changing with the heliocentric distance and with activity processes.

  3. The Asteroid Identification Problem. II. Target Plane Confidence Boundaries

    Science.gov (United States)

    Milani, Andrea; Valsecchi, Giovanni B.

    1999-08-01

    important. We apply this technique to discuss the recent case of asteroid 1997 XF11, which, on the basis of the observations available up to March 11, 1998, appeared to be on an orbit with a near miss of the Earth in 2028. Although the least squares solution had a close approach at 1/8 of the lunar distance, the linear confidence regions corresponding to acceptable size of the residuals are very elongated ellipses which do not include collision; this computation was reported by Chodas and Yeomans. In this paper, we compute the semilinear confidence boundaries and find that they agree with the results of the Monte Carlo method, but differ in a significant way from the linear ellipses, although the differences occur only far from the Earth. The use of the 1990 prediscovery observations has confirmed the impossibility of an impact in 2028 and reduces the semilinear confidence regions to subsets of the regions computed with less data, as expected. The confidence regions computed using the linear approximation, on the other hand, do not reduce to subsets of the regions computed with less data. We also discuss a simulated example (Bowell and Muinonen 1992, Bull. Am. Astron. Soc.24, 965) of an Earth-impacting asteroid. In this hypothetical case the semilinear confidence boundary has a completely different shape from the linear ellipse, and indeed for orbits determined with only few weeks of observational data the semilinear confidence boundary correctly includes possible collisions, while the linear one does not. Free software is available now, allowing everyone to compute target plane confidence boundaries as in this paper; in case a new asteroid with worrisome close approaches is discovered, our method allows to quickly perform an accurate risk assessment.

  4. Análise Temporal da Coma de CO+ no Cometa P/Halley

    Science.gov (United States)

    Voelzke, M. R.; Schlosser, W.; Schmidt-Kaler, Th.

    1995-08-01

    Observações fotográficas e fotoelétricas da coma de gás ionizado do cometa P/Halley a nível de CO+ em 4250 angstroms fizeram parte do programa de Monitoramento do Halley desenvolvido pela Universidade de Bochum (Ruhr-Universitaet Bochum) na Alemanha, realizado de 17 de fevereiro a 17 de abril de 1986 no European Southern Observatory (ESO) em La Silla (Chile). Nesta faixa espectral é possível observar a contínua formação, bem como o movimento e expansão das estruturas de plasma. Para observar a morfologia destas estruturas foram analisadas 32 placas fotográficas de CO+ (placas de vidro) do cometa P/Halley. Tais placas possuem um campo de visão de 28,6 por 28,6 graus sendo obtidas entre 29 de março e 17 de abril de 1986 com tempos de exposição entre 20 e 120 minutos. Todas as placas foram digitadas com o auxílio de um microdensitômetro PDS 2020 GM (Photometric Data System) do Instituto Astronómico da Westfaelischen Wilhelms-Universitaet em Muenster, Alemanha (um pixel = 25 por 25 micrômetros correspondendo aproximadamente a 46,88 por 46,88 segundos de arco). Após a digitação os dados foram reduzidos à intensidades relativas, sendo que os posssíveis de calibração também foram reduzidos à intensidades absolutas, expressas em termos de densidade colunar utilizando-se dos sistemas de tratamento de imagens MIDAS (Munich Image Data Analysis System; ESO - Image Processing Group, 1988) e IHAP (Image Handling And Processing; Middleburg, 1983). Com o auxílio do método de teta mínimo de Stellingwerf (Stellingwerf, 1978) obteve-se um período de 2,22 +/- 0,09 dias a partir da análise de estruturas na coma de plasma através da subtração de imagens subsequentes. Este método foi comparado com o método de Fourier. Provavelmente exista um segundo ciclo com período aproximado de 3,6 dias. A idéia de subtrair imagens subsequentes é devido ao fato de que os efeitos de rotação são apenas 10% dos fenômenos de distribuição gasosa. Portanto as

  5. Emergence of Habitable Environments in Icy World Interiors

    Science.gov (United States)

    Neveu, Marc

    2016-07-01

    separation method that takes advantage of the density contrast between cells and sediment and preserves cellular elemental contents [11]. Using this method, I showed that in spite of the tremendous physical, chemical, and taxonomic diversity of Yellowstone hot springs, the composition of microorganisms there is surprisingly ordinary [12]. This suggests the existence of a stoichiometric envelope common to all life as we know it. Thus, future planetary investigations could use elemental fingerprints to assess the astrobiological potential of hydrothermal settings beyond Earth. References: [1] US National Research Council (2011)Vision & Voyages in the Decade 2013-2022. [2] Hussmann et al. (2006) Icarus 185, 258-273. [3] Desch et al. (2009) Icarus 202, 694-714. [4] Neveu et al. (2015) JGR 120, 123-154. [5] Neveu & Rhoden, in prep. [6] De Sanctis et al. (2015) Nature 528, 241-244. [7] Hsu et al. (2015) Nature 519, 207-210. [8] Wasson & Kallemeyn (1988) Phil Trans R Soc London A 325, 535-544. [9] Mumma & Charnley (2011) Annu Rev Astron Astrophys 49, 471. [10] Neveu et al., in revision. [11] Neveu et al. (2014) Limn Oceanogr 12, 519-529. [12] Neveu et al. (2016) Geobiology 14, 33-53.

  6. Nature and destruction of the Tunguska cosmical body

    Science.gov (United States)

    Bronshten, V. A.

    2000-08-01

    disintegration of large bodies in the atmosphere have been put forward by Grigoryan (1979: Motion and disintegration of meteorites in the planetary atmospheres. Cosmic Res. 17(6), 875-893), Hills and Goda (1993: The fragmentation of small asteroids in the atmosphere. Astron. J. 105(3) 1114-1144) (their theory is physically equivalent to Grigoryan's theory), and by Chyba et al. (1993: The Tunguska 1908 explosion: atmospheric disruption of a stony asteroid. Nature, 36 (1) 40-44.). The comparison of all the three theories is presented. It is shown that the theory of Chyba et al. overestimates the altitudes of disruption of the meteoroid compared to other theories. The results of the numerical simulations of the process in the free-Lagrangian and the Eulerian approximation (Svettsov V.V., Nemchinov I.V., Teterev A.V., 1995. Disintegration of large meteoroids in Earth's atmosphere: theoretical models. Icarus 116, 131-153) are also analysed. The results of numerous studies examined either do not contradict the cometary hypothesis of the TCB nature or the discrepancies (e.g. in the case of Chyba et al., 1993) can simply be explained. An interpretation is presented for the anomalous sky glow observed after the TCB fall, west of the treefall epicenter, in Russia and in West Europe. It was first put forward by the author ( Bronshten, 1991: Nature of the anomalous illumination of the sky related to the Tunguska event. Solar System Res. 25(4), 490-504) and considers the secondary scattering of solar light by the dust of the head of the comet that entered the Earth's atmosphere simultaneously with the TCB.

  7. Light scattering by clouds of cosmic dust analogues with carbonaceous compounds (PROGRA2 experiment)

    Science.gov (United States)

    Hadamcik, Edith; Renard, Jean-Baptiste; Levasseur-Regourd, Anny-Chantal; Lasue, Jeremie

    . The experiment is supported by CNES. The microgravity flights are operated by Novespace and funded by CNES and ESA. [1] H¨rz et al.,Science 314, 1716 (2006) [2] Sandford et al., Science 314, 1720 (2006) [3] Zolensky o et al., Science 314, 1736 (2006) [4] Kissel et al., Science 304, 1774 (2004) [5] Jessberger, Space Science Revue 90, 91 (1999) [6] Tomasko et al. Nature 438/8, 765 (2005) [7] Levasseur-Regourd and Hadamcik, JQSRT 79-80, 903 (2003) [8] Renard et al., App Opt 41, 609 (2002) [9] Hadamcik et al., Icarus 155, 497 (2002) [10] Hadamcik et al., JQSRT 100, 143 (2006) [11] Hadamcik and Levasseur-Regourd, Astron Astrophys 403, 757 (2003) [12] Hadamcik et al., Icarus 190, 459 (2007) [13] Hadamcik et al., Light Scattering Revue, vol 4 (accepted)

  8. The relationship between ENSO cycle and planetary positions ( Ⅰ): the apparent declination of Jupiter, Saturn and the equatorial eastern Pacific Ocean surface temperature%ENSO循环与行星位置的相互关系(Ⅰ):木星、土星视赤纬与赤道东太平洋海温的联系。

    Institute of Scientific and Technical Information of China (English)

    叶更新; 刘玉清

    2012-01-01

    The monthly Jupiter and Saturn apparent declinations has been calculated by using general astron- omy software SKYMap Pro Version 8, and comparitively studying the ENSO cycle and the key areas of equatorial Pacific sea surface temperature anomalies. The findings were that there was link between the two, namely, as the declination of Jupiter changes from positive through the equator to negative, EL - Nino event is likely to happen and the event duration is longer. Before 1980's this situation happened 3 times corresponding to the case of longer EL- Nino events. After 1980's at the two frequently- occurring stages of EL- Nino,the centers took place dur- ing the Jupiter declination conversion period from positive to negative. EL - Ninos often occur in the vicinity of the declination positive extreme value of Jupiter, and rarely in the negative values. LA - Nnia events tend to occur between the maximum and the equator of the Jupiter declination before 1980g,but after 1980g,it occurred in the vicinity of the negative extreme values of the Jupiter declination The position of Jupiter declination in some EL - Nino events is located in a nearly straight line. Over the past 60 years there have been four such lines. Therefore, the EL - Nino events can be divided into four groups, each group composed of 4 events accurately. When Saturn declination moves towards or away from the equator (in about ± 5°-10°) , EL -Nino occurs, but rarely occurs in the equatorial regions%利用通用天文软件SKYMapProVersion8计算了木星和土星的月视赤纬,将其与ENSO循环及赤道太平洋关键区海温距平进行对比分析,发现两者存在明显联系,主要包括:木星视赤纬由正经过赤道变为负时,容易发生EL-Nino事件,而且事件持续时间较长,1980年代及以前发生过3次这样的情况都对应持续较长的EL-Nino事件,1980年代以后的2次EL-Nino事件群发期,其中心都发生在木星视赤纬从正向负转

  9. Experimental Investigation of Nuclear Spin Conversion in Interstellar Pre-Cometary Ices

    Science.gov (United States)

    Broadhurst, C. L.; Mumma, M. J.

    1992-07-01

    conversion during formation and processing of thin mantles of water-based ices. Vapor is condensed in a specially designed cryogenic spectroscopy cell that has no paramagnetic surfaces. The cell is attached to the cold head of a closed-cycle He refrigerator, and the entire refrigerator shroud is placed inside an evacuable FTIR spectrometer. Ice samples are held at ~10 degrees K, and irradiated with VUV, thus simulating conditions in the intermediate density regions of interstellar clouds. The ice is then rapidly heated to the sublimation point; temperature during warm up and cool down is controllable to within 1 degree K. The resultant vapor is captured in the cell and the infrared spectrum collected with the FTS. First results from the experimental program will be presented. References: Eberhardt P. et al. (1987) Astron. Astrophys. 187, 481-184. Larson H.P. et al. (1989) Ap. J. 338, 1106-1114. Mumma et al. (1988) Proc. STScI Conference on Origins and Evolution of Planetary Systems. Zinner E. (1988) in Meteorites in the Early Solar System (eds. J.F. Kerridge and M.S. Matthews) pp. 956-983. Univ. Arizona Press, Tucson. AZ.

  10. On the universal stellar law

    Science.gov (United States)

    Krot, Alexander

    stars. In this connection, comparison with estimations of temperatures using of the regression dependences for multi-planet extrasolar systems [8] testifies the obtained results entirely. References 1. Krot, A.M.:2009, A statistical approach to investigate the formation of the solar system. Chaos, Solitons and Fractals41(3), 1481-1500. 2. Krot, A.M.:2012, A models of forming planets and distribution of planetary distances and orbits in the solar system based on the statistical theory of spheroidal bodies. In:Solar System: Structure, Formation and Exploration, ch.9 (Ed. by Matteo de Rossi). New York, Nova Science Publishers, pp. 201-264. - ISBN: 978-1-62100-057-0. 3. Krot, A. M.:2012, A statistical theory of formation of gravitating cosmogonicbodies. Minsk,Bel. Navuka, 4. 448 p. - ISBN 978-985-08-1442-5 [monograph in Russian]. 5. Eddington, A.S.: 1916,On the radiative equilibrium of the stars.Mon. Not. Roy. Astron. Soc.84 (7), 525-528. 6. Jeans, J.: 1929, Astronomy and cosmogony. Cambridge, University Press. 7. Chandrasekhar, S.:1939, An introduction to the study of stellar structure.Cambridge, University Press. 8. Pintr, P., Peřinová, V., Lukš, A., Pathak, A.:2013, Statistical and regression analyses of detected extrasolar systems. Planetary and Space Science, 75(1), 37-45.

  11. Radiation of molecules in Benešov bolide spectra

    Science.gov (United States)

    Borovička, J.; Berezhnoy, A. A.

