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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. The RadioAstron Dedicated DiFX Distribution

    Directory of Open Access Journals (Sweden)

    Gabriele Bruni

    2016-10-01

    Full Text Available Distributed FX-architecture (DiFX is a software Very Long Baseline Interferometry (VLBI correlator currently adopted by several main correlation sites around the globe. After the launch of the RadioAstron Space-VLBI mission in 2011, an extension was necessary to handle processing of an orbiting antenna, to be correlated with supporting ground arrays. Here, we present a branch of the main DiFX distribution (2.4, uploaded on the publicly available repository during July 2016, that the Max Planck Institute for Radio Astronomy (MPIfR developed to process data of the three key active galactic nuclei (AGN-imaging RadioAstron science projects, as well as part of the AGN survey project, and General Observing Time (GOT projects proposed since Announcement of Opportunity 2 (AO-2, July 2014–July 2015. It can account for general relativistic correction of an orbiting antenna with variable position/velocity, providing a routine to convert the native RadioAstron Data Format (RDF format to the more common Mark5 B (M5B. The possibility of introducing a polynomial clock allows one to mitigate the effects of spacecraft acceleration terms in near-perigee observations. Additionally, since for the first time polarimetry on space-baselines is available thanks to RadioAstron, this DiFX branch allows one to include the spacecraft orientation information at the correlation stage, in order to perform proper polarization calibration during data reduction. Finally, a fringe-finding algorithm able to manage an arbitrarily large fringe-search window is included, allowing one to increase the search space normally adopted by common software packages like HOPS.

  5. 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.

  6. Aniversarios astronómicos en Cananea, Sonora

    Directory of Open Access Journals (Sweden)

    Raúl Pérez – Enríquez

    2013-06-01

    Full Text Available El 21 de marzo de 1913, en la ciudad de México, nació Guillermo Haro Barraza y el 27 de abril de 1988, se inauguró el Observatorio Astrofísico Guillermo Haro, en Cananea, Sonora. Estos dos muy importantes aniversarios astronómicos se conmemoraron el pasado 27 de abril. Aquí se da cuenta de la relevancia de ambos festejos, de la fructuosa vida del homenajeado y de las actividades desarrolladas ese día allá donde está instalada “Una mina de estrellas”.

  7. Guía astronómica

    OpenAIRE

    2003-01-01

    Esta Guía Astronómica es una versión de mis conferencias en el Taller de Astronomía desde 1985 y en el curso de Contexto en Astronomía desde 2000, dos actividades ofrecidas por la Universidad Nacional de Colombia en Manizales, como espacios disponibles para la comunidad académica y para los aficionados a la astronomía. Por esa razón, este texto propio de la vida universitaria, ha evolucionado hasta encontrar el lenguaje sencillo y la medida adecuada en la extensión y profundidad de los tem...

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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....

  14. 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

  15. 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.

  16. Sitios de interés astronómico en el Noroeste Argentino

    Science.gov (United States)

    Recabarren, P.; Muriel, H.; Mosconi, M.; García Lambas, D.; Sarazin, M.; Giovanelli, R.

    Se presenta la distribución geográfica de nubosidad en la región comprendida entre las latitudes 23o y 28o Sur, y las longitudes 66o y 69o Oeste, obtenida a partir del análisis de imágenes GOES, tomadas durante los años 1999 al 2002 inclusive. Del análisis de esta información, se revelan como de gran interés las áreas circundantes a los Salares de Antofalla y de Arizaro, en la región de la Puna, en las provincias de Catamarca y Salta. Se hacen comentarios sobre sitios explorados en estas regiones y sobre las posibilidades de asentamientos de grandes facilidades astronómicas en la región. Se complementa la presentación con información tectónica, topográfica y logística de relevante importancia y, finalmente, se discute sobre la selección de emplazamientos para dos estaciones meteorológicas automáticas de la Universidad de Cornell, en las áreas mencionadas.

  17. The Guieloa Adaptive Optics System for the Observatorio Astronómico Nacional

    Directory of Open Access Journals (Sweden)

    A.M. Watson

    2007-01-01

    Full Text Available Se describen los avances para construir un sistema de ptica adaptativa para el telescopio de 2.1-metros del Observatorio Astron mico Nacional en la Sierra de San Pedro M rtir. El sistema utilizar un espejo deformable de tipo bimorfo de 19 elementos montado sobre una plataforma articulada y un sensor de frente de onda tipo curvatura para estrellas gu a naturales. Guieloa tendr dos modos de operaci n. En modo de ptica adaptativa se espera que proporcionar una correcci n excelente en longitudes de onda mayores a 1.0 m y una correcci n buena entre 0.6 y 0.9 m dependiendo de las condiciones del seeing, aunque la cobertura del cielo ser restringida. En el modo de ptica activa y guiado r pido se espera que proporcionar im genes en el l mite del seeing natural o mejor, y con una cobertura de cielo mucho mayor. Actualmente el sistema se encuentra en la fase de pruebas en el laboratorio y se espera que sea entregado en el observatorio en 2009

  18. 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.

  19. Centro astronómico de Calar-Alto Almería – España

    Directory of Open Access Journals (Sweden)

    Margarit, Salvador

    1980-08-01

    Full Text Available The Basic Agreement of Cooperation in Scientific Research and Technological development signed by the Spanish and West German governments in 1970, served as a framework for the agreement signed in 1972 by the National Astronomical Commission and the Max-Planck Society, for the setting up of the «Spanish-German Astronomical Centre». Construction work was started in 1973 on the Calar-Alto (2,168 m, the highest point in the Sierra de los Filabres in the province of Almería. At present the last of the domed buildings, which is intented to accommodate a 3.5 m diameter Telescope and should go into operation in 1983, is at the completion stage. By this date all work will have been completed, with four domed buildings for telescopes of different sizes and the buildings for laboratory, living quarters, services and workshops needed for the use of the scientific instruments. The 1.52 m diameter National Astronomical Observatory telescope has been installed in a separate building beside the infrastructure of the Spanish-German Astronomical Centre.

    El Convenio Básico de Cooperación en la Investigación Científica y en el Desarrollo tecnológico suscrito entre los gobiernos de España y de la República Federal de Alemania en 1970, sirvió de marco para el acuerdo firmado en 1972 entre la Comisión Nacional de Astronomía y la Sociedad Max-Planck, para el establecimiento del «Centro Astronómico» Hispano-Alemán. En 1973 se iniciaron los trabajos de Obras en Calar-Alto (2.168 m cota máxima de la Sierra de los Filabres en la provincia de Almena. Actualmente se halla en fase de terminación el último de los edificios de Cúpula destinado a albergar un Telescopio de 3,5 m de diámetro y cuya puesta en servicio se prevé en 1983. Para entonces quedará culminada la realización completa con cuatro edificios de Cúpula para telescopios de diferentes tamaños y las edificaciones destinadas a laboratorio, residencia, viviendas, servicios y

  20. Recent Site Testing Campaign at the Observatorio Astronómico Nacional in San Pedro Mártir

    Directory of Open Access Journals (Sweden)

    R. Michel

    2003-01-01

    Full Text Available Hemos llevado a cabo un nuevo programa para medir el seeing en el Observatorio Astronómico Nacional en San Pedro Mártir. Los resultados obtenidos durante un período de dos años, arrojan una calidad de imagen con mediana de 0.57 segundos de arco y un primer cuartil de 0.46 segundos de arco. Mostramos también que el seeing puede ser muy estable durante toda la noche bajo condiciones excelentes. Las mejores medidas arrojan una mediana de 0.37 segundos de arco, obtenidas de observaciones continuas durante casi nueve horas. Nuestros resultados son comparados con un estudio previo del sitio, encontrándose resultados muy similares.

  1. The Double-Astrograph Telescope is working at the Observatorio Astronómico Nacional of Venezuela

    Science.gov (United States)

    Abad, C.; Barroeta, G.; Schenner, H.; Plaza, L.; Ramírez, P.; Lacruz, E.

    2009-05-01

    The Double Astrograph telescope (two 0.5 m lenses) in the Observatorio Astronómico Nacional of Venezuela (OAN) will soon be available for observations to the astronomical comunity. Despite of being placed at the OAN since thirty years ago, together with the three other telescopes installed there, it was not fully assembled. Recent engineering work on it, has got to mecanically balance the telescope and set control of the electric motors for the motion of this instrument. The current positioning and guided motions of the telescope allow for an observational quantification of the different aberrations of the optical system of the instrument. With this in mind, selected fields of stars have been observed with a CCD camera, that was installed at different locations on the focal plane. Here we show a summary of the technical operations and the first observational results, aimed at evaluating the potential of the Double Astrograph for future scientific investigations.

  2. 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...

  3. RadioAstron Observations of the Quasar 3C273: a Challenge to the Brightness Temperature Limit

    CERN Document Server

    Kovalev, Y Y; Kellermann, K I; Lobanov, A P; Johnson, M D; Gurvits, L I; Voitsik, P A; Zensus, J A; Anderson, J M; Bach, U; Jauncey, D L; Ghigo, F; Ghosh, T; Kraus, A; Kovalev, Yu A; Lisakov, M M; Petrov, L Yu; Romney, J D; Salter, C J; Sokolovsky, K V

    2016-01-01

    Inverse Compton cooling limits the brightness temperature of the radiating plasma to a maximum of $10^{11.5}$ K. Relativistic boosting can increase its observed value, but apparent brightness temperatures much in excess of $10^{13}$ K are inaccessible using ground-based very long baseline interferometry (VLBI) at any wavelength. We present observations of the quasar 3C273, 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 $\\mu$as (2.7 light months) and brightness temperature in excess of $10^{13}$ K. These measurements challenge our understanding of the non-thermal continuum emission in the vicinity of supermassive black holes and require much higher jet speeds than are observed.

  4. 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 meters 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 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 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.

  5. "RadioAstron"-A telescope with a size of 300 000 km: Main parameters and first observational results

    Science.gov (United States)

    Kardashev, N. S.; Khartov, V. V.; Abramov, V. V.; Avdeev, V. Yu.; Alakoz, A. V.; Aleksandrov, Yu. A.; Ananthakrishnan, S.; Andreyanov, V. V.; Andrianov, A. S.; Antonov, N. M.; Artyukhov, M. I.; Arkhipov, M. Yu.; Baan, W.; Babakin, N. G.; Babyshkin, V. E.; Bartel', N.; Belousov, K. G.; Belyaev, A. A.; Berulis, J. J.; Burke, B. F.; Biryukov, A. V.; Bubnov, A. E.; Burgin, M. S.; Busca, G.; Bykadorov, A. A.; Bychkova, V. S.; Vasil'kov, V. I.; Wellington, K. J.; Vinogradov, I. S.; Wietfeldt, R.; Voitsik, P. A.; Gvamichava, A. S.; Girin, I. A.; Gurvits, L. I.; Dagkesamanskii, R. D.; D'Addario, L.; Giovannini, G.; Jauncey, D. L.; Dewdney, P. E.; D'yakov, A. A.; Zharov, V. E.; Zhuravlev, V. I.; Zaslavskii, G. S.; Zakhvatkin, M. V.; Zinov'ev, A. N.; Ilinen, Yu.; Ipatov, A. V.; Kanevskii, B. Z.; Knorin, I. A.; Casse, J. L.; Kellermann, K. I.; Kovalev, Yu. A.; Kovalev, Yu. Yu.; Kovalenko, A. V.; Kogan, B. L.; Komaev, R. V.; Konovalenko, A. A.; Kopelyanskii, G. D.; Korneev, Yu. A.; Kostenko, V. I.; Kotik, A. N.; Kreisman, B. B.; Kukushkin, A. Yu.; Kulishenko, V. F.; Cooper, D. N.; Kut'kin, A. M.; Cannon, W. H.; Larionov, M. G.; Lisakov, M. M.; Litvinenko, L. N.; Likhachev, S. F.; Likhacheva, L. N.; Lobanov, A. P.; Logvinenko, S. V.; Langston, G.; McCracken, K.; Medvedev, S. Yu.; Melekhin, M. V.; Menderov, A. V.; Murphy, D. W.; Mizyakina, T. A.; Mozgovoi, Yu. V.; Nikolaev, N. Ya.; Novikov, B. S.; Novikov, I. D.; Oreshko, V. V.; Pavlenko, Yu. K.; Pashchenko, I. N.; Ponomarev, Yu. N.; Popov, M. V.; Pravin-Kumar, A.; Preston, R. A.; Pyshnov, V. N.; Rakhimov, I. A.; Rozhkov, V. M.; Romney, J. D.; Rocha, P.; Rudakov, V. A.; Räisänen, A.; Sazankov, S. V.; Sakharov, B. A.; Semenov, S. K.; Serebrennikov, V. A.; Schilizzi, R. T.; Skulachev, D. P.; Slysh, V. I.; Smirnov, A. I.; Smith, J. G.; Soglasnov, V. A.; Sokolovskii, K. V.; Sondaar, L. H.; Stepan'yants, V. A.; Turygin, M. S.; Turygin, S. Yu.; Tuchin, A. G.; Urpo, S.; Fedorchuk, S. D.; Finkel'shtein, A. M.; Fomalont, E. B.; Fejes, I.; Fomina, A. N.; Khapin, Yu. B.; Tsarevskii, G. S.; Zensus, J. A.; Chuprikov, A. A.; Shatskaya, M. V.; Shapirovskaya, N. Ya.; Sheikhet, A. I.; Shirshakov, A. E.; Schmidt, A.; Shnyreva, L. A.; Shpilevskii, V. V.; Ekers, R. D.; Yakimov, V. E.

    2013-03-01

    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 formation of stars and planetary systems in our and other galaxies, interplanetary and interstellar plasma, and the gravitational field of the Earth. The results of ground-based and inflight tests of the space radio telescope carried out in both autonomous and ground-space interferometric regimes are reported. The derived characteristics are in agreement with the main requirements of the project. The astrophysical science program has begun.

  6. 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...

  7. RadioAstron Studies of the Nearby, Turbulent Interstellar Plasma With the Longest Space-Ground Interferometer Baseline

    CERN Document Server

    Smirnova, T V; Popov, M V; Gwinn, C R; Anderson, J M; Andrianov, A S; Bartel, N; Deller, A; Johnson, M D; Joshi, B C; Kardashev, N S; Karuppusamy, R; Kovalev, Y Y; Kramer, M; Soglasnov, V A; Zensus, J A; Zhuravlev, V I

    2014-01-01

    RadioAstron space-ground VLBI observations of the pulsar B0950+08, conducted with the 10-m space radio telescope in conjunction with the Arecibo 300-m telescope and Westerbork Synthesis Radio Telescope at a frequency of 324 MHz, were analyzed in order to investigate plasma inhomogeneities in the direction of this nearby pulsar. The observations were conducted at a spacecraft distance of 330,000 km, resulting in a projected baseline of 220,000 km, providing the greatest angular resolution ever achieved at meter wavelengths. Our analysis is based on fundamental behavior of structure and coherence functions. We find that the pulsar shows scintillation on two frequency scales, both much less than the observing frequency; but modulation is less than 100%. We infer that the scattering is weak, but a refracting wedge disperses the scintillation pattern. The refraction angle of this "cosmic prism" is measured as theta_0=1.1 - 4.4 mas, with the refraction direction being approximately perpendicular to the observer vel...

  8. 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 ...