    2016-11-01

    We analyzed molecular radiation in the spectra of the very bright Benešov bolide. The Benešov bolide appeared over the Czech Republic on May 7, 1991 and reached an absolute magnitude of -19.5. It was caused by a meteoroid larger than 1 m. Small meteorites of various mineralogical types were recovered recently (Spurný et al. [2014] Astron. Astrophys., 570, A39, 14 p.). The spectrum of the bolide, recorded on two photographic plates, is probably the richest meteor spectrum ever obtained. It contains hundreds of atomic emission lines, continuous radiation and molecular bands, and covers the whole bolide trajectory from the altitude of 90-20 km. In this paper we focus on identification and analysis of molecular bands. The identification of FeO, CaO, AlO, and MgO, reported earlier (Borovička and Spurný [1996] Icarus, 121, 484-510) was confirmed. In addition, radiation of N2 was probably detected. The oxides were best seen in the wake and in the radiating cloud left at the position of the bolide flare at the altitude of 24.5 km. Trace of N2 was seen only in the meteor at lower altitudes. FeO bands are present in the spectra from the highest altitudes. We suppose that FeO was ablated directly in molecular form at high altitudes. CaO was first detected just below 50 km and its intensity, relatively to FeO, strongly increased toward lower altitudes. AlO, which is similarly refractive as CaO, behaved as FeO rather than CaO at lower altitudes. MgO was observed only in the radiating cloud. The spectrum of the cloud is unique because it contains almost no atomic lines. We compared the data with theoretical calculations of the presence of molecules in the mixture of meteoric vapors and air at various altitudes and temperatures. CN and TiO were not found. The upper limit of CN is in agreement with theory for ordinary chondrite meteoroid. Most of carbon should be in fact present in the form of CO, but CO bands are too weak to be detected. The non-detection of TiO can be

  12. El urbanismo Inka y su vinculación con mesoclimas en el sitio "El Shincal de Quimivil" (Provincia de Catamarca, Argentina Inka urbanism associated with mesoclimatic conditions at the site "El Shincal de Quimivil" (Catamarca province, Argentina

    Directory of Open Access Journals (Sweden)

    Aylen Capparelli

    2006-12-01

    Full Text Available Los Inkas gestionaron el ambiente, de las distintas regiones que ocuparon, sobre la base tanto de sus conocimientos astronómicos -solares y lunares- como de aquellos referidos a la ecología y calendario agrícola -del maíz en especialde cada región. La producción excedente de una población se redistribuía luego en base a un sistema de almacenaje propio de este Estado. Dentro de este marco, se propone que el conocimiento de la diversidad de hábitats, y de los factores ecológicos a ellos asociados, les sirvió a los Inkas para planificar y garantizar el buen funcionamiento de cada unidad arquitectónica en cada centro administrativo. Por lo tanto, el objetivo principal de este trabajo es determinar si existe alguna vinculación entre las distintas condiciones mesoclimáticas que se encuentran en el lugar de implantación del sitio Inka El Shincal de Quimivil (Catamarca, Argentina y la distribución espacial de tres sectores arquitectónicofuncionales diferentes (almacenaje, habitacional, cultivo y un testigo (plaza. Se analizaron en forma univariada y multivariada 6 variables climáticas. Por sus altos valores de déficit de saturación de vapor del aire (DS, capacidad evaporante del aire y temperatura del suelo, el sector de almacenaje resultó el sector más propicio para lograr el secado y la preservación de los granos. El sector habitacional, mostró bajos DS y capacidad evaporante en primavera y verano, lo que contribuyó a condiciones más confortables bajo las elevadas temperaturas de esas estaciones. El sector cultivos, tuvo baja capacidad evaporante durante días con Zonda, y su mesoclima generalmente moderado, es el que más se ajusta a los requerimientos agroecológicos del maíz.The Inkas managed the environment of the different regions they occupied based on their astronomical and agroecological knowledge, especially in relation to maize. Surplus production was redistributed through a well developed storage system. Within

  13. Fundamental properties of nearby single early B-type stars

    Science.gov (United States)

    Nieva, María-Fernanda; Przybilla, Norbert

    2014-06-01

    and precision achieved in the determination of fundamental stellar parameters from the quantitative spectroscopy of single early B-type stars comes close (within a factor 2-4) to data derived from DEBs. While our fundamental parameters are in good agreement with those derived from DEBs as a function of spectral type, significant systematic differences with data from the astrophysical reference literature are found. Masses are ~10-20% and radii ~25% lower then the recommended values for luminosity class V, resulting in the stars being systematically fainter than assumed usually, by ~0.5 mag in absolute visual and bolometric magnitude. Our sample of giants is too small to derive firm conclusions, but similar trends as for the dwarfs are indicated. Based on observations collected at the Centro Astronómico Hispano Alemán (CAHA) at Calar Alto, operated jointly by the Max-Planck Institut für Astronomie and the Instituto de Astrofísica de Andalucía (CSIC), proposals H2001-2.2-011 and H2005-2.2-016. Based on observations collected at the European Southern Observatory, Chile, ESO 074.B-0455(A). Based on spectral data retrieved from the ELODIE archive at Observatoire de Haute-Provence (OHP). Based on observations made with the Nordic Optical Telescope, operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway, and Sweden, in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias.

  14. X-ray and optical observations of four polars

    Science.gov (United States)

    Worpel, H.; Schwope, A. D.; Granzer, T.; Reinsch, K.; Schwarz, R.; Traulsen, I.

    2016-08-01

    appear to be normal polars with luminosities and magnetic field strengths typical for this class of accreting binary. None of the four systems studied shows the strong soft excess thought commonplace in polars prior to the XMM-Newton era. Based on observations obtained with XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA Member States and NASA.Based on observations collected at the Centro Astronómico Hispano Alemán (CAHA) at Calar Alto, operated jointly by the Max Planck Institut für Astronomie and the Instituto de Astrofísica de Andalucía (CSIC).

  15. Single stars in the Hyades open cluster. Fiducial sequence for testing stellar and atmospheric models

    Science.gov (United States)

    Kopytova, Taisiya G.; Brandner, Wolfgang; Tognelli, Emanuele; Prada Moroni, Pier Giorgio; Da Rio, Nicola; Röser, Siegfried; Schilbach, Elena

    2016-01-01

    , photometry, and spectroscopy will greatly reduce the uncertainties in particular at the lowest mass range, and will enable us to test model predictions with greater confidence. Additionally, a small (~0.05 mag) systematic offset can be noted in J vs. J-K and K vs. H-K diagrams - the observed sequence is shifted to redder colors than the theoretical predictions. Based on observations collected at the Centro Astronómico Hispano Alemán (CAHA) at Calar Alto, operated jointly by the Max-Planck Institut für Astronomie and the Instituto de Astrofísica de Andalucía (CSIC).Full Table 2 is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/585/A7

  16. Mercury exosphere I. Global circulation model of its sodium component

    Science.gov (United States)

    Leblanc, Francois; Johnson, R. E.

    2010-10-01

    Our understanding of Mercury's sodium exosphere has improved considerably in the last 5 years thanks to new observations (Schleicher, H., Wiedemann, G., Wöhl, H., Berkefeld, T., Soltau, D. [2004]. Astron. Astrophys. 425, 1119-1124) and to the publication of a summary of the large set of ground based observations (Potter, A.E., Killen, R.M., Morgan, T.H. [2007]. Icarus 186, 571-580; Potter, A.E., Killen, R.M. [2008]. Icarus 194, 1-12; Potter et al., 2009). In particular, the non-uniformity in longitude of the dayside sodium distribution (the dawn/dusk asymmetry) has now been clearly observed. This suggests that Mercury's sodium exosphere is partly driven by a global day to nightside migration of the volatiles. One of the key questions remaining is the nature of the prevailing sodium ejection mechanisms. Because of the uncertain parameters for each ejection mechanisms, solving this problem has been difficult as indicated by the numerous papers over the last 15 years with very different conclusions. In addition, the variation of the size and of the spatial distribution of the surface reservoir (Leblanc, F., Johnson, R.E. [2003]. Icarus 164, 261-281) varies with distance from the Sun affecting the importance of each ejection mechanism on Mercury's orbital position. We here present an updated version of the Leblanc and Johnson (Leblanc, F., Johnson, R.E. [2003]. Icarus 164, 261-281) model. We take into account the two populations of sodium in the surface reservoir (Hunten, D.M., Morgan, T.M., Shemansky, D.M. [1988]. The Mercury atmosphere. In: Vilas, F., Chapman, C., Matthews, M. (Eds.), Mercury. University of Arizona Press, Tucson, pp. 562-612), one ambient population (physisorbed in the regolith with low binding energy) and one source population (chemisorbed coming from grain interior or from fresh dust brought to the surface and characterized by a higher binding energy). We also incorporate a better description of the solar wind sputtering variation with solar

  17. Impulsos climáticos da evolução na Amazônia durante o Cenozóico: sobre a teoria dos Refúgios da diferenciação biótica

    Directory of Open Access Journals (Sweden)

    J. Haffer

    2002-12-01

    Full Text Available AS FLUTUAÇÕES climático-vegetacionais causadas pelos ciclos astronômicos de Milan-kovitch provocaram mudanças globais na distribuição de florestas tropicais e demais vegetações não-florestais antes e durante o Cenozóico (Terciário-Quaternário. Os biomas continentais de florestas e vegetações não-florestais mudaram continuamente sua distribuição durante o seu passado geológico, fragmentando-se em blocos isolados, expandindo-se e juntando-se novamente sob condições climáticas alternadas entre secas e úmidas. Entretanto, durante as diversas fases climáticas, comunidades de plantas e animais fragmentaram-se e as espécies mudaram suas distribuições de maneira individual. Existem, para o Quaternário, dados de campo indicando mudanças na vegetação da Amazônia. A teoria dos Refúgios postula a persistência de grandes manchas de florestas tropicais úmidas durante os períodos secos do Terciário e do Quaternário, especialmente aquelas localizadas próximo de superfícies rebaixadas, sobretudo nas porções periféricas da Amazônia. Essas áreas são, provavelmente, a origem de muitas espécies e subespécies de plantas e animais existentes hoje em dia. Os "refúgios" úmidos podem ter sido separados por vários tipos de savana e florestas secas, como também por outros tipos de vegetação intermediária de climas sazonalmente secos. A quantidade e o tamanho dos refúgios durante os diferentes períodos de seca continuam desconhecidos. Indícios biogeográficos da existência de refúgios florestais anteriores incluem áreas de endemismo e zonas de contato entre espécies e subespécies de pássaros e outros animais da floresta amazônica nitidamente definidos. Essas áreas representam zonas de distinta descontinuidade biogeográfica num ambiente florestal contínuo. Modelos alternativos para a formação de barreiras na Amazônia que conduzem à especiação alopátrica incluem as seguintes hipóteses: do Rio, dos Ref

  18. The proximity of Mercury's spin to Cassini state 1 from adiabatic invariance

    Science.gov (United States)

    Peale, S. J.

    2006-04-01

    In determining Mercury's core structure from its rotational properties, the value of the normalized moment of inertia, C/MR, from the location of Cassini 1 is crucial. If Mercury's spin axis occupies Cassini state 1, its position defines the location of the state, where the axis is fixed in the frame precessing with the orbit. Although tidal and core-mantle dissipation drive the spin to the Cassini state with a time scale O(10) years, the spin might still be displaced from the Cassini state if the variations in the orbital elements induced by planetary perturbations, which change the position of the Cassini state, cause the spin to lag behind as it attempts to follow the state. After being brought to the state by dissipative processes, the spin axis is expected to follow the Cassini state for orbit variations with time scales long compared to the 1000 year precession period of the spin about the Cassini state because the solid angle swept out by the spin axis as it precesses is an adiabatic invariant. Short period variations in the orbital elements of small amplitude should cause displacements that are commensurate with the amplitudes of the short period terms. The exception would be if there are forcing terms in the perturbations that are nearly resonant with the 1000 year precession period. The precision of the radar and eventual spacecraft measurements of the position of Mercury's spin axis warrants a check on the likely proximity of the spin axis to the Cassini state. How confident should we be that the spin axis position defines the Cassini state sufficiently well for a precise determination of C/MR? By following simultaneously the spin position and the Cassini state position during long time scale orbital variations over past 3 million years [Quinn, T.R., Tremaine, S., Duncan, M., 1991. Astron. J. 101, 2287-2305] and short time scale variations for 20,000 years [JPL Ephemeris DE 408; Standish, E.M., private communication, 2005], we show that the spin axis

  19. Evolved stars and the origin of abundance trends in planet hosts

    Science.gov (United States)

    Maldonado, J.; Villaver, E.

    2016-04-01

    Galaxy. The sample of giants contains stars that are more massive and younger than their main-sequence counterparts. This leads to a sample of stars that are possibly less contaminated by stars that were not born in the solar neighbourhood, leading to no chemical differences between planet and non-planet hosts. The sample of main-sequence stars may contain more stars from the outer disc (specially the non-planet host sample) which might lead to the differences observed in the chemical trends. Based on observations made with the Mercator Telescope; on observations made with the Nordic Optical Telescope; on observations made with the Italian Telescopio Nazionale Galileo; on observations collected at the Centro Astronómico Hispano Alemán (CAHA) at Calar Alto; and on data products from observations made with ESO Telescopes at the La Silla Paranal Observatory under programme ID 072.C-0488(E), 080.D-0347(A), 081.D-0870(A), 087.C-0831(A), and 183.C-0972(A).Tables B.1-B.3 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/588/A98

  20. Vesta and low gravity impact mixing

    Science.gov (United States)

    Hoffmann, Martin; Nathues, Andreas; Vincent, Jean-Baptiste; Sierks, Holger

    2013-04-01

    impacts into granular material lead to anything but a simple crater morphology. Unusual scaling laws (Uehara et al. 2003) and much more diverse phase patterns than in ordinary solid media have to be taken into account, if a consistent interpretation of the formation of a crater in very deep regolith is attempted (e.g. Opsomer et al. 2011). Additional effects are due to the low gravity environment on a small planetary body like Vesta (Tancredi et al. 2012). On Vesta many apparent counterparts to the results of the experiments can be found, as demonstrated by some examples. On a global scale, the multitude of small, unresolved primary and secondary impacts into the granular regolith contributes to the observed maturity on Vesta even after short time scales. References Cook, M. A., Mortensen, K. S. 1967. Impact cratering in granular materials. J. Appl. Phys. 38, 5125-5128. Daniels, K. E., Coppock, J. E., Behringer, R. P. 2004. Dynamics of meteor impacts. Chaos 14, 84. Daraio, C., Nesterenko, V. F., Herbold, E. B., Jin S. 2006. Energy trapping and shock desintegration in a composite granular medium. Phys. Rev. Lett. 96, 058002, 1-4. Opsomer, E., Ludewig, F., Vandewalle, N. 2011. Phase transitions in vibrated granular systems in microgravity. Phys. Rev. E84, 051306, 1-5. Rivas, N., Ponce, S., Gellet, B., Risso, D., Soto, R., Cordero, P. 2011. Sudden chain energy transfer events in vibrated granular media. Phys. Rev. Lett. 106, 088001, 1-4. Tancredi, G., Maciel, A., Heredia, L., Richeri, P., Nesmachnow, S. 2012. Granular physics in low-gravity environments using discrete element method. Monthly Not. Royal Astron. Soc. 420, 3368-3380. Uehara, J. S., Ambroso, M. A., Ojha, R. J., Durian, D. J. 2003. Low-speed impact craters in loose granular media. Phys. Rev. Lett. 90, 194301, 1-4.

  1. Distant activity of Comet C/2002 VQ94 (LINEAR): Optical spectrophotometric monitoring between 8.4 and 16.8 au from the Sun

    Science.gov (United States)

    Korsun, Pavlo P.; Rousselot, Philippe; Kulyk, Irina V.; Afanasiev, Viktor L.; Ivanova, Oleksandra V.

    2014-04-01

    distance of 16.84 au, when the activity had probable ceased. The B-V and V-R colors were estimated to be 1.07 ± 0.05 and 0.54 ± 0.03 respectively. The effective nucleus radius of 48 ± 2 km is in agreement with the previously published results, obtained from the observations of the comet during its early inactive stage (Jewitt, D. [2005]. Astron. J. 129, 530-538; Weiler, M., Rauer, H., Sterken, C. [2011]. Icarus 212, 351-366).

  2. Nuevo algoritmo de detección y corrección de píxeles anómalos en imágenes A new algorithm for detecting and correcting bad pixels in infrared images

    Directory of Open Access Journals (Sweden)

    Restrepo Gir��n Andrés David

    2010-08-01

    Full Text Available Se expone un nuevo algoritmo de procesamiento de imágenes para detectar y corregir píxeles anómalos que resalten de manera individual entre sus vecinos en imágenes de una secuencia térmica obtenida a partir de un procedimiento de termografía activa, sin afectar la apariencia global de cada imagen, como ocurre al emplear una estrategia clásica de filtrado espacial. Como resultado principal de este filtrado selectivo, se detectan y reemplazan en un alto porcentaje aquellos píxeles defectuosos de fabricación o por el uso continuo del dispositivo CCD de la cámara infrarroja, lo cual re- duce el riesgo de malas interpretaciones en el análisis posterior. Para el desarrollo y prueba del algoritmo propuesto se utilizaron secuencias de video tomadas con una cámara Cincinnati Electronics de indio-antimonio (InSb para inspeccionar láminas de CFRP (plástico reforzado con fibra de carbono mediante la técnica de termografía activa. Los resultados del algoritmo se comparan con una lista de píxeles defectuosos dada por el fabricante de la cámara, arrojando un porcentaje de coincidencia de alrededor del 70%. El presente trabajo toma relevancia al considerar que en la literatura científica se encuentran muy pocos estudios en este campo, centrándose la mayoría en el preprocesamiento de imágenes astronómicas; además, en Colombia se está en una etapa de introducción creciente de técnicas de evaluación no destructiva por termografía (ENDT en amplios sectores industriales que incluyen generación y transmisión de energía, in- genios azucareros y aeronáutica militar, entre otros.An image processing algorithm detects and replaces abnormal pixels individually, highlighting them amongst their neighbours in a sequence of thermal images without affecting overall texture, like classical filtering does. Bad pixels from manufacture or constant use of a CCD device in an IR camera are thus detected and replaced with a very good success rate

  3. Astrodynamical Space Test of Relativity using Optical Devices I (ASTROD I)—a class-M fundamental physics mission proposal for cosmic vision 2015-2025: 2010 Update

    Science.gov (United States)

    Braxmaier, Claus; Dittus, Hansjörg; Foulon, Bernard; Göklü, Ertan; Grimani, Catia; Guo, Jian; Herrmann, Sven; Lämmerzahl, Claus; Ni, Wei-Tou; Peters, Achim; Rievers, Benny; Samain, Étienne; Selig, Hanns; Shaul, Diana; Svehla, Drazen; Touboul, Pierre; Wang, Gang; Wu, An-Ming; Zakharov, Alexander F.

    2012-10-01

    dedicated to probe gravitational waves at frequencies below the LISA bandwidth to 100 nHz and to detect solar g-mode oscillations. In the third phase (Super-ASTROD), larger orbits could be implemented to map the outer solar system and to probe primordial gravitational-waves at frequencies below the ASTROD bandwidth. This paper on ASTROD I is based on our 2010 proposal submitted for the ESA call for class-M mission proposals, and is a sequel and an update to our previous paper (Appouchaux et al., Exp Astron 23:491-527, 2009; designated as Paper I) which was based on our last proposal submitted for the 2007 ESA call. In this paper, we present our orbit selection with one Venus swing-by together with orbit simulation. In Paper I, our orbit choice is with two Venus swing-bys. The present choice takes shorter time (about 250 days) to reach the opposite side of the Sun. We also present a preliminary design of the optical bench, and elaborate on the solar physics goals with the radiation monitor payload. We discuss telescope size, trade-offs of drag-free sensitivities, thermal issues and present an outlook.

  4. Formation and growth of embryos of the Earth-Moon system

    Science.gov (United States)

    Ipatov, Sergei I.

    2016-07-01

    radius of a considered embryo), and at the growth of the mass of the Earth's embryo by 10 times, the mass of the Moon's embryo increased by a factor of 1.43 and 1.31 at the ratio k_d of the density of the growing Moon to that of the growing Earth equal to its present value (k_d=0.6) and for equal densities (k_d=1), respectively. For the case of small relative velocities of planetesimals, effective radii of the embryos are proportional to r^2, and at the growth of the Earth's embryo mass by 10 times, the Moon's embryo mass increased by a factor of 1.051 and 1.044 at k_d=0.6 and k_d=1, respectively. [1] Galimov E.M., Krivtsov A.M.: Origin of the Moon. New concept. / De Gruyter. Berlin. 2012. 168 p. [2] Ipatov S.I.: Mon. Not. R. Astron. Soc., 2010, vol. 403, pp. 405-414.

  5. Obituary -- Salvador González Bedolla

    Science.gov (United States)

    Peña, H. José

    1997-04-01

    It is with great sadness that I must communicate the passing of our colleague Salvador Félix González Bedolla. The observational astronomers of the Observatorio Astronómico Nacional owe much to his pioneering effort at San Pedro Mártir, work that formed him as an astronomer, and helped him become one of the best photometric observers in México and, at the Instituto de Astronomóa of the UNAM, the academic technician with the highest productivity of articles derived from observations at the OAN. Salvador was an excellent student. He obtained the highest achievement award (Gabino Barreda) in high school, studied physics at the Universidad Nacional Autónoma de México (UNAM) and also finished the credits for his Master's degree in Physics with only his thesis separating him from his degree, an act which was constantly put off until his death. He began his career in Astronomy in 1973 under Dr. Eugenio Mendoza. Later he worked with Josef Warman in the observation of short period stars in the Observatorio `José Arbol y Bonilla'' in Zacatecas, México. I then began working continuously with him in this field of research which, thanks to his great work capacity, produced very good results. He continued in these fields of research not only within the Institute of Astronomy, but also in other research facilities, especially two: With the variable group from the Observatory at Nice, France, beginning in 1985, specializing in the pulsation of early stars. His main interest was in the β Cep stars and in the possibility of relating these stars to the new types of variables (such as the OB stars, the `53 Per' variables, the `ultrashort' period and the ``slow'' and Be variables) discovered near this zone. Hence, in view of this, his efforts were aimed at monitoring the stars that belong to these new groups in order to discover if they are really different from the classical β Cep stars. Moreover, beginning in 1984, Salvador began working with a group of astronomers from

  6. Ionization structure and chemical abundances of the Wolf-Rayet nebula NGC 6888 with integral field spectroscopy

    Science.gov (United States)

    Fernández-Martín, A.; Martín-Gordón, D.; Vílchez, J. M.; Pérez Montero, E.; Riera, A.; Sánchez, S. F.

    2012-05-01

    slight underabundance in O/H; ii) an outer shell very intense in [OIII]λ5007 Å corresponding to the main sequence bubble broken up as a consequence of the collision between supergiant and WR shells. Nitrogen and oxygen do not appear enhanced here, but helium appears enriched; iii) and finally it includes an external and faint shell that surrounds the whole nebula like a thin skin representing the early interaction between the winds from the main sequence star with the ISM for which typical circumstellar abundances are derived. Based on observations collected at the Centro Astronómico Hispano Alemán (CAHA) at Calar Alto, operated jointly by the Max-Planck-Institut für Astronomie and the Instituto de Astrofísica de Andalucía (CSIC).Table 3 is available in electronic form at http://www.aanda.org

  7. Hemocompatibility of DLC coatings synthesized by ion beam assisted deposition

    Institute of Scientific and Technical Information of China (English)

    LI; Dejun

    2001-01-01

    [1]Gallagher, J. J., Simpson, J. A., Search for trapped electrons and a magnetic moment at Mars by Mariner IV, Science, 1965, 149: 1233—1239.[2]Russell, C. T., The magnetic field of Mars: Mars 3 evidence reexamined, Geophys. Res. Lett., 1978, 5: 81—86.[3]Riedler, W., Schwingenschun, K., Lichtenegger, H. et al., Interaction of solar wind with the planet Mars: Phobos 2 magnetic field observations, Planet. Space Sci., 1991, 39: 75—81.[4]Gringauz, K. I., What was known about the Martian magnetosphere before Phobos-2 mission, Planet. Space Sci., 1991, 39: 73—74.[5]Acuna, M. H., Connerney, J. E. P., Wasilewski, P. et al., Magnetic field and plasma observations at Mars: Initial results of the Mars global surveyor mission, Science, 1998, 279: 1676—1680.[6]Mohlmann, D., Riedler. W., Rustenbuch, J. et al., The question of an internal Martian magnetic field, Planet. Space Sci., 1991, 39: 83—88.[7]Shi, J. K., Liu, Z. X., Zhang, T. L., A theoretical study on the O+ ions of the Martian magnetosphere, Chin Astron Astrophys., 1999, 23: 377—383.[8]Rosenbauer, H., Shutte, N., Apathy, I. et al., Ions of Martian origin and plasma sheet in the Martian magnetotail: Initial results of TAUS experiment, Nature, 1989, 341: 612—614.[9]Lundin, R., Zakharov, A., Pelinen, R. et al., ASPERA/Phobos measurements of the ion outflow from the Martian ionosphere, Geophy. Res. Lett., 1990, 17: 873—876.[10]Verigin, M. I., Shutte, N. M., Galeev, A. A. et al., Ions of planetary origin in the Martian magnetosphere (Phobos 2 / TAUS experiment), Planet. Space Sci., 1991, 39: 131—137.[11]Lundin, R., Zakharov, A., Pelinen, R. et al., First measurements of the ionospheric plasma escape from Mars, Nature, 1989, 341: 609—612.[12]Lammer, H., Bauer, S. J., Nonthermal atmospheric escape from Mars and Titan, J. Geophys. Res., 1991, 96: 1819—1826.[13]Haider, S. A., O+ escape in the polar ion exosphere of Mars, Adv. Space Res., 1995, 16: 49

  8. Influence of tail-like magnetic field on O+ ion distribution in the Martian magnetosphere

    Institute of Scientific and Technical Information of China (English)

    SHI; Jiankui

    2001-01-01

    [1]Gallagher, J. J., Simpson, J. A., Search for trapped electrons and a magnetic moment at Mars by Mariner IV, Science, 1965, 149: 1233—1239.[2]Russell, C. T., The magnetic field of Mars: Mars 3 evidence reexamined, Geophys. Res. Lett., 1978, 5: 81—86.[3]Riedler, W., Schwingenschun, K., Lichtenegger, H. et al., Interaction of solar wind with the planet Mars: Phobos 2 magnetic field observations, Planet. Space Sci., 1991, 39: 75—81.[4]Gringauz, K. I., What was known about the Martian magnetosphere before Phobos-2 mission, Planet. Space Sci., 1991, 39: 73—74.[5]Acuna, M. H., Connerney, J. E. P., Wasilewski, P. et al., Magnetic field and plasma observations at Mars: Initial results of the Mars global surveyor mission, Science, 1998, 279: 1676—1680.[6]Mohlmann, D., Riedler. W., Rustenbuch, J. et al., The question of an internal Martian magnetic field, Planet. Space Sci., 1991, 39: 83—88.[7]Shi, J. K., Liu, Z. X., Zhang, T. L., A theoretical study on the O+ ions of the Martian magnetosphere, Chin Astron Astrophys., 1999, 23: 377—383.[8]Rosenbauer, H., Shutte, N., Apathy, I. et al., Ions of Martian origin and plasma sheet in the Martian magnetotail: Initial results of TAUS experiment, Nature, 1989, 341: 612—614.[9]Lundin, R., Zakharov, A., Pelinen, R. et al., ASPERA/Phobos measurements of the ion outflow from the Martian ionosphere, Geophy. Res. Lett., 1990, 17: 873—876.[10]Verigin, M. I., Shutte, N. M., Galeev, A. A. et al., Ions of planetary origin in the Martian magnetosphere (Phobos 2 / TAUS experiment), Planet. Space Sci., 1991, 39: 131—137.[11]Lundin, R., Zakharov, A., Pelinen, R. et al., First measurements of the ionospheric plasma escape from Mars, Nature, 1989, 341: 609—612.[12]Lammer, H., Bauer, S. J., Nonthermal atmospheric escape from Mars and Titan, J. Geophys. Res., 1991, 96: 1819—1826.[13]Haider, S. A., O+ escape in the polar ion exosphere of Mars, Adv. Space Res., 1995, 16: 49

  9. FRAM: SHOWERS, COMETS, GRBS AND POPULAR SCIENCE

    Directory of Open Access Journals (Sweden)

    J. Ebr

    2014-01-01

    Full Text Available E l t e l e s c o p i o F R A M , o p e r a d o p o r e l I n s t i t u t o d e F ́ ı s i c a d e l a A c a d e m i a d e C i e n c i a s d e l a R e p ́ u b l i c a C h e c a e s t ́ a u b i c a d o e n e l O b s e r v a t o r i o P i e r r e A u g e r d e A r g e n t i n a . S u o b j e t i v o p r i n c i p a l e s p r o v e e r c a l i b r a c i ́ o n a t m o s f ́ e r i c a a l m e d i r e l c o n t e n i d o d e a e r o s o l y l a s c a r a c t e r ́ ı s t i c a s d e l a a t m ́ o s f e r a s o b r e e l O b s e r v a t o r i o . Y a q u e e s t e p r o g r a m a t o m a s o l o u n a p e q u e ̃ n a p o r c i ́ o n d e l t i e m p o d e o b s e r v a c i ́ o n d i s p o n i b l e , e l t e l e s c o p i o t a m b i ́ e n h a c e s e g u i m i e n t o a una variedad de objetivos astron ́omicos, como GRBs, cometas, asteroides y estrellas variables. Dentro del p r o y e c t o G L O R I A h e m o s d e s a r r o l l a d o u n p r o g r a m a d e d i v u l g a c i ́ o n e x t e n s o , i n c l u y e n d o f r e c u e n t e s a p a r i c i o n e s d e n u e s t r o s r e s u l t a d o s e n l o s m e d i o s p a r a e l p ́ u b l i c o e n g e n e r a l.