  9. 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

  10. Diseño, construcción y uso de una cámara CCD para observaciones astronómicas

    OpenAIRE

    Roca Molina, Felipe

    2014-01-01

    En este proyecto se presenta la construcción de una cámara CCD (dispositivo de carga acoplada) para su uso posterior en aplicaciones astronómicas siguiendo y adaptando las indicaciones del texto The CCD Camera Cookbook (Berry et al., 1994). Se explica el funcionamiento de una cámara CCD a nivel sencillo particularizada para el chip TC211 de la casa Texas Instuments. Se ha diseñado y construido las placas necesarias y se ha realizado un amplio estudio del funcionamiento de la...

  11. 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...

  12. 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

  13. 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.

  14. Supuestos y filiaciones filosóficas de los paradigmas astronómicos en el virreinato del Perú

    Directory of Open Access Journals (Sweden)

    Roberto Katayama Omura

    2014-03-01

    Full Text Available En el presente artículo se estudian los supuestos y filiaciones filosófico-naturales de los paradigmas astronómicos vigentes en el virreinato delPerú. Se busca demostrar que hasta el siglo XVIII fue dominante el paradigma clásico o geocéntrico en la versión moderna de Tycho Brahe y quetambién estuvo presente el paradigma clásico en su versión tradicionalo ptolemaica aunque con menos fuerza. Finalmente, se propone quedesde mediados del siglo XVIII se introduce en el virreinato peruano elparadigma moderno kepleriano-newtoniano el cual se impondrá a finesdel mismo siglo.

  15. Percepção Astronômica de Alunos do Ensino Médio da Rede Estadual de São Paulo

    Science.gov (United States)

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

    2005-08-01

    Embora a astronomia seja uma das ciências mais antigas da humanidade e muitos dos conceitos astronômicos serem populares, principalmente nesta época de alta globalização do conhecimento por intermédio de eficientes meios de comunicação e de obtenção da informação, notadamente através da internet, observa-se que uma parcela significativa dos estudantes encontra-se à margem dessas informações. O presente trabalho visa analisar o nível de conhecimento básico dos alunos de Ensino Médio da rede estadual da cidade de Suzano quanto aos fenômenos astronômicos que os rodeiam, tais como a sucessão dos dias e das estações do ano, além de questioná-los sobre fatos genéricos tais como: quais são os astros que se encontram mais próximos do planeta Terra, o que vem a ser o Sol, o Big Bang, um ano-luz, uma estrela cadente, a estrela de Bélem e o que ocasionou a extinção dos dinossauros. Para tanto foi elaborado um formulário constando de questões de múltipla escolha, o qual foi aplicado no primeiro colegial noturno da Escola Estadual Batista Renzi. Num espaço amostral de 34 alunos constatou-se que apenas 29,4% compreendiam a sucessão dos dias da semana, que apenas 20,6% explicaram corretamente as estações do ano, que apenas 20,6% tinham idéia de quais são os objetos celestes mais próximos da Terra, em contraposição 67,6% sabiam classificar corretamente o Sol como estrela, 55,9% relacionavam o Big Bang à origem do universo, apenas 20,6% identificavam um ano-luz como unidade de distância, 32,4% reconheciam uma estrela cadente como meteoro, 41,2% consideravam a estrela de Belém como um cometa e 50,0% explicaram corretamente a extinção dos dinossauros. A presente análise será expandida para as demais classes de primeiro colegial, não somente do período noturno, mas também do diurno da Escola Estadual Batista Renzi, bem como o formulário será devidamente ampliado. Já nesta primeira fase nota-se claramente o pequeno discernimento

  16. RadioAstron space VLBI imaging of polarized radio emission in the high-redshift quasar 0642+449 at 1.6 GHz

    CERN Document Server

    Lobanov, A P; Bruni, G; Kovalev, Y Y; Anderson, J; Bach, U; Kraus, A; Zensus, J A; Lisakov, M M; Sokolovsky, K V; Voytsik, P A

    2015-01-01

    Polarization of radio emission in extragalactic jets at a sub-milliarcsecond angular resolution holds important clues for understanding the structure of the magnetic field in the inner regions of the jets and in close vicinity of the supermassive black holes in the centers of active galaxies. Space VLBI observations provide a unique tool for polarimetric imaging at a sub-milliarcsecond angular resolution and studying the properties of magnetic field in active galactic nuclei on scales of less than 10^4 gravitational radii. A space VLBI observation of high-redshift quasar TXS 0642+449 (OH 471), made at a wavelength of 18 cm (frequency of 1.6 GHz) as part of the Early Science Programme (ESP) of the RadioAstron} mission, is used here to test the polarimetric performance of the orbiting Space Radio Telescope (SRT) employed by the mission, to establish a methodology for making full Stokes polarimetry with space VLBI at 1.6 GHz, and to study the polarized emission in the target object on sub-milliarcsecond scales. ...

  17. 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...

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

    Science.gov (United States)

    Popov, Mikhail V.; Bartel, Norbert; Gwinn, Carl R.; Johnson, Michael D.; Andrianov, Andrey; Fadeev, Evgeny; Joshi, Bhal Chandra; Kardashev, Nikolay; Karuppusamy, Ramesh; Kovalev, Yuri Y.; Kramer, Michael; Rudnitskiy, Alexey; Shishov, Vladimir; Smirnova, Tatiana; Soglasnov, Vladimir A.; Zensus, J. Anton

    2017-02-01

    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$0.8 mas. At longer baselines no visibility detections from the scattering disk would be expected. However, significant detections were obtained with visibility amplitudes of 3 to 5% of the maximum scattered around a mean and approximately constant up to 330,000 km. These visibilities reflect substructure from scattering in the interstellar medium and offer a new probe of ionized interstellar material. The size of the diffraction spot near Earth is 17,000$\\pm$3,000 km. With the assumption of turbulent irregularities in the plasma of the interstellar medium, we estimate that the effective scattering screen is located 0.6$\\pm$0.1 of the distance from Earth toward the pulsar.

  19. 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

  20. 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.

  1. 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

  2. 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).

  3. Tipología de recursos astronómicos históricos y fondos documentales en las cartotecas españolas: estado de la cuestión

    Directory of Open Access Journals (Sweden)

    Alonso-Lifante, M. Pilar

    2015-09-01

    Full Text Available The state of the art about a type of specialised resource with great historical and scientific value is presented: the astronomical documentation. First of all, the main types of astronomical resources are defined focusing on their historical evolution. Secondly, the result of a survey carried out between April and May 2014 about the astronomical collections in Spanish map libraries and archives is shown taking as a reference the IBERCARTO directory of 2012. Conclusions show that almost half of queried libraries and archives map have these type of documents, but disseminated in different collections. Moreover, around 70% of the institutions have catalogued all of their astronomical documentation and have used the classical encoding (MARC 21 and cataloguing standards (ISBD and ISAD(G, although recent studies have shown that these standards are not the most suitable ones to describe it. Hence, a satisfactory scientific information retrieval is not achieved.Se presenta el estado de la cuestión de un tipo de recurso especializado de gran valor histórico y científico: la documentación astronómica. Para ello, en primer lugar se definen los principales tipos de recursos astronómicos existentes señalando su evolución histórica. En segundo lugar se presentan los resultados de un estudio, realizado entre abril y mayo de 2014, sobre los fondos astronómicos existentes en cartotecas españolas, tomando como referencia el directorio de IBERCARTO de 2012. Las conclusiones indican que casi la mitad de las cartotecas encuestadas conservan documentos de este tipo, encontrándose dispersos en diferentes colecciones. Además, en torno al 70% de las instituciones tienen catalogada toda su documentación astronómica, descrita con los estándares clásicos de codificación (MARC 21 y catalogación (ISBD e ISAD(G, aunque recientes estudios han puesto de manifiesto que estos estándares no son los más adecuados para describirla, por lo que actualmente no se

  4. 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.

  5. 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

  6. 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

  7. Arqueología del cielo. Orientaciones astronómicas en edificios protohistóricos del sur de la Península Ibérica

    Directory of Open Access Journals (Sweden)

    Esteban, César

    2013-06-01

    Full Text Available We present an archaeoastronomical analysis of the orientations of six protohistoric sanctuaries and public buildings located in archaeological sites of the south of the Iberian Peninsula (Coria del Río, El Carambolo, Saltillo, Mesa de Setefilla, Tejada la Vieja and El Oral. This study, the first of its kind conducted on a sample of Early Iron Age sanctuaries in this geographic area, is based on the accurate measurement of the orientations defined by the buildings and the analysis of the horizon around them and reveals clear astronomical relations. In particular, religious buildings show similar characteristics and orientation towards an azimuth of 55°. The regularities found seem to suggest the existence of religious beliefs and rituals linked to singular positions of the brightest celestial bodies as the Sun, Moon or Venus.Presentamos un análisis arqueoastronómico de la orientación de seis santuarios y edificios de carácter público protohistóricos en sitios arqueológicos situados en el mediodía de la Península Ibérica (Coria del Río, El Carambolo, Saltillo, Mesa de Setefilla, Tejada la Vieja y El Oral. El estudio, el primero de este tipo que se realiza sobre una muestra de santuarios del Hierro Antiguo en esta área geográfica, se basa en la medida precisa de las orientaciones definidas por los edificios y el análisis del horizonte que les rodea y revela claros vínculos astronómicos. En particular, los edificios de culto muestran unas características similares y una orientación hacia un acimut de 55°. Las regularidades encontradas parecen sugerir la posible existencia de credos y rituales religiosos relacionados con posiciones singulares de los astros principales visibles a simple vista, como el Sol, la Luna o Venus.

  8. 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.

  9. Propuesta didáctica para la enseñanza de ángulos y su medida a estudiantes de grado séptimo a partir de la recreación de algunos instrumentos de posicionamiento astronómico

    OpenAIRE

    Angarita Molina, Guzmán Olmedo

    2014-01-01

    Se presenta el análisis y respuestas observadas en un instrumento de indagación, en el que se valoran las ideas previas que tienen los estudiantes de grado séptimo de educación secundaria de la Institución Educativa Distrital la Toscana-Lisboa de la localidad de Suba, con respecto al concepto de ángulo y lo que ello involucra, su definición, notación, medición, clasificación y operaciones de suma y resta, así como su relación que tiene en fenómenos astronómicos observables y medibles como por...

  10. 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.

  11. IAA : Información y actualidad astronómica (47)

    OpenAIRE

    López de Lacalle, Silbia; Vílchez Medina, José Manuel

    2015-01-01

    Felices 40.-- Un número excepcional.-- Un poco de historia.-- El universo desde Granada.-- Una supernova de libro.-- Desentrañando el enigma de los GRBs.-- Jets relativistas: viajando casi a la velocidad e la luz.-- Impactos en la Luna.-- Nebulosas planetarias recién nacidas.-- Atravesando la neblina de Titán.-- El encuentro con un cometa.-- ...

  12. IAA : Información y actualidad astronómica (32)

    OpenAIRE

    Muñoz, Olga; López de Lacalle, Silbia; García, Emilio José; Masegosa, Josefa; Alberdi, Antxón; González, Marta; Martín-Ruiz, Susana; Villar-Martin, Montse; Emilio J. Alfaro

    2010-01-01

    Sumario : El laboratorio de polvo cósmico del IAA ...2 La interminable historia del agua en la Luna ...6 Multiversos y cómics ...9 HISTORIAS DE ASTRONOMÍA. Caroline Herschel ...13 DECONSTRUCCIÓN Y otros ENSAYOS. Zoom al centro galáctico ...14 EL “MOBY DICK” DE... Marta González (IAA-CSIC)...16 ACTUALIDAD ...17 ENTRE BASTIDORES ...21 CIENCIA: PILARES E INCERTIDUMBRES Tormentas solares ...22 ACTIVIDADES IAA, AGENDA Y RECOMENDADOS ...23 y 24

  13. IAA : Información y actualidad astronómica (23)

    OpenAIRE

    2007-01-01

    Sumario : La capa de ozono : indicios de recuperación ...3 Mujeres en astronomía ...7 Activas y perezosas : las galaxias también lo son ...11 DECONSTRUCCIÓN Y otros ENSAYOS Las factorías de supernovas ...14 ACTUALIDAD ...16 ENTRE BASTIDORES ...20 HISTORIAS DE ASTRONOMÍA Púlsares ...21 CIENCIA: PILARES E INCERTIDUMBRES Cometas ...22 ACTIVIDADES IA...

  14. IAA : Información y actualidad astronómica (16)

    OpenAIRE

    2005-01-01

    Sumario : Einstein, una estrella...¿binaria?. ...4 Cuásares y chorros relativistas....6 Lentes gravitatorias...9 Ondas gravitatorias: dinámica del espacio-tiempo...10 La irresistible tentación cosmológica de la Relatividad General...12 Más allá de la relatividad...15 Mecánica cuántica y gravitación...16

  15. 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.

  16. IAA : Información y actualidad astronómica (49)

    OpenAIRE

    2016-01-01

    Sumario : El método Doppler y la estrella Próxima Centauri...3 Las estrellas ¡laten!...5 Dinámica de los sistemas planetarios...7 FRBs: fuentes transitorias sin un origen claro...9 DECONSTRUCCIÓN Y otros ENSAYOS. El proyecto CALIFA ...12 CIENCIA EN HISTORIAS...Maria Assumpció Catalá i Poch... 14 EL “MOBY DICK” DE... Emilio J. Alfaro (IAA)...15 ACTUALIDAD ...16 ENTRE BASTIDORES...Brexit, ¿ejemplo de incultura científica? ...21 SALA LIMPIA ...22 CIENCIA: PILARES E ...

  17. 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

  18. 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).

  19. 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.

  20. 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.

  1. 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.

  2. Erratum: Generalized quantum state sharing of the arbitrary two particles state [Sci China Phys Mech Astron, 2010, 53(11): 2064

    Institute of Scientific and Technical Information of China (English)

    WANG Chuan

    2011-01-01

    Eqs.(3)-(6)should read[1]:|φ+m>=M(|00>=+1/m*|11>),(1)|φ-m>=M(1/m|00>-|11>),(2)|φ-m>=M(|01>=+1/m*|10>),(3)|φ-m>=M(1/m|01>-|10>),(4)whereM=|m|/√1+|m|2.Provided that one can prove eq.(8)which describes the state of the composite system,it should read |∧>sub=C1(α|0000>+nβ/m|0101>+nγ/m|1010>+n2δ/m2|1111>)b1b2c1c2,(5)whereC1=1/√|α|2+|nβ/m|2+|nγ/m|2+|n2δ/m2|2is the normalized factor.Here we give the fidelity of a pure state and the density matrix of the state described by eq.(11)should read:F=||α|2+|β|2n/m+|γ|2n/m+|δ|2n2/m2| /|α|2+|βn/m|2+|γn/m|2+|δn2/m2|2.If the quantum channels are composed of generalized Bell states,the state sharing process can be realized by generalized GHZ state measurement.

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

    OpenAIRE

    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...

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

    OpenAIRE

    2016-01-01

    [Resumen] En la llamada era de las TIC, las capacidades de los sistemas de adquisición de datos han aumentado enormemente, de forma que resulta complicado almacenar toda la información que producen, así como su análisis posterior. Esta explosión de datos ha aparecido recientemente en el campo de la Astronomía, donde cada vez se observan un número mayor de objetos, con mayor periodicidad. Un ejemplo de esto es la próxima misión Gaia, que observará múltiples propiedades de hasta ...

  5. 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.

  6. Impacto de variaciones climáticas de origen astronómico en las condiciones ambientales de medios marinos profundos a partir del análisis geoquímico en el eoceno de Sopelana (Bizkaia)

    OpenAIRE

    Martínez Braceras, Naroa

    2014-01-01

    RESUMEN La cicloestratigrafía es la especialidad geológica que se ocupa de ciclos repetitivos y de duración constate en sucesiones geológicas continuas. Estos ciclos están estrechamente relacionados con cambios climáticos periódicos inducidos por las variaciones en los parámetros orbitales terrestres, dentro de los que destacan los llamados Ciclos de Milankovitch. La sucesión eocena estudiada en Sopelana (Bizkaia) está caracterizada por la alternancia de margas y calizas (hemi)pelágicas...

  7. Análisis, estudio y conservación de los edificios astronómicos mayas. Arquitectura maya y urbanismo, una aproximación desde la astronomía y el paisaje.

    OpenAIRE

    MAY CASTILLO, MANUEL

    2016-01-01

    El presente trabajo representa el resultado final de seis años de investigación en la región maya y versa sobre las relaciones entre la arquitectura y el urbanismo con el paisaje y la astronomía. En una primera parte se presentan los fundamentos metódicos para el estudio de la arquitectura y el urbanismo maya, a partir de la lectura de los datos del paisaje circundante y las orientaciones arquitectónicas. A lo anterior se le suman los datos provistos por las fuentes pr...

  8. 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.

  9. 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.

  10. 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

  11. 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.

  12. 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

  13. Spectra: Time series power spectrum calculator

    Science.gov (United States)

    Gallardo, Tabaré

    2017-01-01

    Spectra calculates the power spectrum of a time series equally spaced or not based on the Spectral Correlation Coefficient (Ferraz-Mello 1981, Astron. Journal 86 (4), 619). It is very efficient for detection of low frequencies.

  14. 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.

  15. REVISTA MEXICANA DE ASTRONOMÍA Y ASTROFÍSICA, A REAL OPTION FOR ASTRONOMICAL PUBLICATION

    Directory of Open Access Journals (Sweden)

    S. Torres-Peimbert

    2011-01-01

    Full Text Available Presentamos datos estadísticos sobre la Revista Mexicana de Astronomía y Astrofísica. Consideramos que esta publicación está bien posicionada en la literatura astronómica internacional. Igualmente, presentamos información sobre la Serie de Conferencias, que ha tenido muy amplia aceptación en la comunidad astronómica.

  16. REVISTA MEXICANA DE ASTRONOMÍA Y ASTROFÍSICA, A REAL OPTION FOR ASTRONOMICAL PUBLICATION

    OpenAIRE

    2011-01-01

    Presentamos datos estadísticos sobre la Revista Mexicana de Astronomía y Astrofísica. Consideramos que esta publicación está bien posicionada en la literatura astronómica internacional. Igualmente, presentamos información sobre la Serie de Conferencias, que ha tenido muy amplia aceptación en la comunidad astronómica.

  17. Usability of Light-Emitting Diodes in Precision Approach Path Indicator Systems by Individuals With Marginal Color Vision

    Science.gov (United States)

    2014-05-01

    Products , Inc., Albuquerque, NM) equipped with a Verilux full spectrum (F15T8/VLX) lamp. The participants recorded their responses for each trial...by ATS Aerospace, Inc., Saint-Bruno, QC) and the older model, Crouse-Hinds Type W-1, which is no longer in production . This study will only present...possible. REFERENCES Astronics DME Corporation (2014). PAPI: Precision ap- proach path indictor. http://www.astronics.com/_images/ airfield-lighting

  18. 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.

  19. 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 ...

  20. Off-axis point spread function and efficiency for adaptive optics at San Pedro Mártir and other sites

    Directory of Open Access Journals (Sweden)

    V. G. Orlov

    2003-01-01

    Full Text Available Estimamos la e ciencia de correci on para sistemas astron omicos de optica adaptativa fuera de eje a partir de cuatro per les de C2 n obtenidos en cuatro sitios astron omicos: Observatorio Europeo Austral en Paranal, Chile; Observatorio de Roque de los Muchachos, Islas Canarias, Observatorio Astron omico Nacional en San Pedro M artir, M exico y Observatorio de Haute Provence, Francia. Esta e ciencia se calcula a trav es del cociente de Strehl de la imagen corregida en las bandas V, J y K y para telescopios de la clase de 8-m. Tambi en realizamos un an alisis detallado de la anisotrop a de la funci on de distribuci on de punto en posiciones fuera del eje de correcci on de sistemas de optica adaptativa para el caso del sitio de San Pedro M artir. Los per les de C2 n usados en este trabajo fueron obtenidos con globos instrumentados y con un Scidar Generalizado.

  1. 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

  2. CONTINUOUS MONITORING USING BOOTES WORLDWIDE NETWORK

    Directory of Open Access Journals (Sweden)

    David Hiriart

    2014-01-01

    Full Text Available Se presentan los avances en la instalaci ́on del quinto teles copio de la red mundial de telescopios rob ́oticos BOOTES. Este telescopio, denominado BOOTES–5, se instalar ́a en el Observatorio Astron ́omico Nacional en la sierra San Pedro M ́artir, en Baja California, M ́exico. La operaci ́on coordinada de este telescopio con los de la red BOOTES operando en China y Espa ̃na permitir ́a un monit oreo continuo de fuentes astron ́omicas.

  3. 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).

  4. VIMOS Integral Field Spectroscopy of Gaseous Nebulae in Local Group Dwarf Galaxies

    Science.gov (United States)

    Held, E. V.; Gullieuszik, M.; Saviane, I.; Sabbadin, F.; Momany, Y.; Rizzi, L.; Bresolin, F.

    The study of very metal-poor dwarf irregular (dIrr) galaxies is fundamental to test the cosmological scenarios of galaxy formation. Among Local Group galaxies, Leo A and SagDIG are probably the most metal-poor dwarfs, as suggested by estimates of their nebular abundances based on the empirical method [I. Saviane, L. Rizzi, E.V. Held, F. Bresolin, Y. Momany in Astron. Astrophys. 390, 59 (2002); E.D. Skillman, R. Terlevich, J. Melnick in Mon. Not. R. Astron. Soc. 240, 563 (1989); L. van Zee, E.D. Skillman, M.P. Haynes in Astrophys. J. 637, 269 (2006)].

  5. Acto de inauguración del XVIII Congreso Bianual de Geofísicos y Geodestas en la UNLP

    OpenAIRE

    Forte, Juan Carlos; Lima, Luis Julián; Torge, Wolfgang; Rodríguez, Rubén

    1994-01-01

    Radio Universidad Nacional de La Plata transmite en directo el acto de inauguración del XVIII Congreso Bianual de Geofísicos y Geodestas, realizado en 1994 en la UNLP. Hablan el decano de la Facultad de Ciencias Astronómicas y Geofísicas, Juan Carlos Forte, sobre el origen e historia del Observatorio Astronómico de La Plata; el titular de la Asociación Argentina de Geofísica y Geodesia, ingeniero Rubén Rodríguez; el presidente de la Asociación Internacional de Geofísica, profesor Wolfgang Tor...

  6. 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.

  7. Integrated spectral study of reddened globular clusters and candidates

    Science.gov (United States)

    Bica, E.; Claria, J. J.; Piatti, A. E.; Bonatto, C.

    1998-09-01

    This paper presents integrated spectra in the range 6700 - 9500 Angstroms for 20 Galactic globular clusters (and candidates) in the bulge and 5 others projected on the Galactic disk (|l|>30mbox {^{\\circ}}\\ and |b|Complejo Astronómico El Leoncito (CASLEO), Argentina, and European Southern Observatory (ESO), Chile.

  8. ATCA radio detection of GX 339-4 in the rising hard state

    Science.gov (United States)

    Miller-Jones, James C. A.; Sivakoff, Gregory R.; Maccarone, Tom J.; Deller, Adam T.; Jonker, Peter; Nelemans, Gijs; Tzioumis, Tasso; Altamirano, Diego; Pawar, Devraj; Russell, Dave

    2013-08-01

    ATCA radio detection of GX 339-4 in the rising hard state James C.A. Miller-Jones (ICRAR - Curtin), Gregory R. Sivakoff (U. Alberta), Tom J. Maccarone (TTU), Adam T. Deller (ASTRON), Peter Jonker (SRON), Gijs Nelemans (U Nijmegen), Tasso Tzioumis (CSIRO), Diego Altamirano (U Amsterdam), Devraj Pawar (U. Mumbai), Dave Russell (IAC, Tenerife)

  9. The Circumnuclear Material in the Galactic Centre : A Clue to the Accretion Process

    NARCIS (Netherlands)

    Sanders, R. H.

    1997-01-01

    Submitted to: Mon. Not. R. Astron. Soc. Abstract: On the basis of ``sticky particle'' calculations, it is argued that the gas features observed within 10 pc of the Galactic Centre-- the circumnuclear disk (CND) and the ionized gas filaments-- as well as the newly formed stars in the inner one parsec

  10. 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...

  11. Star formation and the interstellar medium in low surface brightness galaxies; 1, Oxygen abundances and abundance gradients in low surface brightness disk galaxies

    NARCIS (Netherlands)

    Blok, W. J. G. de; Hulst, J. M. van der

    1998-01-01

    Submitted to: Astron. Astrophys. Abstract: We present measurements of the oxygen abundances in 64 HII regions in 12 LSB galaxies. We find that oxygen abundances are low. No regions with solar abundance have been found, and most have oxygen abundances $sim 0.5$ to 0.1 solar. The oxygen abundance appe

  12. 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

  13. A Hipparcos census of the nearby OB associations

    NARCIS (Netherlands)

    Zeeuw, P. T.; Hoogerwerf, R. D; Bruijne, J. H. J. de; Brown, A. G. A.; Blaauw, A.

    1999-01-01

    Published in: Astron. J. 117 (1999) 354 citations recorded in [Science Citation Index] Abstract: A comprehensive census of the stellar content of the nearby OB associations is presented, based on Hipparcos positions, proper motions, and parallaxes. Moving groups are identified by combining de Bruijn

  14. Local Pulsars; A note on the Birth-Velocity Distribution

    NARCIS (Netherlands)

    Blaauw, A.; Ramachandran, R.

    1998-01-01

    Submitted to: Astron. Astrophys. Abstract: We explore a simple model for the representation of the observed distributions of the motions, and the characteristic ages of the local population of pulsars. The principal difference from earlier models is the introduction of a unique value, S, for the kic

  15. 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

  16. Report on Research

    Science.gov (United States)

    1989-06-01

    Coronal Mass Ejections? Am. Astron. Soc. Mtg., Kansas City MO (5-9 BROADFOOT, A.L., SANDEL , B.R. (Univ. of June 1988) Arizona, Tuscon, AZ); and Knecht...Engineering, Lexington, MA); MORRIS, Daytime and Nighttime F Layer Troughs R.A., PAULSON, J.F. (AFGL); and 1988 Cambridge Wkshp. on Polar Cap MICHELS

  17. Civilización y cultura

    Directory of Open Access Journals (Sweden)

    Luis López de Mesa

    1958-10-01

    Full Text Available Discurso pronunciado el 20 de agosto último en el salón de actos de la Biblioteca Luis Ángel Arango, durante la sesión conjunta celebrada por las Academias Colombianas de Historia y Ciencias Naturales para conmemorar el aniversario de la fundación del Observatorio Astronómico Nacional.

  18. Characterization of the near-Earth Asteroid 2002 NY40

    Science.gov (United States)

    2007-09-01

    and Vesta ; Rotational Poles and Triaxial Ellipsoid Dimensions, Icarus, 132, 80-99 – 17 – Fish, D.A., Brinicombe, A.M., & Pike, E.R. 1995, Blind...rectification of observed sistributions, Astron. J. 79, 745-754 McCarthy, D.W., Freeman, J.D., Drummond, J.D 1994, High Resolution Images of Vesta at

  19. A Study of the Sensitivity of the Greenland Sea Acoustic Tomography

    Science.gov (United States)

    1989-12-01

    Bushong , 1987), and surface waves (Lynch et al, 1987). In the future, monitoring of large-scale ocean dyramics on a global basis may be achieved using...34Numerical Applications of a Formalism for Geophysical Inverse Problems", Geophys. J. R. Astron. Soc., Vol. 13, pp. 247-76, 1967. Bushong , P.J., "Tomographic

  20. 77 FR 28668 - Technical Standard Order (TSO)-C91a, Emergency Locator Transmitters (ELTs)

    Science.gov (United States)

    2012-05-15

    ... the cancelled TSO will result in no new TSO-C91a design or production approvals being issued... no plans to revise 14 CFR 91.207. The second commenter, Astronics DME Corporation, provided two... organizations requested the FAA reiterate that cancelation of TSO-C91a does not impact the continued...

  1. Evaluation of the Tri-Service Laboratory System. Volume 1. Overview and Executive Summary.

    Science.gov (United States)

    1983-06-20

    Oakland had the SMAC (high-volume chemistry analyzer ), Coulter S+ (high volume * -instrument used in hematology) and Clintech instruments on-line. Wright...Patterson had only the Hycel (high-volume chemistry analyzer ) on-line. Eisenhower had the SMAC, ABA 200, Clintech, Beckman Astron, and Coulter S

  2. Information for Authors

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Science in China Series G-Physics, Mechanics & Astronomy (Sci China Ser G-Phys Mech Astron) is a monthly peer-reviewed academic journal supervised by the Chinese Academy of Sciences,and co-sponsored by the Chinese Academy of Sciences

  3. Performance characteristics of modern self-expanding nitinol stents indicated for SFA

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, W.; Behrens, P. [Rostock Univ. (Germany). Inst. fuer Biomedizinische Technik; Wissgott, C.; Andresen, R. [Westkuestenklinikum Heide - Akademisches Lehrkrankenhaus der Universitaeten Kiel, Luebeck und Hamburg (Germany). Inst. fuer Diagnostische und Interventionelle Radiologie; Schmitz, K.P. [Institut fuer ImplantatTechnologie und Biomaterialien e.V., Rostock-Warnemuende (Germany); Rostock Univ. (Germany). Inst. fuer Biomedizinische Technik

    2011-09-15

    Purpose: To evaluate performance characteristics of currently available superficial femoral artery (SFA) stents and stent delivery systems (SDS). Materials and Methods: Six 7 mm/80 mm stent systems were included: BIOTRONIK Astron Pulsar (4F), EDWARDS LifeStent Flexstar, ev3 PROTEGE Everflex, CORDIS Smart Control, BARD E-Luminexx, GUIDANT Absolute (all 6F). The SDS were evaluated for profile, flexibility in the stent region, trackability and pushability through a tortuous vessel model and release force during deployment. The stents were evaluated for flexibility, radial force during expansion and compression, and shortening. Results: The 4F system had a profile of 1.45 mm, and the 6F stent systems had a profile of 1.96 - 2.10 mm. The Astron Pulsar was most flexible (195 Nmm{sup 2}) compared to 334 - 972 Nmm{sup 2} for the 6F systems. The track force of the stiffest system (Flexstar, 0.314N) was higher than that of the Astron Pulsar (0.273N) but lower than that of the other systems (0.387 - 0.579N). The release force was 1.69N (Absolute), 2.05N (Astron Pulsar) up to 13.00N (Flexstar). The radial force for a 6 mm stent diameter during expansion ranged from 3.95N (Absolute) and 3.99N (Astron Pulsar) up to 7.22N (FlexStar) but was higher when compressed. Conclusion: The 4F system had the best flexibility and trackability. The release force was high in most systems with release handles. The radial force of all tested stents covers a broad range. These results could be helpful to find the best stent for different lesions. (orig.)