  10. Resistance of 10 wheat varieties to Sitobion avenae at wheat seedling stage%10个小麦品种(材料)对麦长管蚜的室内苗期抗蚜性

    Institute of Scientific and Technical Information of China (English)

    胡想顺; 刘小凤; 胡祖庆; 张宇红; 赵惠燕; 张改生

    2011-01-01

    [目的]明确不同小麦品种对麦长管蚜(Sitobion avenae)的室内苗期抗性.[方法]在温室内采用每株小麦接种1头蚜虫的方法,测定了麦长管蚜在来源于3个国家的10个小麦品种上的发育历期(DD)、相对日均体重增长量(MRGR)和成虫日均产仔数(Rm),以此来确定不同小麦品种(材料)的抗蚜性.[结果]应用多元方差分析,多目标综合判别及聚类分析等方法分析表明,麦长管蚜在‘Ww2730’、‘98-10-30’、‘Astron’上的适应性最差,这几个品种对其抗性最好,是可以利用的抗性品种(材料);‘98-10-35’、‘98-10-32’次之;‘Batis’对麦长管蚜的适应性最好,抗性最差;‘186Tm’,‘Xanthus’,‘Amigo’对麦长管蚜适应性较好,与作为对照的‘小偃-22’一样,抗性处在中间水平.[结论]研究结果可以为进一步的抗蚜育种提供依据.%[Objective] To understand the resistance mechanism of different wheat varieties to Sitobion avenae at wheat seedling stage. [Method] Ten wheat varieties or hybrid progenies of the wheat Triticum sativum and einkorn Triticum monococcum L., or wheat and quack grass Agropyrum repens Beauvois from Germany, China and America were evaluated for their resistance to the cereal aphid S. Avenae in seedlings in glasshouses. Three biological parameters, including development days (DD), mean relative growth rate (MRGR) and rate of mean production (Rm), were used as the indicators for the level of plant resistance. [Result] Based on multivariate variance analysis, multi-objective integrated evaluation and cluster analysis, the results indicated that 'Ww2730', '98-10-30' and 'Astron' had the highest resistance to S. Avenae, followed by '98-10-35' and '98-10-32'. The first three varieties could be used as the resistant resources to S. Avenae in wheat breeding. 'Batis' had the lowest resistance. [Conclusion] The results may provide a basis for resistance breeding to aphids.

  11. First detection of Mars atmospheric hydroxyl: CRISM Near-IR measurement versus LMD GCM simulation of OH Meinel band emission in the Mars polar winter atmosphere

    Science.gov (United States)

    Todd Clancy, R.; Sandor, Brad J.; García-Muñoz, Antonio; Lefèvre, Franck; Smith, Michael D.; Wolff, Michael J.; Montmessin, Franck; Murchie, Scott L.; Nair, Hari

    2013-09-01

    Visible and near-IR Meinel band emissions originate from excited OH in the terrestrial upper atmosphere (Meinel, I.A.B. [1950]. Astrophys. J. 111, 555. http://dx.doi.org/10.1086/145296), and have recently been detected in the Venus nightside upper mesosphere (Piccioni, G. et al. [2008]. Astron. Astrophys. 483, L29-L33. http://dx.doi.org/10.1051/0004-6361:200809761). Meinel band observations support key studies of transport and photochemistry in both of these atmospheres. In the case of Mars, OH regulates the basic stability of the CO2 atmosphere to photolytic decomposition (to CO and O2, e.g. Parkinson, T.D., Hunten, D.M. [1972]. J. Atmos. Sci. 29, 1380-1390. http://dx.doi.org/10.1175/1520-0469(1972)0292.0.CO;2), and yet has never been measured. We present the first detection of Mars atmospheric OH, associated with CRISM near-IR spectral limb observations of polar night Meinel band emissions centered at 1.45 and 2.9 μm. Meinel band (1-0), (2-1), and (2-0) average limb intensities of 990 ± 280, 1060 ± 480, and 200 ± 100 kiloRayleighs (kR), respectively, are determined for 70-90 NS polar winter latitudes over altitudes of 40-56 km. Additional OH bands, such as (3-2), (3-1), and (4-2), present ⩽1σ measurements. Uncertainty in the (4-2) band emission rate contributes to increased uncertainty in the determination of the O2(1Δg) (0-0)/(0-1) band emission ratio A00/A01=47-12+26. An average profile retrieval for Mars OH polar nightglow indicates 45-55 km altitude levels for volume emission rates (VER) of 0.4 (2-0) to 2 (1-0, 2-1) × 104 photons/(cm3 s). Similar to polar night O2(1Δg) emission (e.g. Clancy, R.T. et al. [2012]. J. Geophys. Res. (Planets) 117, E00J10. http://dx.doi.org/10.1029/2011JE004018), Meinel OH band emission is supported by upper level, winter poleward transport of O and H in the deep Hadley solsticial circulations of Mars. The retrieved OH emission rates are compared to polar winter OH nightglow simulated by the LMD (Laboratoire de M

  12. Ritmitas mareales en la formación puncoviscana (S.L. en la localidad de Rancagua, Noroeste Argentino: Dinámica mareal y consideraciones paleoastronómicas Tidal rhythmites in the Puncoviscana Formation (s.l. at Rancagua locality, Northwestern Argentina: tidal dynamics and paleoastronomic considerations

    Directory of Open Access Journals (Sweden)

    Vanina L López de Azarevich

    2010-03-01

    Full Text Available Las ritmitas mareales constituyen una clara evidencia de sedimentación afectada por las mareas pudiendo preservar los períodos mareales inducidos astronómicamente al momento del depósito. Las investigaciones de secuencias periódicas mareales, acrecionadas vertical o lateralmente, en unidades modernas y antiguas, han experimentado notables avances en los últimos 25 años, excepto en la transición Neoproterozoico-eocámbrico. La Formación Puncoviscana (NO argentino está compuesta en la localidad de Rancagua por litofacies de cara de playa hasta plataforma distal, la cual incluye ritmitas mareales de edad neo-proterozoico- cámbrica temprana. Los períodos lunares involucrados en la sedimentación pueden ser aproximados mediante análisis armónicos con transformadas rápidas de Fourier a partir de datos crudos de espesores de láminas. Un sistema semidiurno con períodos tropicales de 26,64 días fue reconocido, a partir del cual se calculó la distancia Tierra-Luna en 3,78 x1010 cm. Estos resultados proporcionan información relevante acerca de la evolución de la órbita lunar a través del tiempo geológico. Los datos sugieren un evento astrofísico singular e irrepetible durante la transición Paleo-Mesoproterozoico con incremento en la velocidad de alejamiento hasta el Cámbrico Temprano, con eventos menores discretos en el Cámbrico Temprano y Paleozoico Superior con disminución del 50% de la velocidad de alejamiento.Tidal rhythmites are clear evidence of sedimentation affected by tides and could preserve tidal periods astronomically induced during the time of deposition. Investigations of tidal periodic sequences lateral or vertically accreted on modern and ancient units had improved notable advances during the last 25 years, but, there are no data on the Neoproterozoic-Early Cambrian transition. The Puncoviscana Formation (NW Argentina at Rancagua locality is composed by shoreface to offshore lithofacies, which includes tidal

  13. Simplificando a luneta com lente de óculos

    Science.gov (United States)

    Canalle, J. B. G.; de Souza, A. C. F.

    2003-08-01

    A principal ferramenta de trabalho do astrônomo é o telescópio. O manuseio do mesmo é sempre motivo de enorme curiosidade por parte de alunos do ensino fundamental ou médio e até mesmo dos respectivos professores. Visando propiciar o acesso de alunos e professores ou interessados em geral a uma luneta de fácil construção, com materiais alternativos, de fácil localização no comércio, de baixo custo, resistente ao manuseio de alunos, simplificamos a montagem de uma luneta construída com lente de óculos, de 1 ou 2 graus positivos, e monóculo de fotografia, publicado por este autor no CCEF, vol.11(3), 212, 1994. Esta luneta, a qual permite ver as crateras lunares, apresentava como maior dificuldade de construção o tripé e o local de formação da imagem. Substituímos o tripé de madeira por uma simples garrafa PET de 2 litros cheia d'água. No lugar da ocular usamos a lente do monóculo de fotografia (ou visor de fotografia) encaixado dentro de uma bucha de redução curta, de 40 x 32 mm, e esta não mais dentro de uma luva (conexão hidráulica) de 40 mm de diâmetro, mas sim encostada no próprio tubo de PVC móvel (o qual permite o ajuste do foco) de 40 mm de diâmetro e presa a este por outro tubo de 40 mm de diâmetro e 10 cm de comprimento, serrado ao longo do seu comprimento. Com isto podemos ajustar a posição deste tubo de 10 cm também para que uma das suas extremidades coincida com o local de formação da imagem. Desta forma o observador saberá o local exato da formação da imagem, o que não era evidente na montagem anterior e causava uma dificuldade inicial até se descobrir a posição exata em que se deveria colocar o olho. Deste maneira, a montagem inicial que já era simples ficou ainda mais simples, mais barata e mais confortável para o uso. Um exemplar da mesma será exposto durante a XXIX Reunião Anual da Sociedade Astronômica Brasileira para inspeção e uso dos participantes.

  14. Twenty-four-week effects of liraglutide on body composition, adherence to appetite, and lipid profile in overweight and obese patients with type 2 diabetes mellitus

    Directory of Open Access Journals (Sweden)

    Rondanelli M

    2016-03-01

    Full Text Available Mariangela Rondanelli,1 Simone Perna,1 Paolo Astrone,2 Annalisa Grugnetti,2 Sebastiano Bruno Solerte,2 Davide Guido3,4 1Endocrinology and Nutrition Unit, Section of Human Nutrition, Department of Public Health, Experimental and Forensic Medicine, Agency for Elderly People Services, Santa Margherita Hospital, University of Pavia, Pavia, Italy; 2Section of Geriatrics and Gerontology, Department of Internal Medicine, Agency for Elderly People Services, Santa Margherita Hospital, University of Pavia, Pavia, Italy; 3Medical and Genomics Statistics Unit, Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy; 4Biostatistics and Clinical Epidemiology Unit, Department of Public Health, Experimental and Forensic Medicine, University of Pavia, Pavia, Italy Background: Liraglutide has well-known effects on glucose patterns. However, its several other metabolic properties are still controversial. Given this background, the aims of the present study are to evaluate the effects of 24-week liraglutide treatment on body composition, appetite, and lipid profile in overweight and obese type 2 diabetes mellitus (T2DM patients. Methods: A cohort study was carried out on overweight and obese T2DM patients with glycosylated hemoglobin A1c equal to 6% (42 mmol/mol-10% (86 mmol/mol, under a 3-month treatment (at least with maximal dose of metformin as stable regime, by adding liraglutide at doses up to 3 mg/d. Body composition markers were measured by dual-energy X-ray densitometry at baseline and after 24 weeks of liraglutide treatment. Glucose control was monitored by glucose, glycosylated hemoglobin A1c, insulin, and homeostasis model assessment. Finally, the appetite sensation and plasma lipids were also evaluated. Results: Twenty-eight subjects (male/female: 16/12, mean age: 58.75±9.33 years, body mass index: 34.13±5.46 kg/m2 were evaluated. Accounting for the adjustment for age, sex, and duration of diabetes, we noted significant

  15. Temperature, gravity, and bolometric correction scales for non-supergiant OB stars

    Science.gov (United States)

    Nieva, M.-F.