  4. 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

  5. Influence of the Tachocline on Solar Evolution

    CERN Document Server

    Brun, A S

    2000-01-01

    Recently helioseismic observations have revealed the presence of a shear layer at the base of the convective zone related to the transition from differential rotation in the convection zone to almost uniform rotation in the radiative interior, the tachocline. At present, this layer extends only over a few percent of the solar radius and no definitive explanations have been given for this thiness. Following Spiegel and Zahn (1992, Astron. Astrophys.), who invoke anisotropic turbulence to stop the spread of the tachocline deeper in the radiative zone as the Sun evolves, we give some justifications for their hypothesis by taking into account recent results on rotating shear instability (Richard and Zahn 1999, Astron. Astrophys.). We study the impact of the macroscopic motions present in this layer on the Sun's structure and evolution by introducing a macroscopic diffusivity $D_T$ in updated solar models. We find that a time dependent treatment of the tachocline significantly improves the agreement between comput...

  6. 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

  7. Reconnaissance field report for the search of large telescope sites in the sierra San Pedro Mártir, Baja California, México

    Directory of Open Access Journals (Sweden)

    Erika Sohn

    2007-01-01

    Full Text Available La Sierra San Pedro Mártir en el estado de Baja California, México, es conocida por sus excelentes condiciones para la observación astronómica. Ofrece una serie de sitios con elevaciones que rebasan los 2650 m, potencialmente apropiados para la instalación de futuros grandes telescopios. Algunos de estos sitios son remotos y es necesario determinar sus rutas de acceso para efectuar mediciones de evaluación de las condiciones para la observación astronómica. Durante el verano de 2005 se visitaron seis sitios que pueden ser adecuados para la instalación de telescopios e instrumentos de medición de la calidad del cielo, para determinar sus coordenadas asÍ como sus posibles rutas de acceso. En este trabajo se presenta una breve descripción de cada uno de estos sitios

  8. La variación temporal de las constantes fundamentales

    Science.gov (United States)

    Bersten, M.; Landau, S.; Vucetich, H.

    Las diferentes teorías que unifican las cuatro interacciones fundamentales coinciden en predecir variaciones temporales y espaciales de las constantes fundamentales pero difieren en la forma de esta variación. Las observaciones astronómicas y geofísicas permiten establecer cotas sobre la variación de dichas constantes. ésto nos proporciona una herramienta importante para testear las diferentes teorías. En particular, se utilizó el modelo de supercuerdas propuesto por Damour y Polyakov. Se obtuvieron límites sobre los parámetros libres de dicho modelo consistentes con un conjunto de datos astronómicos y geofísicos.

  9. 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.

  10. U.S. Naval Observatory Annual Report 2001-2002

    Science.gov (United States)

    2002-06-01

    Miknaitis, G., Munn, J. A., Nichol, R., Oka- mura, S., Pier, J. A., Prada , F., Richards, G. T., Szalay, A., and York, D. G. ~2001!. ‘‘A Survey of z...Implications for Dark Bursts,’’ Astron. Astrophys. 369, 373. Garcia -Melendo, E., Henden, A. A., and Gomez-Forrelad, J. M. ~2001!. ‘‘GSC 5002-0629: A

  11. Earthquake Characteristics and Earthquake-Explosion Discrimination

    Science.gov (United States)

    1977-11-30

    asymtotic solutions of ordinary linear differential equations to the second order with special reference to a turning point. Trans. Am. Math. Soc. 67...Astron. Soc. 8, 44-63. 79b Wasow, W. (1965). Asymptotic expansions for ordinary differential equations , Vol. 14, Pure and Applied Mathematics...frequency dependence. Equation (3.4) demonstrates explicitly the nonuniqueness inherent in determining R(w) when t is not known. Unfortunately, since t

  12. 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.

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

    OpenAIRE

    Groot, P. J. (Paul J.); Kuijken, K.; 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 ...

  14. 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).

  15. The 1859 Space Weather Event: Then and Now

    Science.gov (United States)

    2006-01-01

    region indicates the approximate city limits of London circa 1859. The star on the Basic questions raised about the nature of the promi- Thames river...Zhang et al., 2001; Cliver and Hudson , 2002) and Siscoe for organizing a timely, stimulating, and produc- the nature of underlying "magnetic disease...solar flares associated with coronal mass Res. 101, 15533-15546, 1996. ejection. Astron. Astrophys. 304, 585-594, 1995. Cliver, E.W., Hudson , H.S

  16. Semi-holographic model including the radiation component

    CERN Document Server

    del Campo, Sergio; Magaña, Juan; Villanueva, J R

    2014-01-01

    In this letter we study the semi holographic model which corresponds to the radiative version of the model proposed by Zhang et al. (Phys. Lett. B 694 (2010), 177) and revisited by C\\'ardenas et al. (Mon. Not. Roy. Astron. Soc. 438 (2014), 3603). This inclusion makes the model more realistic, so allows us to test it with current observational data and then answer if the inconsistency reported by C\\'ardenas et al. is relaxed.

  17. Construcción de un algoritmo en paralelo para la transformada rápida de fourier

    OpenAIRE

    Higuera, Mario; Sarria, Humberto; Fonseca, Diana; Idarraga, Jhon

    2013-01-01

    Presentamos un código para el cálculo en paralelo de la Transformada Rápida de Fourier (FFT), sobre un cluster de 2n computadores. El código ha sido utilizado para obtener la transformada de una imagen astronómica, a la cual se le aplicó un filtro, para eliminar cierto tipo de frecuencias. Luego, se recupera una imagen filtrada, haciendo uso de la transformada inversa de Fourier.

  18. 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).

  19. 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.

  20. Follow up spectroscopy and photometry of TYC 2505-672-1 (MASTER OT J095310.04+335352.8)

    Science.gov (United States)

    Afanasiev, V.; Denisenko, D.; Krushinsky, V.; Gorbovskoy, E.; Lipunov, V.; Balanutsa, P.; Yecheistov, V.; Tiurina, N.; Kornilov, V.; Belinski, A.; Shatskiy, N.; Chazov, V.; Kuznetsov, A.; Zimnukhov, D.; Zalozhnih, I.; Popov, A.; Bourdanov, A.; Punanova, A.; Ivanov, K.; Yazev, S.; Budnev, N.; Konstantinov, E.; Chuvalaev, O.; Poleshchuk, V.; Gress, O.; Parkhomenko, A.; Tlatov, A.; Dormidontov, D.; Senik, V.; Yurkov, V.; Sergienko, Y.; Varda, D.; Sinyakov, E.; Shurpakov, S.; Shumkov, V.; Podvorotny, P.; Levato, H.; Saffe, C.; Mallamaci, C.; Lopez, C.; Podest, F.

    2013-02-01

    Following the detection of TYC 2505-672-1 fading episode by MASTER network (Denisenko et al., ATel #4784) we have performed the additional spectroscopic and photometric observations of this object in minimum light. The spectrum of TYC 2505-672-1 was obtained with the Russian 6-m BTA telescope (SAO RAS, Nizhniy Arkhyz, Karachay-Cherkessia) + SCORPIO instrument (Afanasiev and Moiseev, 2005, Astron. Lett., Vol.

  1. LISA-The Library and Information Services in Astronomy Conferences

    Science.gov (United States)

    2007-01-01

    WorldCat shows that 107 libraries have copies of these proceedings. Much credit must be given overall to Gart Westerhout, for without his support...the comparatively small number of core journals and databases , coupled with generous funding from space agencies and non-profit organizations, astron...appeared in July 1995. More recent LISA meetings discussed net- worked databases , digitization projects, open access projects in astronomy libraries, digital

  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. Observando los efectos de la Relatividad General alrededor de los agujeros negros

    OpenAIRE

    Barcons, Xavier

    2015-01-01

    Observaciones astronómicas de la materia que rodea los agujeros negros ponen en evidencia algunas predicciones de la Relatividad General en condiciones de campo gravitatorio fuerte. Una de ellas, el redshift gravitatorio, no solo se observa de forma rutinaria sino que se usa para medir la rotación del agujero negro. El spin de los agujeros negros gigantes encierra la clave de su crecimiento, e indirectamente de la evolución de las galaxias.

  4. When the Future Becomes the Past: Where will our Print Collection Be in 2050?

    Science.gov (United States)

    2015-04-01

    Library and Information Services in Astronomy VII: Open Science at the Frontiers of Librarianship ASP Conference Series, Vol. 492 A. Holl, S...John Huchra gave the keynote address and spoke about the future of science libraries in the information age. He listed five things libraries needed to...have about 80,000 astron- omy books and journals . The US Naval Observatory library was started in 1843 when the founder was given a ticket to Europe and

  5. 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.

  6. 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.

  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. HST Observations of Saturnian Satellites during the 1995 Ring Plane Crossings

    Science.gov (United States)

    McGhee, Colleen A.; Nicholson, Philip D.; French, Richard G.; Hall, Katherine J.

    2001-08-01

    In May, August, and November 1995, Hubble Space Telescope (HST) observations during Saturn's ring-plane crossings allowed us to view saturnian satellites normally hidden to Earth-based observers in the glare of the rings. New measurements of Janus, Epimetheus, Prometheus, and Pandora have been combined to form revised orbital solutions using all three HST data sets. These measurements and orbit fits are presented, as well as similar fits for the brighter satellites Mimas, Tethys, Enceladus, Dione, and Rhea. Observations of the Lagrangian satellites Telesto, Calypso, and Helene are also reported. While most satellites were found to be close to their expected positions based on previous orbital solutions (Nicholson et al. 1992, Icarus100, 464-484; Jacobson 1996, Bull. Amer. Astron. Soc.28, 1185; and Harper and Taylor 1993, Astron. Astrophys. 268, 326-349). Prometheus lagged behind its predicted longitude by 18.85°±0.04°. A systematic drift in Pandora's longitude of -1.85° relative to the Voyager ephemeris was observed between May and November. The new data on the coorbital satellites Janus and Epimetheus have resulted in a revised mass for Janus, ˜6% smaller than the previous value (Jacobson 1995, Bull. Amer. Astron. Soc.27, 1202). Subtraction of light from the edge-on rings has led to additional detections of objects S/1995-S1 and S3 (Bosh and Rivkin 1995, Science272, 518-521) in the May data, and S/1995-S5, S6, S7 (Nicholson et al. 1995, Bull. Amer. Astron. Soc. 27, 1202) and S/1995-S9 (Roddier et al. 1996) in the August images. S1 is identified with Atlas but leads its predicted position by ˜25°. S3 has an orbit consistent with that of the narrow F ring, but S5, S6, S7, and S9 now appear to orbit ˜530-950 km interior to this ring. S7 and S9 may even be coorbital with Prometheus. An object in the May images, possibly corresponding to S7, is also found to lie very close to Prometheus' orbit (˜800 km interior to the F ring), but no convincing detections of

  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. Segundo Catálogo Estelar del Hemisferio Sur con Astrolabio Fotoeléctrico PAII

    Science.gov (United States)

    Manrique, W. T.; Podestá, R. C.; Alonso, E.; Actis, E. V.; Pacheco, A. M.; Bustos, G.; Lizhi, L.; Zezhi, W.; Fanmiao, Z.; Hongqi, W.; Perdomo, R.

    Recordamos que entre el Observatorio Astronómico ``Félix Aguilar'', el Observatorio Astronómico de Beijing y el Observatorio Astronómico de La Plata, se ha convenido en desarrollar un Proyecto de Investigación conjunto, para la observación sistemática de estrellas en el Hemisferio Sur, con el objeto de la elaboración de un Catálogo Estelar Global utilizando un Astrolabio Fotoeléctrico PAII del Observatorio de Beijing, que ha sido usado con éxito en la República de China. En este trabajo se presenta el Segundo Catálogo Estelar del Hemisferio Sur, derivado de las observaciones realizadas con el PAII instalado en el OAFA, durante el períiodo Febrero de 1992 a Marzo de 1997. En este lapso se han observado mas de 400000 pasajes estelares, obteniéndose las correcciones Δ α y Δ δ de 5241 estrellas del FK4, FK5, FK5 Ext., SRS, CAMC y GC. Las precisiones medias son del orden de ± 3,2 ms en ascensión recta y ±0."057 en declinación. Rango de magnitudes : 2,0 a 11,5 Rango de declinaciones : -3o a -60o Epoca Media : 1994.9 Se analizan los residuos en función de la magnitud y tipo espectral, correcciones de grupo y frecuencia de distribución Δ α y Δ δ.

  12. Opto-mechanical design for transmission optics in cryogenic IR instrumentation

    Science.gov (United States)

    Kroes, Gabby; Kragt, Jan, II; Navarro, Ramon; Elswijk, Eddy; Hanenburg, Hiddo

    2008-07-01

    ASTRON is involved in the development and realization of various optical astronomical instruments for ground-based as well as space telescopes, with a focus on near- and mid-infrared instrumentation. ASTRON has developed, among others, cryogenic optics for the first generation ESO VLT and VLTI instruments VISIR, MIDI and the SPIFFI 2K-camera for SINFONI. Currently under construction are MIRI for the James Webb Space Telescope and X-shooter for the second generation ESO VLT instrumentation, while the initial design of several ELT instruments has started. Mounting optics is always a compromise between firmly fixing the optics and preventing stresses within the optics. The fixing should ensure mechanical stability and thus accurate positioning in various gravity orientations, temperature ranges, during launch, transport or earthquake. On the other hand, the fixings can induce deformations and sometimes birefringence in the optics and thus cause optical errors. Even cracking or breaking of the optics is a risk, especially at the cryogenic temperatures required in instruments for infrared astronomy, where differential expansion of various materials amounts easily to several millimetres per meter. Special kinematic mounts are therefore needed to ensure both accurate positioning and low stress. Though ASTRON is involved in the full realization of instruments from initial design to commissioning, this paper concentrates on the opto-mechanical design of optics mountings, especially for large transmission optics in cryogenic circumstances. It describes the development of temperature-invariant ("a-thermal"), kinematic designs and how they are implemented in instruments such as SPIFFI and X-shooter.

  13. Generación de una malla de ondulaciones geoidales por el método GPS/nivelación y redes neuronales artificiales a partir de datos dispersos

    OpenAIRE

    Carrión Sánchez, José Luis

    2013-01-01

    En este trabajo se presenta un método de interpolación basado en el entrenamiento de una Red Neuronal Artificial del tipo Multicapa (RNAM) con datos obtenidos en un área del Ecuador Continental, con el objetivo de obtener valores de ondulación geoidal. Los resultados obtenidos mediante la interpolación con la RNAM presentan errores menores a 15 centímetros. Facultad de Ciencias Astronómicas y Geofísicas

  14. Cámara CCD Directa con el Telescopio de 2.15 m del CASLEO: algunos diagnósticos

    Science.gov (United States)

    Cellone, S. A.

    Se efectuaron algunas pruebas con la cámara CCD (+ Reductor Focal) instalada en el foco Cassegrain del Telescopio de 2.15 m del Complejo Astronómico El Leoncito (CASLEO). Las conclusiones más significativas son: Los tiempos de exposición efectivos difieren de los nominales en una fracción apreciable de segundo. En exposiciones de menos de 3 segundos, la iluminación no es pareja en todo el detector. En consecuencia, se recomiendan los pasos a seguir por los astrónomos tanto durante la observación como en la reducción de sus datos.