    2013-02-01

    , and in extreme cases, + 6000 K and ± 0.4 dex, respectively. A parameter calibration for sub-spectral types is also proposed. Moreover, we present a new bolometric correction relation to temperature based on our empirical data, rather than on synthetic grids. Conclusions: The photometric calibrations presented here are useful tools to estimate effective temperatures and surface gravities of non-supergiant OB stars in a fast manner. This is also applicable to some single-line spectroscopic binaries, but caution has to be taken for undetected double-lined spectroscopic binaries and single objects with anomalous reddening-law, dubious photometric quantities and/or luminosity classes, for which the systematic uncertainties may increase significantly. We recommend to use these calibrations only as a first step of the parameter estimation, with subsequent refinements based on spectroscopy. A larger sample covering more uniformly the parameter space under consideration will allow refinements to the present calibrations. Based on observations collected at the Centro Astronómico Hispano Alemán (CAHA) at Calar Alto, operated jointly by the Max- Planck Institut für Astronomie and the Instituto de Astrofísica de Andalucía (CSIC), proposals H2001-2.2-011 and H2005-2.2-016.Based on observations collected at the European Southern Observatory, Chile, ESO 074.B-0455(A) and from the ESO Archive.Based on spectral data retrieved from the ELODIE archive at Observatoire de Haute-Provence (OHP).Appendices A and B are available in electronic form at http://www.aanda.org

  16. The non-interior continuation methods for solving the P0 function nonlinear complementarity problem

    Institute of Scientific and Technical Information of China (English)

    HUANG; Zhenghai

    2001-01-01

    [1]Kristian, J. , Sandage, A. R. , Westphal, J., The extension of the Hubble diagram: Ⅱ. New redshifts and photometry of very distant galaxy clusters, Astrophys. J., 1978, 221: 383.[2]Sandage, A., The redshift-distant relation V. Galaxy co lors as functions of galactic latitude and redshift, Astrophys, J.,1973, 183: 711.[3]Qu, Q. Y., Qin, Z. H., Han, C. S. et al., A relation between magnitudes and redshifts of QSOs with strong interplanetary scientillation, Chinese Astron., 1979, 4: 97.[4]Tinsley, B. M. , The Galaxy counts, color-redshift relation, and related quantities as probes of cosmology and galactic evolu-tion, Astrophys. J., 1977, 211: 621.[5]Spinrad, H., Djorgovski, S., The status of the Hubble diagram in 1986 (eds. Hewitt, A. Burbidge, G. Fang, L. Z. ),Proc. IAU Symp 124 on Observational Cosmology, New York: D. Reidel Publishing Company, 1986, 129.[6]Fang, L. Z., Zhou, Y. Y., Cheng F. Z. et al., Evolution of quasars with resolved components and determination of decel-eration parameter q0, Scientia Sinica, 1979, 22: 1292.[7]Cheng, K. S., Fan, J. H., Li, Y. et al., Do γ-ray burst associated with metal-rich quasars (ed. Cheng, K. S., Singh,H. P.), Proc. of The Pacific Rim Conference on Stellar Astrophysics, August 13-16, 1997, Houg Kong, 1997.[8]Davis, M., Geller, M. J., Huchra, J., The local mean mass density of the universe: new methods for studying galaxy clus-tering, Astrophys. J., 1978, 221: 1.[9]Gott, J. R., Turner, E. L., The mean luminosity and mass densities in the universe, Astrophys. J., 1976, 209: 1.[10]Shapiro, S. L., The density of matter in the form of galaxies, Astron. J., 1971, 76: 291.[11]Fang, L. Z., Hu, F. X., The large-scale inhomogeneities in the universe (eds. Yang, J., Zhu, C. S. ), Proceeding of A-cademia Sinica--Max-Plank Socity Workshop on High Energy Astrophyics Held in Nanjing, China, April 9-17, 1982,New York: Gordon and Breach Science Publishers S.A. 1982, 425[12]Baldwin, J. A

  17. Preparation and optical properties of GaSb nanoparticles embedded in SiO2 composite films

    Institute of Scientific and Technical Information of China (English)

    LIU; Famin

    2001-01-01

    [1]Kristian, J. , Sandage, A. R. , Westphal, J., The extension of the Hubble diagram: Ⅱ. New redshifts and photometry of very distant galaxy clusters, Astrophys. J., 1978, 221: 383.[2]Sandage, A., The redshift-distant relation V. Galaxy co lors as functions of galactic latitude and redshift, Astrophys, J.,1973, 183: 711.[3]Qu, Q. Y., Qin, Z. H., Han, C. S. et al., A relation between magnitudes and redshifts of QSOs with strong interplanetary scientillation, Chinese Astron., 1979, 4: 97.[4]Tinsley, B. M. , The Galaxy counts, color-redshift relation, and related quantities as probes of cosmology and galactic evolu-tion, Astrophys. J., 1977, 211: 621.[5]Spinrad, H., Djorgovski, S., The status of the Hubble diagram in 1986 (eds. Hewitt, A. Burbidge, G. Fang, L. Z. ),Proc. IAU Symp 124 on Observational Cosmology, New York: D. Reidel Publishing Company, 1986, 129.[6]Fang, L. Z., Zhou, Y. Y., Cheng F. Z. et al., Evolution of quasars with resolved components and determination of decel-eration parameter q0, Scientia Sinica, 1979, 22: 1292.[7]Cheng, K. S., Fan, J. H., Li, Y. et al., Do γ-ray burst associated with metal-rich quasars (ed. Cheng, K. S., Singh,H. P.), Proc. of The Pacific Rim Conference on Stellar Astrophysics, August 13-16, 1997, Houg Kong, 1997.[8]Davis, M., Geller, M. J., Huchra, J., The local mean mass density of the universe: new methods for studying galaxy clus-tering, Astrophys. J., 1978, 221: 1.[9]Gott, J. R., Turner, E. L., The mean luminosity and mass densities in the universe, Astrophys. J., 1976, 209: 1.[10]Shapiro, S. L., The density of matter in the form of galaxies, Astron. J., 1971, 76: 291.[11]Fang, L. Z., Hu, F. X., The large-scale inhomogeneities in the universe (eds. Yang, J., Zhu, C. S. ), Proceeding of A-cademia Sinica--Max-Plank Socity Workshop on High Energy Astrophyics Held in Nanjing, China, April 9-17, 1982,New York: Gordon and Breach Science Publishers S.A. 1982, 425[12]Baldwin, J. A

  18. The Hubble diagram of metal-rich QSOs and deceleration parameter q0

    Institute of Scientific and Technical Information of China (English)

    XIE; Guangzhong(

    2001-01-01

    [1]Kristian, J. , Sandage, A. R. , Westphal, J., The extension of the Hubble diagram: Ⅱ. New redshifts and photometry of very distant galaxy clusters, Astrophys. J., 1978, 221: 383.[2]Sandage, A., The redshift-distant relation V. Galaxy co lors as functions of galactic latitude and redshift, Astrophys, J.,1973, 183: 711.[3]Qu, Q. Y., Qin, Z. H., Han, C. S. et al., A relation between magnitudes and redshifts of QSOs with strong interplanetary scientillation, Chinese Astron., 1979, 4: 97.[4]Tinsley, B. M. , The Galaxy counts, color-redshift relation, and related quantities as probes of cosmology and galactic evolu-tion, Astrophys. J., 1977, 211: 621.[5]Spinrad, H., Djorgovski, S., The status of the Hubble diagram in 1986 (eds. Hewitt, A. Burbidge, G. Fang, L. Z. ),Proc. IAU Symp 124 on Observational Cosmology, New York: D. Reidel Publishing Company, 1986, 129.[6]Fang, L. Z., Zhou, Y. Y., Cheng F. Z. et al., Evolution of quasars with resolved components and determination of decel-eration parameter q0, Scientia Sinica, 1979, 22: 1292.[7]Cheng, K. S., Fan, J. H., Li, Y. et al., Do γ-ray burst associated with metal-rich quasars (ed. Cheng, K. S., Singh,H. P.), Proc. of The Pacific Rim Conference on Stellar Astrophysics, August 13-16, 1997, Houg Kong, 1997.[8]Davis, M., Geller, M. J., Huchra, J., The local mean mass density of the universe: new methods for studying galaxy clus-tering, Astrophys. J., 1978, 221: 1.[9]Gott, J. R., Turner, E. L., The mean luminosity and mass densities in the universe, Astrophys. J., 1976, 209: 1.[10]Shapiro, S. L., The density of matter in the form of galaxies, Astron. J., 1971, 76: 291.[11]Fang, L. Z., Hu, F. X., The large-scale inhomogeneities in the universe (eds. Yang, J., Zhu, C. S. ), Proceeding of A-cademia Sinica--Max-Plank Socity Workshop on High Energy Astrophyics Held in Nanjing, China, April 9-17, 1982,New York: Gordon and Breach Science Publishers S.A. 1982, 425[12]Baldwin, J. A

  19. Formation and construction of shock for psystem

    Institute of Scientific and Technical Information of China (English)

    CHEN; Shuxing

    2001-01-01

    [1]Kristian, J. , Sandage, A. R. , Westphal, J., The extension of the Hubble diagram: Ⅱ. New redshifts and photometry of very distant galaxy clusters, Astrophys. J., 1978, 221: 383.[2]Sandage, A., The redshift-distant relation V. Galaxy co lors as functions of galactic latitude and redshift, Astrophys, J.,1973, 183: 711.[3]Qu, Q. Y., Qin, Z. H., Han, C. S. et al., A relation between magnitudes and redshifts of QSOs with strong interplanetary scientillation, Chinese Astron., 1979, 4: 97.[4]Tinsley, B. M. , The Galaxy counts, color-redshift relation, and related quantities as probes of cosmology and galactic evolu-tion, Astrophys. J., 1977, 211: 621.[5]Spinrad, H., Djorgovski, S., The status of the Hubble diagram in 1986 (eds. Hewitt, A. Burbidge, G. Fang, L. Z. ),Proc. IAU Symp 124 on Observational Cosmology, New York: D. Reidel Publishing Company, 1986, 129.[6]Fang, L. Z., Zhou, Y. Y., Cheng F. Z. et al., Evolution of quasars with resolved components and determination of decel-eration parameter q0, Scientia Sinica, 1979, 22: 1292.[7]Cheng, K. S., Fan, J. H., Li, Y. et al., Do γ-ray burst associated with metal-rich quasars (ed. Cheng, K. S., Singh,H. P.), Proc. of The Pacific Rim Conference on Stellar Astrophysics, August 13-16, 1997, Houg Kong, 1997.[8]Davis, M., Geller, M. J., Huchra, J., The local mean mass density of the universe: new methods for studying galaxy clus-tering, Astrophys. J., 1978, 221: 1.[9]Gott, J. R., Turner, E. L., The mean luminosity and mass densities in the universe, Astrophys. J., 1976, 209: 1.[10]Shapiro, S. L., The density of matter in the form of galaxies, Astron. J., 1971, 76: 291.[11]Fang, L. Z., Hu, F. X., The large-scale inhomogeneities in the universe (eds. Yang, J., Zhu, C. S. ), Proceeding of A-cademia Sinica--Max-Plank Socity Workshop on High Energy Astrophyics Held in Nanjing, China, April 9-17, 1982,New York: Gordon and Breach Science Publishers S.A. 1982, 425[12]Baldwin, J. A

  20. A new kind of graded Lie algebra and parastatistical supersymmetry

    Institute of Scientific and Technical Information of China (English)

    YANG; Weimin

    2001-01-01

    [1]Kristian, J. , Sandage, A. R. , Westphal, J., The extension of the Hubble diagram: Ⅱ. New redshifts and photometry of very distant galaxy clusters, Astrophys. J., 1978, 221: 383.[2]Sandage, A., The redshift-distant relation V. Galaxy co lors as functions of galactic latitude and redshift, Astrophys, J.,1973, 183: 711.[3]Qu, Q. Y., Qin, Z. H., Han, C. S. et al., A relation between magnitudes and redshifts of QSOs with strong interplanetary scientillation, Chinese Astron., 1979, 4: 97.[4]Tinsley, B. M. , The Galaxy counts, color-redshift relation, and related quantities as probes of cosmology and galactic evolu-tion, Astrophys. J., 1977, 211: 621.[5]Spinrad, H., Djorgovski, S., The status of the Hubble diagram in 1986 (eds. Hewitt, A. Burbidge, G. Fang, L. Z. ),Proc. IAU Symp 124 on Observational Cosmology, New York: D. Reidel Publishing Company, 1986, 129.[6]Fang, L. Z., Zhou, Y. Y., Cheng F. Z. et al., Evolution of quasars with resolved components and determination of decel-eration parameter q0, Scientia Sinica, 1979, 22: 1292.[7]Cheng, K. S., Fan, J. H., Li, Y. et al., Do γ-ray burst associated with metal-rich quasars (ed. Cheng, K. S., Singh,H. P.), Proc. of The Pacific Rim Conference on Stellar Astrophysics, August 13-16, 1997, Houg Kong, 1997.[8]Davis, M., Geller, M. J., Huchra, J., The local mean mass density of the universe: new methods for studying galaxy clus-tering, Astrophys. J., 1978, 221: 1.[9]Gott, J. R., Turner, E. L., The mean luminosity and mass densities in the universe, Astrophys. J., 1976, 209: 1.[10]Shapiro, S. L., The density of matter in the form of galaxies, Astron. J., 1971, 76: 291.[11]Fang, L. Z., Hu, F. X., The large-scale inhomogeneities in the universe (eds. Yang, J., Zhu, C. S. ), Proceeding of A-cademia Sinica--Max-Plank Socity Workshop on High Energy Astrophyics Held in Nanjing, China, April 9-17, 1982,New York: Gordon and Breach Science Publishers S.A. 1982, 425[12]Baldwin, J. A

  1. Existence of shocklets in a two-dimensional supersonic mixing layer and its influence on the flow structure

    Institute of Scientific and Technical Information of China (English)

    CAO; Wei

    2001-01-01

    [1]Kristian, J. , Sandage, A. R. , Westphal, J., The extension of the Hubble diagram: Ⅱ. New redshifts and photometry of very distant galaxy clusters, Astrophys. J., 1978, 221: 383.[2]Sandage, A., The redshift-distant relation V. Galaxy co lors as functions of galactic latitude and redshift, Astrophys, J.,1973, 183: 711.[3]Qu, Q. Y., Qin, Z. H., Han, C. S. et al., A relation between magnitudes and redshifts of QSOs with strong interplanetary scientillation, Chinese Astron., 1979, 4: 97.[4]Tinsley, B. M. , The Galaxy counts, color-redshift relation, and related quantities as probes of cosmology and galactic evolu-tion, Astrophys. J., 1977, 211: 621.[5]Spinrad, H., Djorgovski, S., The status of the Hubble diagram in 1986 (eds. Hewitt, A. Burbidge, G. Fang, L. Z. ),Proc. IAU Symp 124 on Observational Cosmology, New York: D. Reidel Publishing Company, 1986, 129.[6]Fang, L. Z., Zhou, Y. Y., Cheng F. Z. et al., Evolution of quasars with resolved components and determination of decel-eration parameter q0, Scientia Sinica, 1979, 22: 1292.[7]Cheng, K. S., Fan, J. H., Li, Y. et al., Do γ-ray burst associated with metal-rich quasars (ed. Cheng, K. S., Singh,H. P.), Proc. of The Pacific Rim Conference on Stellar Astrophysics, August 13-16, 1997, Houg Kong, 1997.[8]Davis, M., Geller, M. J., Huchra, J., The local mean mass density of the universe: new methods for studying galaxy clus-tering, Astrophys. J., 1978, 221: 1.[9]Gott, J. R., Turner, E. L., The mean luminosity and mass densities in the universe, Astrophys. J., 1976, 209: 1.[10]Shapiro, S. L., The density of matter in the form of galaxies, Astron. J., 1971, 76: 291.[11]Fang, L. Z., Hu, F. X., The large-scale inhomogeneities in the universe (eds. Yang, J., Zhu, C. S. ), Proceeding of A-cademia Sinica--Max-Plank Socity Workshop on High Energy Astrophyics Held in Nanjing, China, April 9-17, 1982,New York: Gordon and Breach Science Publishers S.A. 1982, 425[12]Baldwin, J. A