  15. 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.

  16. 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

  17. 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

  18. La gravedad en Bruno, Kleper y Newton. la distribución de la materia y sus implicaciones cosmológicas

    OpenAIRE

    M. Diego Pintado

    2016-01-01

    En este trabajo se describe en modo sucinto el papel fundamental y determinante del problema de la gravitación universal en la historia de la cosmología moderna, indagándose así mismo los factores que le dieron origen, principalmente la proposición de la formulación de la ley de gravedad, sus antecedentes, y a su vez se repasan los problemas astrofísicos, astronómicos y filosóficos de este nuevo esquema cosmológico. El esquema de esta monografía traza un breve examen epistemológico, luego un ...

  19. 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.)

  20. Procesos para una Astronomía que le aporte a Colombia

    OpenAIRE

    Duque Escobar, Gonzalo

    2011-01-01

    Se ha validado el Plan Nacional de Desarrollo Tecnológico en Astronomía 2011-2030, para el Plan Estratégico 2009-2012 de la Comisión Colombiana del Espacio CCE, por el Grupo de Astronáutica, Astronomía y Medicina Aeroespacial. Esperamos que el grupo de astrónomos convocado, responsable de la investigación centrado en procesos científicos existentes y no en distractores, pueda señalar las acciones pertinentes e identificar los recursos necesarios, para hacer viable un desarrollo científico y t...

  1. A Search for Giant Planet Companions to T Tauri Stars

    Science.gov (United States)

    2012-12-20

    Teff, log g, and metallicity of our targets. We then used SYNTHMAG ( Piskunov 1999) to create template spectra from the NextGen models along with input...Ireland, M. J. 2012, ApJ, 745, 5 Kupka, F. G., Ryabchikova, T. A., Piskunov , N. E., Stempels, H. C., & Weiss, W. W. 2000, Balt. Astron., 9, 590 Lafrenière...Paulson, D. B., & Yelda, S. 2006, PASP, 118, 706 Percy, J. R., Gryc, W. K., Wong, J. C.-Y., & Herbst, W. 2006, PASP, 118, 1390 Piskunov , N. 1999, in

  2. Teoría de perturbaciones cosmológicas en teorías de gravedad modificada f(R)

    OpenAIRE

    2015-01-01

    Recientes observaciones astronómicas de supernovas (SNIa) y Oscilaciones Bariónicas Acústicas (por sus siglas en ingles) (BAO) indican que el Universo se encuentra en una etapa de expansión acelerada. En el marco de la Relatividad General (RG), esta expansión es explicada por una constante cosmológica positiva o modelos de materia exótica conocida en la literatura como energía oscura. Sin embargo, hay una alternativa para explicar esta expansión acelerada sin modelos de m...

  3. 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.

  4. Joseph Marius Alexis Aubin, Memorias sobre la pintura didáctica y la escritura figurativa de los antiguos mexicanos, edición e introducción de Patrice Giasson, traducción de Francisco Zaballa y Patrice Giasson, presentación de Miguel León Portilla,

    OpenAIRE

    Russo, Alessandra

    2005-01-01

    La historia de uno de los mayores acervos de códices mexicanos prehispánicos y coloniales hoy conservados -el que forma lo esencial del Fondo mexicano de la Bibliothèque Nationale de Paris - está estrechamente vinculada con el estudio epigráfico e iconográfico de los documentos allí contenidos. Se trata de la colección de Joseph Marius Alexis Aubin, intelectual francés desembarcado en México en 1830 con el fin de emprender investigaciones físicas y astronómicas por cuenta de la secretaría fra...

  5. 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.

  6. 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.

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

    CERN Document Server

    Villanueva, J R

    2015-01-01

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

  8. Gravitational scattering within the Himalia group of jovian prograde irregular satellites

    Science.gov (United States)

    Christou, Apostolos A.

    2005-03-01

    We test the hypothesis that gravitational scattering within the Himalia prograde irregular satellite group is responsible for the large velocity dispersion identified by Nesvorný et al. (2003, Astron. J. 126, 398-429). We carry out numerical simulations of the dynamical evolution of this group under several scenarios for Himalia's mass for 10 yr. We find that modification of the satellite orbits is significant, 10-15% of their semimajor axes differences but Caliban and Sycorax at Uranus and Nereid at Neptune.

  9. Dark matter massive fermions and Einasto profiles in galactic haloes

    Science.gov (United States)

    Siutsou, I.; Argüelles, C. R.; Ruffini, R.

    2015-07-01

    On the basis of a fermionic dark matter model we fit rotation curves of The HI Nearby Galaxy Survey (THINGS) sample and compare our 3-parametric model to other models widely used in the literature: 2-parametric Navarro-Frenk-White, pseudoisothermal sphere, Burkhert models, and 3-parametric Einasto model, suggested as the new "standard dark matter profile" model in the paper by Chemin et al., Astron. J. 142 (2011) 109. The results from the fitting procedure provides evidence for an underlying fermionic nature of the dark matter candidate, with rest mass above the keV regime.

  10. Do 'astronomês' para o português : a comunicação entre astrônomos e jornalistas no Brasil

    OpenAIRE

    2015-01-01

    Este trabalho tem o objetivo de fazer um "raio-x" das reportagens brasileiras sobre astronomia, astronáutica e áreas correlatas da exploração espacial a partir da ação dos três principais atores deste processo: pesquisadores, jornalistas e assessores de imprensa. Investigar o processo de produção e identificar as características subjacentes à cobertura desta temática tem particular relevância em um momento que o país está prestes a fazer investimentos bilionários para participar de grandes co...

  11. O imaginário extraterrestre na cultura portuguesa : do fim da Modernidade até meados do séc. XIX

    OpenAIRE

    Conceição, Joaquim Fernandes da

    2004-01-01

    Procede-se a uma inventariação de fontes de diverso teor que refiram ideias, conceitos e representações cosmológicas e astronómicas, especificamente conotadas com o âmbito "extraterrestre" e as noções sobre o Outro não terrestre e porventura não-humano. Analisa-se a rede de influências, mormente de leituras, que possam ter determinado as opções dos nossos mentores culturais sobre o tema.

  12. 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.

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

    Directory of Open Access Journals (Sweden)

    J. Echevarría

    2007-01-01

    Full Text Available 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 clase 6.5-m?

  14. Site testing at San Pedro Mártir

    Directory of Open Access Journals (Sweden)

    J. Echeverría

    2003-01-01

    Full Text Available En este art culo revisamos el trabajo realizado para medir la turbulencia atmosf erica al nivel del suelo en el Observatorio Astron omico Nacional en San Pedro M artir. Arguimos, basados en resultados m as modernos obtenidos a lo largo de m as de una d ecada, que la mediana de la calidad de imagen es de 0.55 segundos de arco a una altura de 15m. Este an alisis comprueba que San Pedro M artir es uno de los mejores sitios del mundo en cuanto a calidad de imagen y probablemente el mejor.

  15. De la astronomía a la lingüistica: una experiencia didáctica en torno a los logaritmos

    OpenAIRE

    Hernandez, Benito; Bosco, Juan

    1995-01-01

    En un recorrido que empieza en las necesidades de los cálculos astronómicos y termina en la teoría de lenguajes formales, se propone un modelo que posee las mismas propiedades que los logaritmos, desde el punto de vista formal, aunque con ciertas limitaciones. Dicho modelo muestra que las propiedades de los logaritmos no son tan antinaturales como parece a primera vista, pudiendo no sólo ser aprendidas sino también ser aceptadas.

  16. San Juan y el cruce sanmartiniano. Desarrollo de una ruta histórica como herramienta de gestión política en turismo y el desarrollo local

    OpenAIRE

    Velasco Lalanne, Santiago

    2014-01-01

    El presente trabajo pretende transformarse en un aporte al desarrollo de la planificación turística tomando como "punta de lanza" la ruta sanmartiniana para generar desde ella una política pública turística para la localidad de Barreal, apoyada en diversos factores que complementaran el desarrollo y consolidación, tales como el turismo astronómico, de aventura, arqueológico, etc. Fil: Velasco Lalanne, Santiago. Universidad Nacional de Mar del Plata. Facultad de Ciencias Económicas y Social...

  17. 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.

  18. Strange star admitting Chaplygin equation of state in Finch-Skea spacetime

    Science.gov (United States)

    Bhar, Piyali

    2015-10-01

    In the present paper we propose a new model of an anisotropic strange star which admits the Chaplygin equation of state. The exterior spacetime is described by a Schwarzschild line element. The model is developed by assuming the Finch-Skea ansatz (Finch and Skea in Class. Quantum Gravity 6:467, 1989. We obtain the model parameters in closed form. Our model is free from a central singularity. Choosing some particular values for the parameter we show that our model corroborates the observational data of the strange star PSR J1614-2230 (Gangopadhyay et al. in Mon. Not. R. Astron. Soc. 431:3216, 2013.

  19. 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.

  20. Theory and simulation of the optical response of novel nanomaterials from visible to terahertz

    OpenAIRE

    Ameen Poyli, M.

    2015-01-01

    Los avances tecnológicos ocurridos a partir del siglo XVI han permitido explorar tanto el mundo microscópico como el macroscópico, gracias al desarrollo de dispositivos basados en lentes y espejos, desconocidos hasta entonces. El telescopio, inventado por Hans Lippershey y utilizado por Galileo Galilei y sus contemporáneos para realizar sus observaciones astronómicas, ha permitido revelar los misterios del cosmos. En la escala opuesta, el uso del microscopio por Zacharias Janssen, Rober...

  1. Prácticas colaborativas entre curaduría y educación: una propuesta para las colecciones de arte

    OpenAIRE

    Sánchez Lesmes, Ana María

    2013-01-01

    El presente trabajo final comprende tanto un trabajo de orden conceptual que se ocupa de reflexionar sobre las prácticas colaborativas entre curaduría y educación, como las memorias resultantes de los distintos procesos adelantados en el Observatorio Astronómico Nacional, el Museo de Arte Moderno de Medellín y el Museo de Arte Moderno de Bucaramanga. El primer apartado remite a un estudio teórico sobre las prácticas curatoriales y educativas, así como su relación en contextos m...

  2. Diurnal and Sub-Diurnal Terms of Nutation

    Science.gov (United States)

    2000-03-01

    microarcseconds. Fundamental arguments Tidal Terrestr . Amplitudes Chao lm ls F D ̂ code period rigid elastic Phase et al. 1 0 1 0 1 0 13:719 1...tidal contributions. Fundamental arguments Tidal Terrestr . Oceanic Atmospheric lm ls F D ̂ code period ampl. phase ampl. phase 1 0 2 0 2 1 Q1 1...2000" including crossed-nutation and spin- orbit coupling e ects," Astron. Astrophys. Suppl. Ser., 135, 111{131. Wahr, J. M., 1981, \\The forced

  3. 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.

  4. Oxygen abundance in local disk and bulge: chemical evolution with a strictly universal IMF

    Science.gov (United States)

    Caimmi, R.; Milanese, E.

    2009-09-01

    This paper has two parts: one about observational constraints related to the empirical differential oxygen abundance distribution (EDOD), and the other about inhomogeneous models of chemical evolution, in particular the theoretical differential oxygen abundance distribution (TDOD). In the first part, the EDOD is deduced from subsamples related to two different samples involving (i) N=532 solar neighbourhood (SN) stars within the range, -1.5Prochaska et al. in Astron. J. 120:2513, 2000); (3) the fit to thin disk data implies an oxygen abundance range similar to its thick disk counterpart, with the extension of conclusion (2) to the thin disk, and the evolution of the thick + thin disk as a whole (Haywood in Mon. Not. R. Astron. Soc. 388:1175, 2008) cannot be excluded; (4) leaving outside the outer halo, a fit to the data related to different environments is provided by models with a strictly universal IMF but different probabilities of a region being active, which implies different global efficiencies of the star formation rate; (5) a special case of stellar migration across the disk can be described by models with enhanced star formation, where a fraction of currently observed SN stars were born in situ and a comparable fraction is due to the net effect of stellar migration, according to recent results based on high-resolution N-body + smooth particle hydrodynamics simulations (Ro\\vskar et al. in Astrophys. J. Lett. 684:L79, 2008).

  5. 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.

  6. Deployable Camera (DCAM3) System for Observation of Hayabusa2 Impact Experiment

    Science.gov (United States)

    Sawada, Hirotaka; Ogawa, Kazunori; Shirai, Kei; Kimura, Shinichi; Hiromori, Yuichi; Mimasu, Yuya

    2017-02-01

    An asteroid exploration probe "Hayabusa2", that was developed by Japan Aerospace Exploration Agency (JAXA), was launched on December 3rd, 2014 to challenge complicated and accurate operations during the mission phase around the C-type asteroid 162137 Ryugu (1999 JU3) (Tsuda et al. in Acta Astron. 91:356-362, 2013). An impact experiment on a surface of the asteroid will be conducted using the Small Carry-on Impactor (SCI) system, which will be the world's first artificial crater creation experiment on asteroids (Saiki et al. in Proc. International Astronautical Congress, IAC-12.A3.4.8, 2012, Acta Astron. 84:227-236, 2013a; Proc. International Symposium on Space Technology and Science, 2013b). We developed a new micro Deployable CAMera (DCAM3) system for remote observations of the impact phenomenon applying our conventional DCAM technology that is one of the smallest probes in space missions and gained a great success in past Japanese mission IKAROS (Interplanetary Kite-craft Accelerated by Radiation Of the Sun). DCAM3 is a miniaturized separable unit that contains two cameras and radio communication devices for transmission image data to the mothership "Hayabusa2", and it observes the impact experiment at an unsafe region in where the "Hayabusa2" is difficult to stay because of a risk of exploding and impacting debris hitting. In this paper, we report details of the DCAM3 system and development results as well as our mission plan for the DCAM3 observation during the SCI experiment.

  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. The Universe Observation Center: an educational center devoted to Astronomy in Catalonia

    Science.gov (United States)

    Fernández, D.

    The Universe Observation Center (in Catalan language, Centre d'Observació de l'Univers, COU) is located in close proximity to the Montsec Astronomical Observatory (Observatori Astronòmic del Montsec, OAM), in eastern Catalonia (Spain). Both centers comprise the Montsec Astronomical Park (Parc Astronòmic Montsec, PAM), managed by the Consorci del Montsec. Montsec Mountain remains the finest location for astronomical observation in Catalonia, as demonstrated by a site-testing campaign conducted by the Astronomy and Meteorology Department of the University of Barcelona. The COU consists of a Central Building (including a permanent exhibition and three classrooms possessing broadband Internet access), the Telescope Park (two astronomical domes equipped with medium-size telescopes, a coelostat for solar observation, and a portable telescope park), the Eye of Montsec (a digital planetarium and, at the same time, an extremely innovative platform for sky observation) and the Garden of the Universe (a tour of the land surrounding the COU, visiting several areas within it). The COU will offer to the Spanish academic community a host of fascinating and unique activities in the fields of astronomy and geology. The Center is open not only to students (from primary school through university), but also to amateur astronomers, people interested in science and the general public.

  9. 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

  10. A meta-analysis of coordinate systems and bibliography of their use on Pluto from Charon's discovery to the present day

    Science.gov (United States)

    Zangari, Amanda

    2015-01-01

    This paper aims to alleviate the confusion between many different ways of defining latitude and longitude on Pluto, as well as to help prevent future Pluto papers from drawing false conclusion due to problems with coordinates. In its 2009 meeting report, the International Astronomical Union Working Group on Cartographic Coordinates and Rotational Elements redefined Pluto coordinates to follow a right-handed system (Archinal, B.A., et al. [2011a]. Celest. Mech. Dynam. Astron. 109, 101-135; Archinal, B.A., et al. [2011b]. Celest. Mech. Dynam. Astron. 110, 401-403). However, before this system was redefined, both the previous system (defining the north pole to be north of the invariable plane), and the "new" system (the right-hand rule system) were commonly used. A summary of major papers on Pluto and the system each paper used is given. Several inconsistencies have been found in the literature. The vast majority of papers and most maps use the right-hand rule, which is now the IAU system and the system recommended here for future papers.

  11. Site prospection at san pedro mártir

    Directory of Open Access Journals (Sweden)

    J. Bohigas

    2008-01-01

    Full Text Available Realizamos mediciones climatológicas y de seeing, en 5 sitios dentro del área reservada para uso astronómico en el Parque Nacional Sierra de San Pedro Mártir (SPM, durante al menos 15 noches en cada uno de ellos. Las variables climáticas se midieron con una estación meteorológica Davis y un anemómetro ultrasónico Metek. El seeing fue medido con un RoboDIMM fabricado por NOAO. Las mediciones climatológicas y de seeing fueron comparadas con las obtenidas simultáneamente con la instrumentación del Thirty Meter Telescope Project en el Observatorio Astronómico Nacional (OAN en SPM. Las diferencias de seeing son pequeñas en la mayor parte de los casos. Recomendamos que se realice una campaña de larga duración en Llano Alto 1, ya que es un sitio de fácil acceso y el seeing parece ser ligeramente mejor.

  12. 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...

  13. 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)

  14. 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.

  15. Constraints on the Number of Kuiper Belt Objects from the Deep Ecliptic Survey

    Science.gov (United States)

    Adams, Elisabeth R.; Elliot, J. L.; Kern, S. D.; Gulbis, A. A.; Buie, M. W.; Trilling, D. E.; Wasserman, L. H.

    2007-10-01

    The Deep Ecliptic Survey, or DES, was a systematic survey for Kuiper Belt Objects with primary observations from 1998-2005. Over 800 square degrees of the sky were surveyed, and the DES found roughly 40% of the 1200 objects with preliminary designations from the Minor Planet Center at the time of survey completion. By correcting the survey data for observational bias, we have calculated the probability of discovering each individual object. The probablities range from a high value of 0.38 for 2002PO149 (a Classical object -- see Elliot et al. 2005, Astron. J. 129, 1117 for definitions of the DES dynamical classes) to a low value of 2 x 10^-6 for 82158 (a Scattered Near object). From these probabilities, we can estimate the relative populations of different dynamical classes of objects, provided there are a sufficient number of objects in the class. A few dynamical classes, such as Classical and 3:2 Resonant objects, have enough members for relatively robust statistics, and we estimate the size distributions. We also compare the ratio of objects in different classes to theoretical predictions (Hahn & Malhotra 2005, Astron. J. 130, 2392), based on Neptune migration models. This work was supported, in part, by NSF Grants AST0406493 and AST0707609.

  16. 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

  17. 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

  18. Elemental abundance studies using the EBASIM spectrograph of the 2.1-m CASLEO Observatory telescope. I. The normal stars 5 Aqr and 30 Peg

    Science.gov (United States)

    Adelman, Saul J.; López-Garcia, Zulema; Malaroda, Stella M.; Núñez, Natalia; Grosso, Mónica

    2004-12-01

    Using data from the new EBASIM spectrograph at the 2.1-m telescope of the Complejo Astronómico El Leoncito (CASLEO), two rather sharp-lined B stars 5 Aqr (=HD 198667, B9 III) and 30 Peg (=HD 211924, B5 IV) are being studied. The measurements are compared with those from the coudé spectrograph of the 1.22-m telescope of the Dominion Astrophysical Observatory (DAO). The equivalent width scales of the EBASIM and the DAO data are similar. As we found that the line profiles of 30 Peg are variable, we are trying to determine whether this star is a slowly pulsating B star. 5 Aqr has abundances close to those of the Sun.

  19. Photometric and integrated spectral study of the young open clusters Pismis 22, NGC 6178, NGC 6216 and Ruprecht 130

    Science.gov (United States)

    Piatti, A. E.; Clariá, J. J.; Bica, E.

    2000-08-01

    We present CCD observations in the B, V , and I passbands obtained for stars in the fields of the open clusters Pismis 22, NGC 6178, NGC 6216, and Ruprecht 130, projected not far from the Galactic centre (|l| b| Complejo Astronómico El Leoncito, which is operated under agreement between the Consejo Nacional de Investigaciones Científicas y Técnicas de la Repúbica Argentina and the National Universities of La Plata, Córdoba, and San Juan, Argentina, and at the University of Toronto (David Dunlap Observatory) 24-inch telescope, Las Campanas, Chile. Tables 3-6 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/Abstract.html

  20. Astrología, astronomía y filosofía de los principios en Platón

    OpenAIRE

    Lisi, Francisco Leonardo

    1991-01-01

    El trabajo destaca la importancia de la astronomía en la filosofía platónica analizando su posición en la República: constituye, con la aritmética, la geometría y la estereometría, el quadrivium introductorio en la educación de los guardianes. Pero, para Platón, la astronomía tiene no sólo un interés teórico, sino también práctico. Sus teorías astronómicas están vinculadas con la llamada "filosofía no escrita". Se estudia aquís esta concepción platónica de la astronomía en ambos niveles, teór...

  1. Astronomía: historia y calendario

    OpenAIRE

    Toro y Llaca, Carmen de

    1999-01-01

    I. EVOLUCIÓN DE LOS CONOCIMIENTOS ASTRONÓMICOS A TRAVÉS DE LA HISTORIA l. Hipótesis primitivas 2. Los períodos Clásico y Helenístico de la ciencia griega 3. La época de la oscuridad, Bizancio y la ciencia árabe 4. La obra astronómica de Alfonso X el Sabio 5. La Revolución Copemicana 6. La Edad de Oro de la astronomía de posición 7. La astronomía en el siglo XVIII. Nacimiento de la geodesia como ciencia independiente 8. Siglos XIX y Xx. Nacimiento y desarrollo de la astrofísica 9. La astronomí...

  2. Astronomía: historia y calenario

    OpenAIRE

    Toro y Llaca, Carmen de

    1999-01-01

    I. EVOLUCIÓN DE LOS CONOCIMIENTOS ASTRONÓMICOS A TRAVÉS DE LA HISTORIA l. Hipótesis primitivas 2. Los períodos Clásico y Helenístico de la ciencia griega 3. La época de la oscuridad, Bizancio y la ciencia árabe 4. La obra astronómica de Alfonso X el Sabio 5. La Revolución Copemicana 6. La Edad de Oro de la astronomía de posición 7. La astronomía en el siglo XVIII. Nacimiento de la geodesia como ciencia independiente 8. Siglos XIX y Xx. Nacimiento y desarrollo de...

  3. SPECKLE INTERFEROMETRY AT THE OBSERVATORIO ASTRONÓMICO NACIONAL. II

    Directory of Open Access Journals (Sweden)

    V. G. Orlov

    2010-01-01

    Full Text Available Presentamos mediciones interferométricas de motas para estrellas binarias, obtenidas en junio de 2009 en el telescopio de 1.5 m del Observatorio Astronómico Nacional en San Pedro Mártir (México. Nuestros datos comprenden 189 mediciones de ángulos de posición y separaciones de 144 sistemas. Las separaciones angulares medidas abarcan desde 0".16 hasta 3".64. La magnitud máxima de la componente más brillante es de 10.96. El error medio en las separaciones es de 0".02 y en los ángulos de posición de 1.5°. Algunos ángulos de posición se determinaron con la ambigüedad usual de 180°.

  4. SPECKLE INTERFEROMETRY AT THE OBSERVATORIO ASTRONÓMICO NACIONAL. III

    Directory of Open Access Journals (Sweden)

    V. G. Orlov

    2011-01-01

    Full Text Available Se presentan las mediciones interferométricas de motas de estrellas binarias realizadas durante agosto de 2010 con el telescopio 1.5 m y en noviembre de 2010 con el telescopio de 2.1 m del Observatorio Astronómico Nacional en SPM (Mexico. Los resultados reportados aquí son 238 mediciones de 225 pares con una magnitud límite de V = 12.2. De éstas, 211 parejas presentan separaciones de menos de 1. El error medio obtenido en la separación es de 0.02 y en el ángulo de posición de 1.5. Algunos de los ángulos de posición se determinaron con los 180 usuales de ambigüedad.

  5. 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).

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  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. Non-thermal emission from relativistic MHD simulations of PWNe: from synchrotron to inverse Compton

    CERN Document Server

    Volpi, D; Amato, E; Bucciantini, N

    2008-01-01

    In this paper we complete the set of diagnostic tools for synchrotron emitting sources presented by Del Zanna et al. (Astron. Astrophys. 453, 621, 2006) with the computation of inverse Compton radiation from the same relativistic particles. Moreover we investigate, for the first time, the gamma-ray emission properties of Pulsar Wind Nebulae in the light of the axisymmetric jet-torus scenario. The method consists in evolving the relativistic MHD equations and the maximum energy of the emitting particles. The particle energy distribution function is split in two components: the radio one connected to a relic population born at the outburst of the supernova and the other associated to the wind population continuously accelerated at the termination shock and emitting up to the gamma-ray band. We consider the general Klein-Nishina cross section and three different photon targets: the nebular synchrotron photons, far-infrared thermal ones and the cosmic microwave background. The overall synchrotron spectrum is fitt...

  13. ROBOTIC OPERATION OF THE DAO 1.2-M TELESCOPE AND MCKELLAR SPECTROGRAPH

    Directory of Open Access Journals (Sweden)

    D. Monin

    2014-01-01

    Full Text Available El telescopio de 1.2m DAO ha sido utilizado exitosamente par a obtener espectros astron ́omicos de modo rob ́otico desatendido durante una d ́ecada y aproximadamen te 2/3 de las noches programadas en el telescopio son utilizadas de esta manera ahora. La disponibilidad de es te tipo de operaci ́on rob ́otica ha impulsado la tasa de subscripci ́on del telescopio por aproximadamente 50% de sde que los usuarios del telescopio ya no tienen que viajar a Victoria para llevar a cabo sus programas de observa ci ́on. Se presenta un resumen del sistema rob ́otico y algunos detalles de su operaci ́on.

  14. Digitalización de espectros fotográficos de standards MK

    Science.gov (United States)

    Corti, M.; Morrell, N.

    Se digitalizaron 70 espectros fotográficos de estrellas standards de clasificación MK con tipos espectrales comprendidos entre O3 y A2 y diferentes clases de luminosidad. Las observaciones utilizadas consisten en espectrogramas cuya dispersión recíproca es de 43 Å~mm-1, obtenidos con el telescopio de 1m de Cerro Tololo y su espectrógrafo Cassegrain, durante los años 1982 a 1985. Los trazados digitales se obtuvieron con el instrumento Grant de la Facultad de Ciencias Astronómicas y Geofísicas de La Plata y posteriormente fueron calibrados en longitud de onda y rectificados utilizando rutinas comprendidas dentro del paquete de procesamiento de imágenes IRAF. El material resultante puede utilizarse como ayuda para la clasificación de espectros obtenidos con similar configuración instrumental.

  15. SOFTWARE AND ELECTRONIC DEVELOPMENTS FOR TUG - T60 ROBOTIC TELESCOPE

    Directory of Open Access Journals (Sweden)

    Murat Parmaksizoglu

    2014-01-01

    Full Text Available Un telescopio rob ́otico es un telescopio que puede realizar observaciones sin intervenci ́on humana en persona. Su comportamiento base es autom ́atico y controlado por orde nador. Los telescopios rob ́oticos suelen funcionar bajo el control de un planificador, que provee control de alto nivel seleccionando objetivos astron ́omicos para observar. El telescopio rob ́otico T60 del observatorio nac ional de TUBITAK 2 (TUG es controlado por el software c ́odigo abierto OCAAS, anteriormente llamado TAL ON. Este estudio introduce las mejoras sobre el software TALON, y nuevos dise ̃nos electr ́onicos y mec ́an icos. Las mejoras de dise ̃no y software han sido implementadas en el sistema de control del telescopio T60 y p robadas en el sistema real exitosamente.

  16. CESAR: A ROBOTIC TELESCOPE NETWORK TO SCIENCE AND PUBLIC OUTREACH

    Directory of Open Access Journals (Sweden)

    L. Cuesta

    2014-01-01

    Full Text Available CESAR es una red de instalaciones astron ́omicas que pone a disposici ́on de la sociedad una amplia variedad de telescopios que cubre la mayor ́ıa de las t ́ecnicas observacionales, desde la Radioastronom ́ıa hasta el ́optico, i n c l u y e n d o l a o b s e r v a c i ́ o n s o l a r . A l m e n o s e s t a r ́ a n d i s p o n i b l e s p a r a e s t e p r o y e c t o c i n c o t e l e s c o p i o s.

  17. 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.

  18. 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.

  19. Supernovas, faros en el universo: medición de la distancia a ASASSN-15hx

    Directory of Open Access Journals (Sweden)

    Ramona Núñez López

    2016-12-01

    Full Text Available Difícil pensar en un evento astronómico tan relevante y polifacético como la gigantesca explosión de supernova, que en breves segundos destruye su estrella, creando un gran número de elementos pesados. El inmenso brillo de las supernovas permite observarlas a enormes distancias, para así obtener información cosmológica. En este trabajo abordamos en general el tema de supernovas, enfocándonos luego al estudio de la supernova de tipo Ia ASASSN-15hx. Presentamos las observaciones realizadas en diferentes filtros y mostramos un método basado en el ancho de su curva de luz para estimar su distancia y corrimiento al rojo. Los valores obtenidos coinciden con información encontrada en la literatura y las incertidumbres obtenidas están dentro del rango de las encontradas con otros métodos.

  20. 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.

  1. 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.

  2. Theory and Simulations of Refractive Substructure in Resolved Scatter-Broadened Images

    CERN Document Server

    Johnson, Michael D

    2015-01-01

    At radio wavelengths, scattering in the interstellar medium distorts the appearance of astronomical sources. Averaged over a scattering ensemble, the result is a blurred image of the source. However, Narayan & Goodman (1989) and Goodman & Narayan (1989) showed that for an incomplete average, scattering introduces refractive substructure in the image of a point source that is both persistent and wideband. We show that this substructure is not smoothed by an extended source and that the scattering can therefore introduce spurious compact features into images that would be resolved in the absence of scattering. In addition, we derive efficient strategies to numerically compute realistic scattered images, and we present characteristic examples from simulations. Our results show that refractive substructure is an important consideration for ongoing missions at the highest angular resolutions, and we discuss specific implications for RadioAstron and the Event Horizon Telescope.