  2. Kronecker limit formula for real quadratic number fields(III)

    Institute of Scientific and Technical Information of China (English)

    LU; Hongwen

    2001-01-01

    [1]Kristian, J. , Sandage, A. R. , Westphal, J., The extension of the Hubble diagram: Ⅱ. New redshifts and photometry of very distant galaxy clusters, Astrophys. J., 1978, 221: 383.[2]Sandage, A., The redshift-distant relation V. Galaxy co lors as functions of galactic latitude and redshift, Astrophys, J.,1973, 183: 711.[3]Qu, Q. Y., Qin, Z. H., Han, C. S. et al., A relation between magnitudes and redshifts of QSOs with strong interplanetary scientillation, Chinese Astron., 1979, 4: 97.[4]Tinsley, B. M. , The Galaxy counts, color-redshift relation, and related quantities as probes of cosmology and galactic evolu-tion, Astrophys. J., 1977, 211: 621.[5]Spinrad, H., Djorgovski, S., The status of the Hubble diagram in 1986 (eds. Hewitt, A. Burbidge, G. Fang, L. Z. ),Proc. IAU Symp 124 on Observational Cosmology, New York: D. Reidel Publishing Company, 1986, 129.[6]Fang, L. Z., Zhou, Y. Y., Cheng F. Z. et al., Evolution of quasars with resolved components and determination of decel-eration parameter q0, Scientia Sinica, 1979, 22: 1292.[7]Cheng, K. S., Fan, J. H., Li, Y. et al., Do γ-ray burst associated with metal-rich quasars (ed. Cheng, K. S., Singh,H. P.), Proc. of The Pacific Rim Conference on Stellar Astrophysics, August 13-16, 1997, Houg Kong, 1997.[8]Davis, M., Geller, M. J., Huchra, J., The local mean mass density of the universe: new methods for studying galaxy clus-tering, Astrophys. J., 1978, 221: 1.[9]Gott, J. R., Turner, E. L., The mean luminosity and mass densities in the universe, Astrophys. J., 1976, 209: 1.[10]Shapiro, S. L., The density of matter in the form of galaxies, Astron. J., 1971, 76: 291.[11]Fang, L. Z., Hu, F. X., The large-scale inhomogeneities in the universe (eds. Yang, J., Zhu, C. S. ), Proceeding of A-cademia Sinica--Max-Plank Socity Workshop on High Energy Astrophyics Held in Nanjing, China, April 9-17, 1982,New York: Gordon and Breach Science Publishers S.A. 1982, 425[12]Baldwin, J. A

  3. Molecular lines and continuum from W51A (I)

    Institute of Scientific and Technical Information of China (English)

    PEI; Chunchuan

    2001-01-01

    [1]Kristian, J. , Sandage, A. R. , Westphal, J., The extension of the Hubble diagram: Ⅱ. New redshifts and photometry of very distant galaxy clusters, Astrophys. J., 1978, 221: 383.[2]Sandage, A., The redshift-distant relation V. Galaxy co lors as functions of galactic latitude and redshift, Astrophys, J.,1973, 183: 711.[3]Qu, Q. Y., Qin, Z. H., Han, C. S. et al., A relation between magnitudes and redshifts of QSOs with strong interplanetary scientillation, Chinese Astron., 1979, 4: 97.[4]Tinsley, B. M. , The Galaxy counts, color-redshift relation, and related quantities as probes of cosmology and galactic evolu-tion, Astrophys. J., 1977, 211: 621.[5]Spinrad, H., Djorgovski, S., The status of the Hubble diagram in 1986 (eds. Hewitt, A. Burbidge, G. Fang, L. Z. ),Proc. IAU Symp 124 on Observational Cosmology, New York: D. Reidel Publishing Company, 1986, 129.[6]Fang, L. Z., Zhou, Y. Y., Cheng F. Z. et al., Evolution of quasars with resolved components and determination of decel-eration parameter q0, Scientia Sinica, 1979, 22: 1292.[7]Cheng, K. S., Fan, J. H., Li, Y. et al., Do γ-ray burst associated with metal-rich quasars (ed. Cheng, K. S., Singh,H. P.), Proc. of The Pacific Rim Conference on Stellar Astrophysics, August 13-16, 1997, Houg Kong, 1997.[8]Davis, M., Geller, M. J., Huchra, J., The local mean mass density of the universe: new methods for studying galaxy clus-tering, Astrophys. J., 1978, 221: 1.[9]Gott, J. R., Turner, E. L., The mean luminosity and mass densities in the universe, Astrophys. J., 1976, 209: 1.[10]Shapiro, S. L., The density of matter in the form of galaxies, Astron. J., 1971, 76: 291.[11]Fang, L. Z., Hu, F. X., The large-scale inhomogeneities in the universe (eds. Yang, J., Zhu, C. S. ), Proceeding of A-cademia Sinica--Max-Plank Socity Workshop on High Energy Astrophyics Held in Nanjing, China, April 9-17, 1982,New York: Gordon and Breach Science Publishers S.A. 1982, 425[12]Baldwin, J. A

  4. Pseudo almost periodic solutions for the systems of differential equations with piecewise constant argument

    Institute of Scientific and Technical Information of China (English)

    PIAO; Daxiong

    2001-01-01

    [1]Kristian, J. , Sandage, A. R. , Westphal, J., The extension of the Hubble diagram: Ⅱ. New redshifts and photometry of very distant galaxy clusters, Astrophys. J., 1978, 221: 383.[2]Sandage, A., The redshift-distant relation V. Galaxy co lors as functions of galactic latitude and redshift, Astrophys, J.,1973, 183: 711.[3]Qu, Q. Y., Qin, Z. H., Han, C. S. et al., A relation between magnitudes and redshifts of QSOs with strong interplanetary scientillation, Chinese Astron., 1979, 4: 97.[4]Tinsley, B. M. , The Galaxy counts, color-redshift relation, and related quantities as probes of cosmology and galactic evolu-tion, Astrophys. J., 1977, 211: 621.[5]Spinrad, H., Djorgovski, S., The status of the Hubble diagram in 1986 (eds. Hewitt, A. Burbidge, G. Fang, L. Z. ),Proc. IAU Symp 124 on Observational Cosmology, New York: D. Reidel Publishing Company, 1986, 129.[6]Fang, L. Z., Zhou, Y. Y., Cheng F. Z. et al., Evolution of quasars with resolved components and determination of decel-eration parameter q0, Scientia Sinica, 1979, 22: 1292.[7]Cheng, K. S., Fan, J. H., Li, Y. et al., Do γ-ray burst associated with metal-rich quasars (ed. Cheng, K. S., Singh,H. P.), Proc. of The Pacific Rim Conference on Stellar Astrophysics, August 13-16, 1997, Houg Kong, 1997.[8]Davis, M., Geller, M. J., Huchra, J., The local mean mass density of the universe: new methods for studying galaxy clus-tering, Astrophys. J., 1978, 221: 1.[9]Gott, J. R., Turner, E. L., The mean luminosity and mass densities in the universe, Astrophys. J., 1976, 209: 1.[10]Shapiro, S. L., The density of matter in the form of galaxies, Astron. J., 1971, 76: 291.[11]Fang, L. Z., Hu, F. X., The large-scale inhomogeneities in the universe (eds. Yang, J., Zhu, C. S. ), Proceeding of A-cademia Sinica--Max-Plank Socity Workshop on High Energy Astrophyics Held in Nanjing, China, April 9-17, 1982,New York: Gordon and Breach Science Publishers S.A. 1982, 425[12]Baldwin, J. A

  5. Generalized ergodicity

    Institute of Scientific and Technical Information of China (English)

    ZHENG; Zuohuan

    2001-01-01

    [1]Kristian, J. , Sandage, A. R. , Westphal, J., The extension of the Hubble diagram: Ⅱ. New redshifts and photometry of very distant galaxy clusters, Astrophys. J., 1978, 221: 383.[2]Sandage, A., The redshift-distant relation V. Galaxy co lors as functions of galactic latitude and redshift, Astrophys, J.,1973, 183: 711.[3]Qu, Q. Y., Qin, Z. H., Han, C. S. et al., A relation between magnitudes and redshifts of QSOs with strong interplanetary scientillation, Chinese Astron., 1979, 4: 97.[4]Tinsley, B. M. , The Galaxy counts, color-redshift relation, and related quantities as probes of cosmology and galactic evolu-tion, Astrophys. J., 1977, 211: 621.[5]Spinrad, H., Djorgovski, S., The status of the Hubble diagram in 1986 (eds. Hewitt, A. Burbidge, G. Fang, L. Z. ),Proc. IAU Symp 124 on Observational Cosmology, New York: D. Reidel Publishing Company, 1986, 129.[6]Fang, L. Z., Zhou, Y. Y., Cheng F. Z. et al., Evolution of quasars with resolved components and determination of decel-eration parameter q0, Scientia Sinica, 1979, 22: 1292.[7]Cheng, K. S., Fan, J. H., Li, Y. et al., Do γ-ray burst associated with metal-rich quasars (ed. Cheng, K. S., Singh,H. P.), Proc. of The Pacific Rim Conference on Stellar Astrophysics, August 13-16, 1997, Houg Kong, 1997.[8]Davis, M., Geller, M. J., Huchra, J., The local mean mass density of the universe: new methods for studying galaxy clus-tering, Astrophys. J., 1978, 221: 1.[9]Gott, J. R., Turner, E. L., The mean luminosity and mass densities in the universe, Astrophys. J., 1976, 209: 1.[10]Shapiro, S. L., The density of matter in the form of galaxies, Astron. J., 1971, 76: 291.[11]Fang, L. Z., Hu, F. X., The large-scale inhomogeneities in the universe (eds. Yang, J., Zhu, C. S. ), Proceeding of A-cademia Sinica--Max-Plank Socity Workshop on High Energy Astrophyics Held in Nanjing, China, April 9-17, 1982,New York: Gordon and Breach Science Publishers S.A. 1982, 425[12]Baldwin, J. A

  6. Effect of Mg and C contents in MgCNi3, and structure and superconductivity of MgCNi3-xCox

    Institute of Scientific and Technical Information of China (English)

    REN; Zhi'an

    2001-01-01

    [1]Kristian, J. , Sandage, A. R. , Westphal, J., The extension of the Hubble diagram: Ⅱ. New redshifts and photometry of very distant galaxy clusters, Astrophys. J., 1978, 221: 383.[2]Sandage, A., The redshift-distant relation V. Galaxy co lors as functions of galactic latitude and redshift, Astrophys, J.,1973, 183: 711.[3]Qu, Q. Y., Qin, Z. H., Han, C. S. et al., A relation between magnitudes and redshifts of QSOs with strong interplanetary scientillation, Chinese Astron., 1979, 4: 97.[4]Tinsley, B. M. , The Galaxy counts, color-redshift relation, and related quantities as probes of cosmology and galactic evolu-tion, Astrophys. J., 1977, 211: 621.[5]Spinrad, H., Djorgovski, S., The status of the Hubble diagram in 1986 (eds. Hewitt, A. Burbidge, G. Fang, L. Z. ),Proc. IAU Symp 124 on Observational Cosmology, New York: D. Reidel Publishing Company, 1986, 129.[6]Fang, L. Z., Zhou, Y. Y., Cheng F. Z. et al., Evolution of quasars with resolved components and determination of decel-eration parameter q0, Scientia Sinica, 1979, 22: 1292.[7]Cheng, K. S., Fan, J. H., Li, Y. et al., Do γ-ray burst associated with metal-rich quasars (ed. Cheng, K. S., Singh,H. P.), Proc. of The Pacific Rim Conference on Stellar Astrophysics, August 13-16, 1997, Houg Kong, 1997.[8]Davis, M., Geller, M. J., Huchra, J., The local mean mass density of the universe: new methods for studying galaxy clus-tering, Astrophys. J., 1978, 221: 1.[9]Gott, J. R., Turner, E. L., The mean luminosity and mass densities in the universe, Astrophys. J., 1976, 209: 1.[10]Shapiro, S. L., The density of matter in the form of galaxies, Astron. J., 1971, 76: 291.[11]Fang, L. Z., Hu, F. X., The large-scale inhomogeneities in the universe (eds. Yang, J., Zhu, C. S. ), Proceeding of A-cademia Sinica--Max-Plank Socity Workshop on High Energy Astrophyics Held in Nanjing, China, April 9-17, 1982,New York: Gordon and Breach Science Publishers S.A. 1982, 425[12]Baldwin, J. A

  7. Electronic structure of ZnO and its defects

    Institute of Scientific and Technical Information of China (English)

    XU; Pengshou

    2001-01-01

    [1]Kristian, J. , Sandage, A. R. , Westphal, J., The extension of the Hubble diagram: Ⅱ. New redshifts and photometry of very distant galaxy clusters, Astrophys. J., 1978, 221: 383.[2]Sandage, A., The redshift-distant relation V. Galaxy co lors as functions of galactic latitude and redshift, Astrophys, J.,1973, 183: 711.[3]Qu, Q. Y., Qin, Z. H., Han, C. S. et al., A relation between magnitudes and redshifts of QSOs with strong interplanetary scientillation, Chinese Astron., 1979, 4: 97.[4]Tinsley, B. M. , The Galaxy counts, color-redshift relation, and related quantities as probes of cosmology and galactic evolu-tion, Astrophys. J., 1977, 211: 621.[5]Spinrad, H., Djorgovski, S., The status of the Hubble diagram in 1986 (eds. Hewitt, A. Burbidge, G. Fang, L. Z. ),Proc. IAU Symp 124 on Observational Cosmology, New York: D. Reidel Publishing Company, 1986, 129.[6]Fang, L. Z., Zhou, Y. Y., Cheng F. Z. et al., Evolution of quasars with resolved components and determination of decel-eration parameter q0, Scientia Sinica, 1979, 22: 1292.[7]Cheng, K. S., Fan, J. H., Li, Y. et al., Do γ-ray burst associated with metal-rich quasars (ed. Cheng, K. S., Singh,H. P.), Proc. of The Pacific Rim Conference on Stellar Astrophysics, August 13-16, 1997, Houg Kong, 1997.[8]Davis, M., Geller, M. J., Huchra, J., The local mean mass density of the universe: new methods for studying galaxy clus-tering, Astrophys. J., 1978, 221: 1.[9]Gott, J. R., Turner, E. L., The mean luminosity and mass densities in the universe, Astrophys. J., 1976, 209: 1.[10]Shapiro, S. L., The density of matter in the form of galaxies, Astron. J., 1971, 76: 291.[11]Fang, L. Z., Hu, F. X., The large-scale inhomogeneities in the universe (eds. Yang, J., Zhu, C. S. ), Proceeding of A-cademia Sinica--Max-Plank Socity Workshop on High Energy Astrophyics Held in Nanjing, China, April 9-17, 1982,New York: Gordon and Breach Science Publishers S.A. 1982, 425[12]Baldwin, J. A