  3. The Telescopio San Pedro Mártir project

    Science.gov (United States)

    Richer, Michael G.; Lee, William H.; González, Jesús; Jannuzi, Buell T.; Sánchez, Beatriz; Rosales Ortega, Fabián.; Alcock, Charles; Carramiñana Alonso, Alberto; García Díaz, Ma. Teresa; Gutiérrez, Leonel; Herrera, Joel; Hill, Derek; Norton, Timothy J.; Pedrayes, Maria H.; Pérez-Calpena, Ana; Reyes-Ruíz, Mauricio; Serrano Guerrero, Hazael; Sierra, Gerardo; Teran, Jose; Urdaibay, David; Uribe, Jorge A.; Watson, Alan M.; Zaritsky, Dennis; García Vargas, Marisa

    2016-07-01

    The Telescopio San Pedro Mártir project intends to construct a 6.5m telescope to be installed at the Observatorio Astronómico Nacional in the Sierra San Pedro Mártir in northern Baja California, Mexico. The project is an association of Mexican institutions, lead by the Instituto Nacional de Astrofísica, Óptica y Electrónica and the Instituto de Astronomía at the Universidad Nacional Autónoma de México, in partnership with the Smithsonian Astrophysical Observatory and the University of Arizona's Department of Astronomy and Steward Observatory. The project is currently in the planning and design stage. Once completed, the partners plan to operate the MMT and TSPM as a binational astrophysical observatory.

  4. 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

  5. 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.

  6. 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.

  7. 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.

  8. 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

  9. 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.

  10. Probabilities for Solar Siblings

    Science.gov (United States)

    Valtonen, Mauri; Bajkova, A. T.; Bobylev, V. V.; Mylläri, A.

    2015-02-01

    We have shown previously (Bobylev et al. Astron Lett 37:550-562, 2011) that some of the stars in the solar neighborhood today may have originated in the same star cluster as the Sun, and could thus be called Solar Siblings. In this work we investigate the sensitivity of this result to galactic models and to parameters of these models, and also extend the sample of orbits. There are a number of good candidates for the sibling category, but due to the long period of orbit evolution since the break-up of the birth cluster of the Sun, one can only attach probabilities of membership. We find that up to 10 % (but more likely around 1 %) of the members of the Sun's birth cluster could be still found within 100 pc from the Sun today.

  11. 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.

  12. 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.

  13. 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

  14. 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.

  15. Repaso del Sabio Caldas

    Directory of Open Access Journals (Sweden)

    Jaime Paredes Pardo

    1983-01-01

    Full Text Available En Popayán aún se conserva la casa donde nació el sabio Francisco José de Caldas. Está situada en la esquina de la carrera 5a. con la calle 3a., en pleno barrio de la Pamba. Es una construcción robusta de líneas austeras y como especialidad única cuenta con un patio en cuyo centro se levanta un observatorio astronómico, obra del propio Caldas cuando estaba joven. Varios instrumentos que le fueron útiles fabricó para el observatorio, desde donde podía seguir el giro de los astros. Antes cuando era apenas un niño, su madre tenía que reprenderlo con alguna frecuencia porque tardaba demasiado en el estudio de los libros.

  16. 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.

  17. Los cuadrantes solares en la arquitecturas nuevos diseños

    OpenAIRE

    Raya Román, José María

    1985-01-01

    La Tesis se ha dividido en seis partes, desarrolladas en los capítulos II al VII. En la primera parte, Modelos planetario Capítulo II- se define un sistema sol-tierra geocéntrico que cumplirá con las leyes de Kepler con lo que las posiciones que se obtengan, a partir de dicho sistema, del sol en su órbita aparente, se corresponderán con las posiciones reales del mismo...En la segunda parte, Cálculo gráfico astronómico, -capítulo III-, se desarrolla un método de cálculo gráfico basado en la r...

  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. 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.

  20. 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.

  1. 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...

  2. SUPERFAST THERMALIZATION OF PLASMA

    Science.gov (United States)

    Chang, C.C.

    1962-06-12

    A method is given for the superfast thermalization of plasma by shock conversion of the kinetic energy stored in rotating plasma rings or plasmoids colliding at near supersonic speeds in a containment field to heat energy in the resultant confined plasma mass. The method includes means for generating rotating plasmoids at the opposite ends of a Pyrotron or Astron containment field. The plasmoids are magnetically accelerated towards each other into the opposite ends of time containment field. During acceleration of the plasmoids toward the center of the containment field, the intensity of the field is sequentially increased to adiabatically compress the plasmoids and increase the plasma energy. The plasmoids hence collide with a violent shock at the eenter of the containment field, causing the substantial kinetic energy stored in the plasmoids to be converted to heat in the resultant plasma mass. (AEC)

  3. 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.

  4. 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.

  5. La gravedad en Bruno, Kleper y Newton. la distribución de la materia y sus implicaciones cosmológicas

    Directory of Open Access Journals (Sweden)

    M. Diego Pintado

    2016-10-01

    Full Text Available En este trabajo se describe en modo sucinto el papel fundamental y determinante del problema de la gravitación universal en la historia de la cosmología moderna, indagándose así mismo los factores que le dieron origen, principalmente la proposición de la formulación de la ley de gravedad, sus antecedentes, y a su vez se repasan los problemas astrofísicos, astronómicos y filosóficos de este nuevo esquema cosmológico. El esquema de esta monografía traza un breve examen epistemológico, luego un repaso por el origen y gestación del concepto de gravitación universal, y finalmente un análisis del desarrollo de la cosmología moderna, o newtoniana, entorno a los problemas implicados por la ley de gravedad.

  6. Los hebreos: Un legado religioso

    Directory of Open Access Journals (Sweden)

    Ligia Carvajal Mena

    2014-11-01

    Full Text Available Los primeros asentamientos humanos tuvieron lugar en las riberas de ríos como el Éufrates, Tigris y Nilo. Estas tierras, por su fertilidad, se convirtieron en cuna de culturas que dejaron un legado importante para el desarrollo de la humanidad. En el marco de esas culturas destaca la hebrea que asume aspectos culturales foráneos, los recompone y da un salto original en su cultura, especialmente en el ámbito religioso. Lo anterior al establecer inequívocamente el monoteísmo, realizar mejores construcciones (entre lo religioso y lo astronómico y crear un Dios con fuerte contenido ético, que trasciende del ámbito nacional al universal.

  7. Errores sistemáticos del Catálogo Fundamental FK5, deducidos de las observaciones con Astrolabio Fotoeléctrico PAII, en el Hemisferio Sur

    Science.gov (United States)

    Manrique, W. T.; Podestá, R. C.; Alonso, E.; Actis, E. V.; Pacheco, A. M.; Bustos, G.; Lizhi, L.; Zezhi, W.; Fanmiao, Z.; Hongqi, W.; Perdomo, R.; González, A.; Gómez, G.

    Se dan los resultados obtenidos de los Errores Sistemáticos del Catálogo Fundamental FK5, Δ α δ, Δ α α, Δ δ α y Δ δ δ, derivados de las observaciones estelares con el Astrolabio Fotoeléctrico PAII del Observatorio de Beijing instalado en el Observatorio Astronómico ``Félix Aguilar'' de San Juan, de acuerdo al Proyecto de Colaboración entre los observatorios de San Juan, Beijing y La Plata. Se han usado los residuos seleccionados de 11000 estrellas aproximadamente, derivados de más de 400000 pasajes estelares en 1550 días, desde Febrero de 1992 a Marzo de 1997. La precisión media de los residuos es de 0,"043.

  8. Contaminación de luz en Michoacán (campaña para cielos oscuros)

    OpenAIRE

    2001-01-01

    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 notabl...

  9. 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.

    2016-11-01

    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).

  10. Giant pulses of the Crab Nebula pulsar as an indicator of a strong electromagnetic wave

    Science.gov (United States)

    Popov, M. V.; Rudnitskii, A. G.; Soglasnov, V. A.

    2017-03-01

    The spectra and visibility functions of giant pulses of the Crab Nebula pulsar derived from VLBI observations carried out through the "RadioAstron" project in 2015 are analyzed. Parameters of the scattering of the pulses in the interstellar medium are measured, namely, the scattering time and decorrelation bandwidth. A comparative analysis of the shapes of the spectra and visibility functions of giant pulses obtained in real observations and via modeling of their scattering is carried out. The results suggest the presence of short bursts ( dt leading to the generation of additional radiation perpendicular to the direction of propagation of the giant pulses. This radiation may be associated with anomalous components of the mean pulse profile observed at frequencies above 4 GHz.

  11. Polarimetry of M-type asteroids

    Science.gov (United States)

    Gil-Hutton, R.

    2007-03-01

    Aims:Results of a polarimetric program at Complejo Astronómico El Leoncito (Casleo), San Juan, Argentina are presented. The aim of this campaign is to estimate the polarimetric properties of asteroids belonging to the X taxonomic class. In this paper results of the campaign for M-type objects are presented. Methods: The data have been obtained with Casprof and Torino polarimeters at the 2.15 m telescope. The Casprof polarimeter is a two-hole aperture polarimeter with rapid modulation and the Torino polarimeter is an instrument that allows simultaneous measurement of polarization in the U-, B-, V-, R-, and I-bands. Results: The campaign began in 2000, and data on a sample of 26 M-type asteroids were obtained. Most of these objects were polarimetricaly observed for the first time. Combining these data with those available in the literature, an estimate of the polarimetric parameters and albedo for 12 objects is presented. Furthermore, the data show that asteroids 21 Lutetia and 77 Frigga have a large inversion angle and 441 Bathilde a deep polarization minimum, implying a controversial taxonomic classification as M-type for these objects. Also, the polarimetric parameters estimated for the M-type asteroids showing in their spectra the 3 μm band and classified as W-type by Rivkin et al. (1995, Icarus, 117, 90; 2000, ApJ, 145, 351) could be different from those without that feature. Based on observations carried out at the 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.

  12. Polarimetric survey of main-belt asteroids. II. Results for 58 B- and C-type objects

    Science.gov (United States)

    Gil-Hutton, R.; Cañada-Assandri, M.

    2012-03-01

    Aims: We present results of a polarimetric survey of main-belt asteroids at Complejo Astronómico el Leoncito (CASLEO), San Juan, Argentina. The aims of this survey are to increase the database of asteroid polarimetry, to estimate diversity in polarimetric properties of asteroids that belong to different taxonomic classes, and to search for objects that exhibit anomalous polarimetric properties. Methods: The data were obtained with the Torino and CASPROF polarimeters at the 2.15m telescope. The Torino polarimeter is an instrument that allows simultaneous measurement of polarization in five different bands, and the CASPROF polarimeter is a two-hole aperture polarimeter with rapid modulation. Results: The survey began in 2003, and up to 2009 data on a sample of more than 170 asteroids were obtained. In this paper the results for 58 B- and C-type objects are presented, most of them polarimetrically observed for the first time. Using these data we find phase-polarization curves and polarimetric parameters for these taxonomic classes. Based on observations carried out at the 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.Tables 1 and 2 are available in electronic form at CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/539/A115

  13. The Universe Observing Center a modern center to teach and communicate astronomy

    Science.gov (United States)

    Ribas, Salvador J.

    2011-06-01

    The Universe Observing Center is one of the parts of the Parc Astronòmic Montsec (PAM). PAM is an initiative of the Catalan government, through the Consorci del Montsec (Montsec Consortium), to take advantage of the capabilities and potential of the Montsec region to develop scientific research, training and outreach activities, particularly in the field of Astronomy. The choice of the Montsec mountains to install the PAM was motivated by the magnificent conditions for observing the sky at night; the sky above Montsec is the best (natural sky free of light pollution) in Catalonia for astronomical observations. The PAM has two main parts: the Observatori Astronòmic del Montsec (OAdM) and the Universe Observing Center (COU). The OAdM is a professional observatory with an 80-cm catadioptric telescope (Joan Oró Telescope). This telescope is a robotic telescope that can be controlled from anywhere in the world via the Internet. The COU is a large multipurpose center which is intended to become an educational benchmark for teaching and communicate astronomy and other sciences in Catalonia. The management of the COU has three main goals: 1) Teach primary and secondary school students in our Educational Training Camp. 2) Teach university students housing the practical astronomy lectures of the universities. 3) Communicate astronomy to the general public. The COU comprises special areas for these purposes: the Telescopes Park with more than 20 telescopes, a coelostat for solar observations and two dome containing full-automated telescopes. The most special equipment is ``The Eye of Montsec'', with its 12m dome containing a multimedia digital planetarium and a platform for direct observation of the sky and the environment. During 2009 we expect around 10000 visitors in Montsec area to enjoy science with Montsec dark skies and an special natural environment.

  14. The effects of ablation on the cross section of planetary envelopes at capturing planetesimals

    Science.gov (United States)

    Benvenuto, Omar G.; Brunini, Adrián

    2008-06-01

    We explore the cross section of giant planet envelopes at capturing planetesimals of different sizes. For this purpose we employ two sets of realistic planetary envelope models (computed assuming for the protoplanetary nebula masses of 10 and 5 times the mass of the minimum mass solar nebula), account for drag and ablation effects and study the trajectories along which planetesimals move. The core accretion of these models has been computed in the oligarchic growth regime [Fortier, A., Benvenuto, O.G., Brunini, A., 2007. Astron. Astrophys. 473, 311-322], which has also been considered for the velocities of the incoming planetesimals. This regime predicts velocities larger that those used in previous studies of this problem. As the rate of ablation is dependent on the third power of velocity, ablation is more important in the oligarchic growth regime. We compute energy and mass deposition, fractional ablated masses and the total cross section of planets for a wide range of values of the critical parameter of ablation. In computing the total cross section of the planet we have included the contributions due to mass deposited by planetesimals moving along unbound orbits. Our results indicate that, for the case of small planetary cores and low velocities for the incoming planetesimals, ablation has a negligible impact on the capture cross section in agreement with the results presented in Inaba and Ikoma [Inaba, S., Ikoma, M., 2003. Astron. Astrophys. 410, 711-723]. However for the case of larger cores and high velocities of the incoming planetesimals as predicted by the oligarchic growth regime, we find that ablation is important in determining the planetary cross section, being several times larger than the value corresponding ignoring ablation. This is so regardless of the size of the incoming planetesimals.

  15. Inauguração do Telescópio SOAR

    Science.gov (United States)

    Steiner, João

    2004-04-01

    A comunidade astronômica brasileira de há muito almeja ter a sua disposição um instrumento científico com o qual possa fazer pesquisa de vanguarda e manter a competitividade científica a nível internacional. Hoje este sonho se torna uma realidade. O Brasil tem tido uma política de pesquisa e de pós-graduação bem sucedida. Estamos formando 7000 doutores por ano e produzimos 1,5% da ciência mundial. Nosso desafio, hoje, é associar a esta capacidade de gerar conhecimento também a capacidade de usar o conhecimento em beneficio da sociedade. A Astronomia não é exceção. Temos 7 programas de pós-graduação em nível de doutorado e 11 em nível de mestrado. O telescópio SOAR será o principal instrumento que sustentará estes programas nas próximas décadas. A inauguração do telescópio SOAR simboliza de forma concreta e decidida o apoio do MCT, do CNPq e da FAPESP para o financiamento à pesquisa básica em nosso país. O Laboratório Nacional de Astrofísica, criado a cerca de 20 anos pelo CNPq, a par do Laboratório Nacional de Luz Sincrotron, são até hoje, os únicos laboratórios nacionais do Brasil e ambos voltados basicamente ao avanço do conhecimento. Os vinte anos de existência do LNA foram decisivos para a estruturação da comunidade astronômica no Brasil e para a construção das parcerias como o SOAR.

  16. 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.

  17. Electron impact excitation of N3+ using the B-spline R-matrix method: importance of the target structure description and the size of the close-coupling expansion

    Science.gov (United States)

    Fernández-Menchero, L.; Zatsarinny, O.; Bartschat, K.