  8. Fourth order accurate compact scheme with group velocity control (GVC)

    Institute of Scientific and Technical Information of China (English)

    MA; Yanwen

    2001-01-01

    [1]Kristian, J. , Sandage, A. R. , Westphal, J., The extension of the Hubble diagram: Ⅱ. New redshifts and photometry of very distant galaxy clusters, Astrophys. J., 1978, 221: 383.[2]Sandage, A., The redshift-distant relation V. Galaxy co lors as functions of galactic latitude and redshift, Astrophys, J.,1973, 183: 711.[3]Qu, Q. Y., Qin, Z. H., Han, C. S. et al., A relation between magnitudes and redshifts of QSOs with strong interplanetary scientillation, Chinese Astron., 1979, 4: 97.[4]Tinsley, B. M. , The Galaxy counts, color-redshift relation, and related quantities as probes of cosmology and galactic evolu-tion, Astrophys. J., 1977, 211: 621.[5]Spinrad, H., Djorgovski, S., The status of the Hubble diagram in 1986 (eds. Hewitt, A. Burbidge, G. Fang, L. Z. ),Proc. IAU Symp 124 on Observational Cosmology, New York: D. Reidel Publishing Company, 1986, 129.[6]Fang, L. Z., Zhou, Y. Y., Cheng F. Z. et al., Evolution of quasars with resolved components and determination of decel-eration parameter q0, Scientia Sinica, 1979, 22: 1292.[7]Cheng, K. S., Fan, J. H., Li, Y. et al., Do γ-ray burst associated with metal-rich quasars (ed. Cheng, K. S., Singh,H. P.), Proc. of The Pacific Rim Conference on Stellar Astrophysics, August 13-16, 1997, Houg Kong, 1997.[8]Davis, M., Geller, M. J., Huchra, J., The local mean mass density of the universe: new methods for studying galaxy clus-tering, Astrophys. J., 1978, 221: 1.[9]Gott, J. R., Turner, E. L., The mean luminosity and mass densities in the universe, Astrophys. J., 1976, 209: 1.[10]Shapiro, S. L., The density of matter in the form of galaxies, Astron. J., 1971, 76: 291.[11]Fang, L. Z., Hu, F. X., The large-scale inhomogeneities in the universe (eds. Yang, J., Zhu, C. S. ), Proceeding of A-cademia Sinica--Max-Plank Socity Workshop on High Energy Astrophyics Held in Nanjing, China, April 9-17, 1982,New York: Gordon and Breach Science Publishers S.A. 1982, 425[12]Baldwin, J. A

  9. Polynomial solutions of quasi_homogeneous partial differential equations

    Institute of Scientific and Technical Information of China (English)

    LUO; Xuebo

    2001-01-01

    [1]Kristian, J. , Sandage, A. R. , Westphal, J., The extension of the Hubble diagram: Ⅱ. New redshifts and photometry of very distant galaxy clusters, Astrophys. J., 1978, 221: 383.[2]Sandage, A., The redshift-distant relation V. Galaxy co lors as functions of galactic latitude and redshift, Astrophys, J.,1973, 183: 711.[3]Qu, Q. Y., Qin, Z. H., Han, C. S. et al., A relation between magnitudes and redshifts of QSOs with strong interplanetary scientillation, Chinese Astron., 1979, 4: 97.[4]Tinsley, B. M. , The Galaxy counts, color-redshift relation, and related quantities as probes of cosmology and galactic evolu-tion, Astrophys. J., 1977, 211: 621.[5]Spinrad, H., Djorgovski, S., The status of the Hubble diagram in 1986 (eds. Hewitt, A. Burbidge, G. Fang, L. Z. ),Proc. IAU Symp 124 on Observational Cosmology, New York: D. Reidel Publishing Company, 1986, 129.[6]Fang, L. Z., Zhou, Y. Y., Cheng F. Z. et al., Evolution of quasars with resolved components and determination of decel-eration parameter q0, Scientia Sinica, 1979, 22: 1292.[7]Cheng, K. S., Fan, J. H., Li, Y. et al., Do γ-ray burst associated with metal-rich quasars (ed. Cheng, K. S., Singh,H. P.), Proc. of The Pacific Rim Conference on Stellar Astrophysics, August 13-16, 1997, Houg Kong, 1997.[8]Davis, M., Geller, M. J., Huchra, J., The local mean mass density of the universe: new methods for studying galaxy clus-tering, Astrophys. J., 1978, 221: 1.[9]Gott, J. R., Turner, E. L., The mean luminosity and mass densities in the universe, Astrophys. J., 1976, 209: 1.[10]Shapiro, S. L., The density of matter in the form of galaxies, Astron. J., 1971, 76: 291.[11]Fang, L. Z., Hu, F. X., The large-scale inhomogeneities in the universe (eds. Yang, J., Zhu, C. S. ), Proceeding of A-cademia Sinica--Max-Plank Socity Workshop on High Energy Astrophyics Held in Nanjing, China, April 9-17, 1982,New York: Gordon and Breach Science Publishers S.A. 1982, 425[12]Baldwin, J. A

  10. The role of Sm ions in optical storage of SrS

    Institute of Scientific and Technical Information of China (English)

    HE; Zhiyi

    2001-01-01

    [1]Kristian, J. , Sandage, A. R. , Westphal, J., The extension of the Hubble diagram: Ⅱ. New redshifts and photometry of very distant galaxy clusters, Astrophys. J., 1978, 221: 383.[2]Sandage, A., The redshift-distant relation V. Galaxy co lors as functions of galactic latitude and redshift, Astrophys, J.,1973, 183: 711.[3]Qu, Q. Y., Qin, Z. H., Han, C. S. et al., A relation between magnitudes and redshifts of QSOs with strong interplanetary scientillation, Chinese Astron., 1979, 4: 97.[4]Tinsley, B. M. , The Galaxy counts, color-redshift relation, and related quantities as probes of cosmology and galactic evolu-tion, Astrophys. J., 1977, 211: 621.[5]Spinrad, H., Djorgovski, S., The status of the Hubble diagram in 1986 (eds. Hewitt, A. Burbidge, G. Fang, L. Z. ),Proc. IAU Symp 124 on Observational Cosmology, New York: D. Reidel Publishing Company, 1986, 129.[6]Fang, L. Z., Zhou, Y. Y., Cheng F. Z. et al., Evolution of quasars with resolved components and determination of decel-eration parameter q0, Scientia Sinica, 1979, 22: 1292.[7]Cheng, K. S., Fan, J. H., Li, Y. et al., Do γ-ray burst associated with metal-rich quasars (ed. Cheng, K. S., Singh,H. P.), Proc. of The Pacific Rim Conference on Stellar Astrophysics, August 13-16, 1997, Houg Kong, 1997.[8]Davis, M., Geller, M. J., Huchra, J., The local mean mass density of the universe: new methods for studying galaxy clus-tering, Astrophys. J., 1978, 221: 1.[9]Gott, J. R., Turner, E. L., The mean luminosity and mass densities in the universe, Astrophys. J., 1976, 209: 1.[10]Shapiro, S. L., The density of matter in the form of galaxies, Astron. J., 1971, 76: 291.[11]Fang, L. Z., Hu, F. X., The large-scale inhomogeneities in the universe (eds. Yang, J., Zhu, C. S. ), Proceeding of A-cademia Sinica--Max-Plank Socity Workshop on High Energy Astrophyics Held in Nanjing, China, April 9-17, 1982,New York: Gordon and Breach Science Publishers S.A. 1982, 425[12]Baldwin, J. A

  11. Analysis of astronomical records of King Wu's Conquest

    Institute of Scientific and Technical Information of China (English)

    LIU; Ciyuan

    2001-01-01

    [1]Kristian, J. , Sandage, A. R. , Westphal, J., The extension of the Hubble diagram: Ⅱ. New redshifts and photometry of very distant galaxy clusters, Astrophys. J., 1978, 221: 383.[2]Sandage, A., The redshift-distant relation V. Galaxy co lors as functions of galactic latitude and redshift, Astrophys, J.,1973, 183: 711.[3]Qu, Q. Y., Qin, Z. H., Han, C. S. et al., A relation between magnitudes and redshifts of QSOs with strong interplanetary scientillation, Chinese Astron., 1979, 4: 97.[4]Tinsley, B. M. , The Galaxy counts, color-redshift relation, and related quantities as probes of cosmology and galactic evolu-tion, Astrophys. J., 1977, 211: 621.[5]Spinrad, H., Djorgovski, S., The status of the Hubble diagram in 1986 (eds. Hewitt, A. Burbidge, G. Fang, L. Z. ),Proc. IAU Symp 124 on Observational Cosmology, New York: D. Reidel Publishing Company, 1986, 129.[6]Fang, L. Z., Zhou, Y. Y., Cheng F. Z. et al., Evolution of quasars with resolved components and determination of decel-eration parameter q0, Scientia Sinica, 1979, 22: 1292.[7]Cheng, K. S., Fan, J. H., Li, Y. et al., Do γ-ray burst associated with metal-rich quasars (ed. Cheng, K. S., Singh,H. P.), Proc. of The Pacific Rim Conference on Stellar Astrophysics, August 13-16, 1997, Houg Kong, 1997.[8]Davis, M., Geller, M. J., Huchra, J., The local mean mass density of the universe: new methods for studying galaxy clus-tering, Astrophys. J., 1978, 221: 1.[9]Gott, J. R., Turner, E. L., The mean luminosity and mass densities in the universe, Astrophys. J., 1976, 209: 1.[10]Shapiro, S. L., The density of matter in the form of galaxies, Astron. J., 1971, 76: 291.[11]Fang, L. Z., Hu, F. X., The large-scale inhomogeneities in the universe (eds. Yang, J., Zhu, C. S. ), Proceeding of A-cademia Sinica--Max-Plank Socity Workshop on High Energy Astrophyics Held in Nanjing, China, April 9-17, 1982,New York: Gordon and Breach Science Publishers S.A. 1982, 425[12]Baldwin, J. A

  12. On large increments of a two-parameter fractional Wiener process

    Institute of Scientific and Technical Information of China (English)

    ZHANG; Lixin

    2001-01-01

    [1]Kristian, J. , Sandage, A. R. , Westphal, J., The extension of the Hubble diagram: Ⅱ. New redshifts and photometry of very distant galaxy clusters, Astrophys. J., 1978, 221: 383.[2]Sandage, A., The redshift-distant relation V. Galaxy co lors as functions of galactic latitude and redshift, Astrophys, J.,1973, 183: 711.[3]Qu, Q. Y., Qin, Z. H., Han, C. S. et al., A relation between magnitudes and redshifts of QSOs with strong interplanetary scientillation, Chinese Astron., 1979, 4: 97.[4]Tinsley, B. M. , The Galaxy counts, color-redshift relation, and related quantities as probes of cosmology and galactic evolu-tion, Astrophys. J., 1977, 211: 621.[5]Spinrad, H., Djorgovski, S., The status of the Hubble diagram in 1986 (eds. Hewitt, A. Burbidge, G. Fang, L. Z. ),Proc. IAU Symp 124 on Observational Cosmology, New York: D. Reidel Publishing Company, 1986, 129.[6]Fang, L. Z., Zhou, Y. Y., Cheng F. Z. et al., Evolution of quasars with resolved components and determination of decel-eration parameter q0, Scientia Sinica, 1979, 22: 1292.[7]Cheng, K. S., Fan, J. H., Li, Y. et al., Do γ-ray burst associated with metal-rich quasars (ed. Cheng, K. S., Singh,H. P.), Proc. of The Pacific Rim Conference on Stellar Astrophysics, August 13-16, 1997, Houg Kong, 1997.[8]Davis, M., Geller, M. J., Huchra, J., The local mean mass density of the universe: new methods for studying galaxy clus-tering, Astrophys. J., 1978, 221: 1.[9]Gott, J. R., Turner, E. L., The mean luminosity and mass densities in the universe, Astrophys. J., 1976, 209: 1.[10]Shapiro, S. L., The density of matter in the form of galaxies, Astron. J., 1971, 76: 291.[11]Fang, L. Z., Hu, F. X., The large-scale inhomogeneities in the universe (eds. Yang, J., Zhu, C. S. ), Proceeding of A-cademia Sinica--Max-Plank Socity Workshop on High Energy Astrophyics Held in Nanjing, China, April 9-17, 1982,New York: Gordon and Breach Science Publishers S.A. 1982, 425[12]Baldwin, J. A

  13. Extremal hexagonal chains concerning largest eigenvalue

    Institute of Scientific and Technical Information of China (English)

    ZHANG; Lianzhu

    2001-01-01

    [1]Kristian, J. , Sandage, A. R. , Westphal, J., The extension of the Hubble diagram: Ⅱ. New redshifts and photometry of very distant galaxy clusters, Astrophys. J., 1978, 221: 383.[2]Sandage, A., The redshift-distant relation V. Galaxy co lors as functions of galactic latitude and redshift, Astrophys, J.,1973, 183: 711.[3]Qu, Q. Y., Qin, Z. H., Han, C. S. et al., A relation between magnitudes and redshifts of QSOs with strong interplanetary scientillation, Chinese Astron., 1979, 4: 97.[4]Tinsley, B. M. , The Galaxy counts, color-redshift relation, and related quantities as probes of cosmology and galactic evolu-tion, Astrophys. J., 1977, 211: 621.[5]Spinrad, H., Djorgovski, S., The status of the Hubble diagram in 1986 (eds. Hewitt, A. Burbidge, G. Fang, L. Z. ),Proc. IAU Symp 124 on Observational Cosmology, New York: D. Reidel Publishing Company, 1986, 129.[6]Fang, L. Z., Zhou, Y. Y., Cheng F. Z. et al., Evolution of quasars with resolved components and determination of decel-eration parameter q0, Scientia Sinica, 1979, 22: 1292.[7]Cheng, K. S., Fan, J. H., Li, Y. et al., Do γ-ray burst associated with metal-rich quasars (ed. Cheng, K. S., Singh,H. P.), Proc. of The Pacific Rim Conference on Stellar Astrophysics, August 13-16, 1997, Houg Kong, 1997.[8]Davis, M., Geller, M. J., Huchra, J., The local mean mass density of the universe: new methods for studying galaxy clus-tering, Astrophys. J., 1978, 221: 1.[9]Gott, J. R., Turner, E. L., The mean luminosity and mass densities in the universe, Astrophys. J., 1976, 209: 1.[10]Shapiro, S. L., The density of matter in the form of galaxies, Astron. J., 1971, 76: 291.[11]Fang, L. Z., Hu, F. X., The large-scale inhomogeneities in the universe (eds. Yang, J., Zhu, C. S. ), Proceeding of A-cademia Sinica--Max-Plank Socity Workshop on High Energy Astrophyics Held in Nanjing, China, April 9-17, 1982,New York: Gordon and Breach Science Publishers S.A. 1982, 425[12]Baldwin, J. A

  14. Recovery of band limited functions via cardinal splines

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    [1]Kristian, J. , Sandage, A. R. , Westphal, J., The extension of the Hubble diagram: Ⅱ. New redshifts and photometry of very distant galaxy clusters, Astrophys. J., 1978, 221: 383.[2]Sandage, A., The redshift-distant relation V. Galaxy co lors as functions of galactic latitude and redshift, Astrophys, J.,1973, 183: 711.[3]Qu, Q. Y., Qin, Z. H., Han, C. S. et al., A relation between magnitudes and redshifts of QSOs with strong interplanetary scientillation, Chinese Astron., 1979, 4: 97.[4]Tinsley, B. M. , The Galaxy counts, color-redshift relation, and related quantities as probes of cosmology and galactic evolu-tion, Astrophys. J., 1977, 211: 621.[5]Spinrad, H., Djorgovski, S., The status of the Hubble diagram in 1986 (eds. Hewitt, A. Burbidge, G. Fang, L. Z. ),Proc. IAU Symp 124 on Observational Cosmology, New York: D. Reidel Publishing Company, 1986, 129.[6]Fang, L. Z., Zhou, Y. Y., Cheng F. Z. et al., Evolution of quasars with resolved components and determination of decel-eration parameter q0, Scientia Sinica, 1979, 22: 1292.[7]Cheng, K. S., Fan, J. H., Li, Y. et al., Do γ-ray burst associated with metal-rich quasars (ed. Cheng, K. S., Singh,H. P.), Proc. of The Pacific Rim Conference on Stellar Astrophysics, August 13-16, 1997, Houg Kong, 1997.[8]Davis, M., Geller, M. J., Huchra, J., The local mean mass density of the universe: new methods for studying galaxy clus-tering, Astrophys. J., 1978, 221: 1.[9]Gott, J. R., Turner, E. L., The mean luminosity and mass densities in the universe, Astrophys. J., 1976, 209: 1.[10]Shapiro, S. L., The density of matter in the form of galaxies, Astron. J., 1971, 76: 291.[11]Fang, L. Z., Hu, F. X., The large-scale inhomogeneities in the universe (eds. Yang, J., Zhu, C. S. ), Proceeding of A-cademia Sinica--Max-Plank Socity Workshop on High Energy Astrophyics Held in Nanjing, China, April 9-17, 1982,New York: Gordon and Breach Science Publishers S.A. 1982, 425[12]Baldwin, J. A

  15. ASPECTOS RELEVANTES DA APROXIMAÇÃO ENTRE BRASIL E CHINA: UMA ABORDAGEM ANALÍTICA [doi: 10.5329/RECADM.20050401009

    Directory of Open Access Journals (Sweden)

    Silvio Aparecido Crepaldi

    2005-05-01

    Full Text Available Normal 0 21 false false false PT-BR X-NONE X-NONE MicrosoftInternetExplorer4 RESUMO Nos últimos anos, cresceu notavelmente o interesse mútuo entre o Brasil e a China. Na década de 1990 ambos os países se esforçaram para promover a multi-polarização do poder mundial e fortalecer a cooperação entre países em desenvolvimento. Brasil e China trabalham com vistas à consolidação de uma parceria estratégica, o que tem impulsionado as relações bilaterais; mas há ainda desafios a serem superados. Com esta realidade surge uma lacuna na bibliografia sobre os aspectos relevantes da aproximação Brasil e China. Assim, a carência de bibliografias voltadas ao assunto que incluam o estudo desta aproximação e seus reflexos, motiva à pesquisa visando sanar essas deficiências. Pretende-se analisar as relações comerciais sino-brasileiras de 1984 a 2002 e explorar o significado do conceito de parceria estratégica no relacionamento dos dois países. Antes disso, contudo, são indispensáveis algumas ponderações extraídas da sua análise global, permitindo a melhor reflexão e apontamento de conclusões sobre as relevantes matérias tratadas na referida aproximação Brasil e China. Em conseqüência do cenário exposto, a problemática pode ser sintetizada na seguinte questão: "como Brasil e China deveriam interagir entre si para obter uma inserção mutuamente vantajosa no mundo globalizado?". As informações referentes ao tema aproximação entre Brasil e China foram obtidas mediante pesquisa bibliográfica. O volume das transações comerciais entre Brasil e China vem evoluindo rapidamente e a China tornou-se recentemente o maior parceiro comercial do Brasil na Ásia. Há ainda enormes potencialidades comerciais a serem exploradas. Ao mesmo tempo, a economia chinesa consegue gerar empregos urbanos em escala astronômica. Somente nos primeiros 9 (nove meses deste ano, foram criados cerca de 8 milhões de postos de trabalho nas cidades

  16. Brennand: resonancia y universalidad de las formas Brennand: resonance and the univesality of the forms

    Directory of Open Access Journals (Sweden)

    G. CECILIA TORO

    2001-03-01

    Full Text Available Este trabajo propone la búsqueda y exposición de patrones de formas, tanto de algunas obras producidas por la naturaleza como de algunas de las obras producidas por la mano del hombre, quien como un microcosmos, que forma parte de la naturaleza recrea el macrocosmos. En una cultura en que el hombre ha perdido contacto con la naturaleza, con sus semejantes y con sus orígenes, otro objetivo de este trabajo es re emparentar al hombre con la naturaleza de la que forma parte. Se pretende mostrar al hombre, como un fractal del Universo, que es capaz de recrear, independientemente del tiempo, del espacio y de la escala de magnitudes, las mismas formas que crea el Universo, con la fuerza de la belleza en toda su pureza y en todo lo terrible con que a veces se nos presenta su aspecto. La belleza, así como la religión o como la pureza, tiene un poder redentor y el hombre anhela los paraísos perdidos. Cuando se amplia nuestra capacidad para percibir la belleza ya estamos en camino cierto, ya estamos en un camino que nos cambia desde un estado de conciencia a otro, ya estamos en un camino de regreso a la unidad. En el presente estudio se exponen algunas formas durante la diferenciación de un platelminto, Mesocestoides corti, obtenidas mediante microscopía de barrido y se exponen algunas obras de un hombre, Francisco Brennand, ganador del premio Gabriela Mistral 1993, el mayor premio dado en artes plásticas en América. Brennand, como un holograma, con un único referencial: el Universo ha recreado un Universo biológico y de increíble belleza desde su interior. En este trabajo, se pretende además exponer como, a través de la historia de nuestra cultura, el hombre justificó el anhelo y la certeza de universalidad, generando explicaciones filosóficas, psicológicas, biológicas, físicas, matemáticas, astronómicas y artísticasThis work proposes for the search and exposition of patterns of forms as they appear in nature as well as those

  17. Editorial

    Science.gov (United States)

    Dimitrijevic, M. S.; Popovic, L. C.

    The present issue of SERBIAN ASTRONOMICAL JOURNAL is the last one edited by the two of us. We resigned not because we were tired of our service to the astronomical community but due to the old tradition of the Belgrade Astronomical Observatory that its Director is automatically the Editor-in-Chief of its publications. We therefore gladly give the opportunity to the new Director, in charge since July 1st. 2002, to organize the publishing activity according to his conceptions. One of us (M.S.D.) was appointed Editor on January 1st. 1984 (from No. 135), becoming the Editor-in-Chief in 1987 (from No. 137). The other one (L.C.P.) is the Editor since 1994 (from No. 150). During this period the Bulletin de l'Observatoire Astronomique de Belgrade merged with the Publications of the Department of Astronomy, changing its name into Bulletin Astronomique de Belgrade from No. 145 in 1992, to finally become Serbian Astronomical Journal in 1998, from No. 157. Accordingly, of a "Bulletin" we made a "Journal". For example, in the period 1971-1984 (Nos. 125-134) in Bull. Obs. Astron. Belgrade, practically only the associates of the Belgade Observatory published their papers, save for a few individuals from the Belgrade University. We found within this period the name of one sole foreign astronomer - from the USSR - namely V. A. Fomin, among the authors. In the period 1985-2002 in the Serbian Astronomical Journal published their communications not only astronomers from Yugoslavia but also from Belgium, China, France, Italy, Moldova, Romania, Russia, Spain, Ukraine, USA. Our authors from outside of Yugoslavia are: J. P. Anosova C. Beuyninx Cristina Blaga Paul A. Blaga Veronique Bommier N. M. Bronnikov Alberto Celino Pierre Cugnon D. R. Davis Henry Debehogne Veronique Dehant P. Farinella Alex Gaina R. I. Gumerov R. S. Izmailov V. B. Kapkov F. F. Khalikhevich S. A. Kilioner Tatiana R. Kirian N. G. Litkevich Evencio G. Mediavilla O. Mihai Andrea Milani Vasile Mioc Jose A. Munoz Viktor V

  18. Inhomogeneous molecular ring around the B[e] supergiant LHA 120-S 73

    Science.gov (United States)

    Kraus, M.; Cidale, L. S.; Arias, M. L.; Maravelias, G.; Nickeler, D. H.; Torres, A. F.; Borges Fernandes, M.; Aret, A.; Curé, M.; Vallverdú, R.; Barbá, R. H.

    2016-10-01

    line profile is strongly variable in both width and shape and resembles of those seen in non-radially pulsating stars. A proper determination of the real underlying stellar rotation velocity is hence not possible. Conclusions: The existence of multiple stable and clumpy rings of alternating density recalls ring structures around planets. Although there is currently insufficient observational evidence, it is tempting to propose a scenario with one (or more) minor bodies or planets revolving around LHA 120-S 73 and stabilizing the ring system, in analogy to the shepherd moons in planetary systems. Based on observations: (1) with the 1.52-m and 2.2-m telescopes at the European Southern Observatory (La Silla, Chile), under the programme 076.D-0609(A) and under the agreement with the Observatório Nacional-MCT (Brazil); (2) at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the Science and Technology Facilities Council (United Kingdom), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministério da Ciência, Tecnologia e Inovação (Brazil) and Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina), under the programmes GS-2004B-Q-54, GS-2010B-Q-31, and GS-2012B-Q-90; (3) at Complejo Astronómico El Leoncito operated under agreement between the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina and the National Universities of La Plata, Córdoba and San Juan (Visiting Astronomer: A.F.T.); and (4) with the du Pont Telescope at Las Campanas Observatory, Chile, under the programme CNTAC 2008-02 (Visiting Astronomer: R.B. and A.F.T.).Presented spectroscopic data are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc

  19. Young and Exotic Stellar Zoo

    Science.gov (United States)

    2005-03-01

    constellation Ara (the Altar). It was discovered in 1961 from Australia by Swedish astron

  20. A proposed contents astronomy for basic education

    Science.gov (United States)

    Albrecht, E.; Voelzke, M. R.

    2014-08-01

    A Astronomia é um tema que sempre exerceu fascínio sobre as pessoas de um modo geral. Conhecer e estudar o que há nos “céus”, além de nossos olhos, continua sendo instigador e de grande interesse. Baseado nestas justificativas desenvolveu-se uma pesquisa de Doutorado, na qual, o objetivo principal foi investigar sobre a presença dos conteúdos de Astronomia nas Propostas Curriculares da região Sul do Brasil, a saber, os estados de Paraná, Rio Grande do Sul e Santa Catarina e, posterior comparação com os Parâmetros Curriculares Nacionais (PCN) que trazem propostas de conteúdos para toda a Educação Básica brasileira. Tal investigação pautou-se na abordagem de caráter qualitativo e utilizouse para tal da Análise de Conteúdos (Bardin, 2011), que possibilitou a construção de quatro categorias, nas quais os conteúdos astronômicos foram agrupados: Terra, Sistema Solar, Via Láctea e Universo. Após a leitura, coleta de dados, construção de categorias, observou-se a dicotomia na apresentação destes conteúdos. As propostas curriculares analisadas foram as de Geografia, Ciências e Física dos estados do Paraná (2008), Rio Grande do Sul (2009) e de Santa Catarina (1998), responsáveis pelo trabalho com Astronomia nestes estados. No Ensino Fundamental, a proposta curricular do estado do Paraná apresenta conteúdos ligados à Astronomia desde o sexto ano até o nono ano, como conteúdo do primeiro bimestre, o que também é apresentado na proposta curricular do estado do Rio Grande do Sul, porém, este, não divide os conteúdos por bimestre e nem por ano, mas por ciclos, sexto e sétimo anos como primeiro ciclo e oitavo e nono anos como segundo ciclo, deixando livre para o professor estruturar sua sequência de conteúdos. A proposta curricular de Santa Catarina não apresenta estes conteúdos de maneira explícita, não divide dos conteúdos nem por ano, nem por série, traz uma sequência de conteúdos para serem trabalhados ao longo dos