    2017-03-01

    There are major discrepancies between recent intermediate coupling frame transformation (ICFT) and Dirac atomic R-matrix code (DARC) calculations (Fernández-Menchero et al 2014 Astron. Astrophys. 566 A104; Aggarwal et al 2016 Mon. Not. R. Astron. Soc. 461 3997) regarding electron-impact excitation rates for transitions in several Be-like ions, as well as claims that the DARC calculations are much more accurate and the ICFT results might even be wrong. To identify possible reasons for these discrepancies and to estimate the accuracy of the various results, we carried out independent B-spline R-matrix calculations for electron-impact excitation of the Be-like ion {{{N}}}3+. Our close-coupling (CC) expansions contain the same target states (238 levels overall) as the previous ICFT and DARC calculations, but the representation of the target wave functions is completely different. We find close agreement among all calculations for the strong transitions between low-lying states, whereas there remain serious discrepancies for the weak transitions as well as for transitions to highly excited states. The differences in the final results for the collision strengths are mainly due to differences in the structure description, specifically the inclusion of correlation effects, rather than the treatment of relativistic effects or problems with the validity of the three methods to describe the collision. Hence there is no indication that one approach is superior to another, until the convergence of both the target configuration and the CC expansions have been fully established.

  18. Polarimetric survey of main-belt asteroids. V. The unusual polarimetric behavior of V-type asteroids

    Science.gov (United States)

    Gil-Hutton, R.; López-Sisterna, C.; Calandra, M. F.

    2017-03-01

    Aims: We present the results of a polarimetric survey of main-belt asteroids at Complejo Astronómico El Leoncito (CASLEO), San Juan, Argentina. The aims of this survey are to increase the database of asteroid polarimetry, to estimate diversity in polarimetric properties of asteroids that belong to different taxonomic classes, and to search for objects that exhibit anomalous polarimetric properties. Methods: The data were obtained using the CASPROF and CASPOL polarimeters at the 2.15 m telescope. The CASPROF polarimeter is a two-hole aperture polarimeter with rapid modulation and CASPOL is a polarimeter based on a CCD detector, which allows us to observe fainter objects with better signal-to-noise ratio. Results: The survey began in 1995 and data on a large sample of asteroids were obtained until 2012. A second period began in 2013 using a polarimeter with a more sensitive detector in order to study small asteroids, families, and special taxonomic groups. We obtained 55 polarimetric measurements for 28 V-type main belt asteroids, all of them polarimetrically observed for the first time. The data obtained in this survey let us find polarimetric parameters for (1459) Magnya and for a group of 11 small V-type objects with similar polarimetric behavior. These polarization curves are unusual since they show a shallow minimum and a small inversion angle in comparison with (4) Vesta, although they have a steeper slope at α0. This polarimetric behavior could be explained by differences in the regoliths of these asteroids. The observations of (2579) Spartacus, and perhaps also (3944) Halliday, indicate a inversion angle larger than 24-25°. Based on observations carried out at the 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. 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.

  20. 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.

  1. "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

  2. 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.

  3. Theory for planetary exospheres: I. Radiation pressure effect on dynamical trajectories

    Science.gov (United States)

    Beth, A.; Garnier, P.; Toublanc, D.; Dandouras, I.; Mazelle, C.

    2016-03-01

    The planetary exospheres are poorly known in their outer parts, since the neutral densities are low compared with the instruments detection capabilities. The exospheric models are thus often the main source of information at such high altitudes. We present a new way to take into account analytically the additional effect of the radiation pressure on planetary exospheres. In a series of papers, we present with an Hamiltonian approach the effect of the radiation pressure on dynamical trajectories, density profiles and escaping thermal flux. Our work is a generalisation of the study by Bishop and Chamberlain (Bishop, J., Chamberlian, J.W. [1989]. Icarus 81, 145-163). In this first paper, we present the complete solutions of particles trajectories, which are not conics, under the influence of the solar radiation pressure with some assumptions. This problem is similar to the classical Stark problem (Stark, J. [1914]. Ann. Phys. 348, 965-982). This problem was largely tackled in the literature and more specifically, recently by Lantoine and Russell (Lantoine, G., Russell, R.P. [2011]. Celest. Mech. Dynam. Astron. 109, 333-366) and by Biscani and Izzo (Biscani, F., Izzo, D. [2014]. Mon. Not. R. Astron. Soc. 439, 810-822) as we will discuss in this paper. We give here the full set of solutions for the motion of a particle (in our case for an atom or a molecule), i.e. the space coordinates and the time solution for bounded and unbounded trajectories in terms of Jacobi elliptic functions. We thus provide here the complete set of solutions for this so-call Stark effect (Stark, J. [1914]. Ann. Phys. 348, 965-982) in terms of Jacobi elliptic functions (Jacobi, C.G.J. [1829]. Fundamenta nova theoriae functionum ellipticarum. Sumtibus fratrum), which may be used to model the trajectories of particles in planetary exospheres.

  4. 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.

  5. 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

  6. Essays on Eclipses, Transits and Occultations as Teaching Tools in the Introductory Astronomy College Course. (Spanish Title: Ensayos sobre Eclipses, Tránsitos y Ocultaciones Como Herramientas de Enseñanza en el Curso Universitario Introductorio a la Astronomía.) Ensaios sobre Eclipses, Trânsitos e Ocultações Como Ferramentas de Ensino em um Curso Universitário Introdutório de Astromomia

    Science.gov (United States)

    Dcruz, Noella L.

    2014-07-01

    We occasionally include projects in our learner-centered introductory astronomy college course to enable non-science major students explore some astronomical concepts in more detail than otherwise. Such projects also highlight ongoing or upcoming astronomical events. We hope that students will feel more interested in astronomy through projects tied to astronomical events. In Spring 2012, we offered short essays focused on eclipses, transits and occultations to promote the rare transit of Venus that occurred on June 5th, 2012. We asked students to write two short essays from three that were offered. The essays contained descriptive and conceptual parts. They were meant to serve as teaching tools. 62% of 106 essays from 55 students earned A, B or C grades. 21% of 47 feedback survey respondents felt the essays increased their interest in astronomy. 49% of respondents felt that the essays were not educationally beneficial and should not be offered again. The most common written response to our survey indicated that students need more guidance and better preparation in writing successful essays. Since students found the conceptual parts of the essays difficult, in the future we will provide relevant activities prior to essay deadlines to help students create successful essays. Ocasionalmente, incluimos proyectos en nuestro curso de introducción a la astronomía universitario centrado en el alumno para permitir que los estudiantes de carreras no científicas exploren algunos conceptos astronómicos en más detalle que lo habitual. Estos proyectos también ponen en relevancia eventos astronómicos en curso o futuros. Esperamos que los estudiantes se sientan más interesados en la astronomía a través de proyectos vinculados a eventos astronómicos. En el período de primavera de 2012 (EUA), propusimos breves ensayos centrados en los eclipses, tránsitos y ocultaciones para promover el raro tránsito de Venus que se produjo el 5 de junio de 2012. Le pedimos a los

  7. Modelo numérico tri-dimensional linear da plataforma continental do Estado do Maranhão Linear three-dimensional numerical model of Maranhão State continental shelf

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    José Edson Rodrigues Pereira

    1995-01-01

    Full Text Available Um modelo numérico hidrodinámico tri-dimensional linear, do tipo Heaps, foi implementado para a plataforma continental do Estado do Maranhão, visando a simulação da circulação gerada por efeitos astronômicos e meteorológicos na área. O modelo foi processado para cinco condições, a fim de calcular a circulação na plataforma devida aos seguintes efeitos: componente de maré semi-diurna lunar principal (M2, composição das principais componentes astronômicas de maré na área, condições meteorológicas médias de verão, condições meteorológicas médias de inverno e forçantes de maré em períodos específicos de interesse. Mapas cotidais e elipses de correntes da componente M2 foram obtidos, sendo esta componente preponderante na circulação local. Elevações e correntes sazonais médias são, em geral, muito menores que as astronômicas, permitindo o uso apenas de forçantes de maré em previsões hidrodinámicas. As simulações do modelo foram satisfatórias na plataforma e menos precisas nas baías e áreas internas rasas, onde atrasos de fase significativos são observados, devido a efeitos de menor escala que a adotada pelo modelo.A linear three-dimensional hydrodynamical numerical model, Heaps type, was implemented to the continental shelf of Maranhão State, aiming the simulation of the circulation generated by astronomical and meteorological effects in that area. Five runs of the model were performed, in order to compute the circulation in the shelf due to the following effects: principal lunar semi-diurnal component (M2, composition of the principal astronomical components in the area, mean summer meteorological conditions, mean winter meteorological conditions and tidal forcing in specific periods of interest. M2 cotidal maps and currents ellipses were obtained, that one being the most important component in the tidal circulation. Mean seasonal elevations and currents are generally much smaller than the

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

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    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

  9. 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

  10. Prospects for the characterization of exoplanet atmospheres

    Science.gov (United States)

    Lunine, J. I.

    2007-08-01

    -like stars makes possible the detection of planets approaching the size of Earth with transits, and the mass of Earth with the Doppler spectroscopic technique, as demonstrated recently in the discovery of a body with M sin i (i the inclination of the orbit to the star-observer line of sight) of 5.1 Earth masses (5). The mirror size and instrument sensitivities of JWST make it conceivable that transit spectroscopy of putative Earth-sized planets around solar neighborhood M dwarfs could detect major atmospheric or oceanic features if such planets exist with the right orbit inclinations (6). Detection of subtler but also more diagnostic clues to habitability (7) will require something more on the scale of ESA's planned Darwin mission. Meanwhile Corot, already in space, and Kepler, planned for launch in 2008, will provide a transit-based census of the occurrence of planets from Jovian down to terrestrial in size, allowing a better constrained strategy for extending spectroscopy to the numerous planetary systems in our cosmic neighborhood. References: (1) Lunine J.I. et al. in Jupiter ed. Bagenal et al., CUP, 2004. (2) Ehrenreich, D. et al. Astron. Astrophys. 448, 379, 2006. (3) Richardson, J.L. et al., Nature 445 892, 2007. (4) Gardner, J. et al., Space Science Reviews 123, 485, 2006. (5) Udry, S. et al., Astron Astrophys. submitted. (6) Valenti, J. et al. Astron. J. subm. 2007. (7) Tinetti G., et al. Ap.J. 644, L29, 2006.

  11. Deciphering the embedded wave in Saturn's Maxwell ringlet

    Science.gov (United States)

    French, Richard G.; Nicholson, Philip D.; Hedman, Mathew M.; Hahn, Joseph M.; McGhee-French, Colleen A.; Colwell, Joshua E.; Marouf, Essam A.; Rappaport, Nicole J.

    2016-11-01

    The eccentric Maxwell ringlet in Saturn's C ring is home to a prominent wavelike structure that varies strongly and systematically with true anomaly, as revealed by nearly a decade of high-SNR Cassini occultation observations. Using a simple linear "accordion" model to compensate for the compression and expansion of the ringlet and the wave, we derive a mean optical depth profile for the ringlet and a set of rescaled, background-subtracted radial wave profiles. We use wavelet analysis to identify the wave as a 2-armed trailing spiral, consistent with a density wave driven by an m = 2 outer Lindblad resonance (OLR), with a pattern speed Ωp = 1769.17° d-1 and a corresponding resonance radius ares = 87530.0 km. Estimates of the surface mass density of the Maxwell ringlet range from a mean value of 11g cm-2 derived from the self-gravity model to 5 - 12gcm-2 , as inferred from the wave's phase profile and a theoretical dispersion relation. The corresponding opacity is about 0.12 cm2 g-1, comparable to several plateaus in the outer C ring (Hedman, M.N., Nicholson, P.D. [2014]. Mont. Not. Roy. Astron. Soc. 444, 1369-1388). A linear density wave model using the derived wave phase profile nicely matches the wave's amplitude, wavelength, and phase in most of our observations, confirming the accuracy of the pattern speed and demonstrating the wave's coherence over a period of 8 years. However, the linear model fails to reproduce the narrow, spike-like structures that are prominent in the observed optical depth profiles. Using a symplectic N-body streamline-based dynamical code (Hahn, J.M., Spitale, J.N. [2013]. Astrophys. J. 772, 122), we simulate analogs of the Maxwell ringlet, modeled as an eccentric ringlet with an embedded wave driven by a fictitious satellite with an OLR located within the ring. The simulations reproduce many of the features of the actual observations, including strongly asymmetric peaks and troughs in the inward-propagating density wave. We argue that

  12. The Future of Astrometric Education

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    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

  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. Charon's Radius and Atmospheric Constraints from the 2005 July 11 Stellar Occultation

    Science.gov (United States)

    Gulbis, A. A. S.; Elliot, J. L.; Person, M. J.; Adams, E. R.; Kern, S. D.; Kramer, E. A.; Babcock, B. A.; Gangestad, J. W.; Pasachoff, J. M.; Souza, S. P.; Osip, D. J.; Emililo, M.; Tuvikene, T.

    2005-12-01

    On 2005 July 11 (UT), Charon occulted the star ``C313.2" (originally identified as a Pluto occultation star [McDonald & Elliot, Astron. J. 120, 1599, 2000]; UCAC2 26257135; R = 14.8). We arranged to observe this event using five telescopes at four sites: the 0.6-m at Pico dos Dias Obs. (Brazil), the 0.84-m at Obs. Cerro Armazones, the 2.5-m du Pont and 6.5-m Clay at Las Campanas Obs., and the 8-m Gemini South at Cerro Pacha (Chile). The observations were successful at all stations excluding Pico dos Dias, which was clouded out. The Acquisition Camera was employed at Gemini South, while the remaining sites used POETS (Portable Occultation, Eclipse, and Transit Systems). Each system utilized a high-speed camera, a control computer, and a GPS to establish accurate timing. The cameras contain back-illuminated CCDs, with > 90% quantum efficiency, ˜ 6 electrons read noise, and 1.74 ms deadtime during frame transfer. For this event, data rates were 2 - 10 Hz and signal-to-noise ratios were 28 - 273 (normalized to 1 s). The Clay telescope light curve had high enough time resolution and signal-to-noise to detect the first diffraction fringe. This dataset marks significant improvement over the only previously viewed stellar occultation by Charon (Walker, MNRAS 192, 47, 1980; Elliot & Young, Icarus 89, 244, 1991). By fitting the light curves with models derived from French and Gierasch (Astron. J. 81, 445, 1976), we have calculated Charon's radius and placed strong constraints on an atmosphere. These results seem consistent with a collisional origin of the Pluto-Charon system in which either of the precursor bodies may have been differentiated (McKinnon, Astrophys. J. Lett. 344, L41, 1989). Support provided, in part, by NASA Planetary Astronomy grants NNG04GE48G, NNG04GF25G, and NNH04ZSS001N, IAP P5/36 of the Belgian Federal Office, and BIL 01/3 of the Flemish Ministry.

  15. Los modelos etnomatemáticos de representación cosmogónica en los pueblos indígenas Americanos

    Directory of Open Access Journals (Sweden)

    Alejandro Jaén Rojas

    2015-01-01

    Full Text Available El propósito en este artículo es el de mostrar y analizar diversas formas de representación que utilizaron o, utilizan aun los indígenas americanos de diversas culturas. Algunas formas de representación, consideradas comúnmente como motivos decorativos, parecen responder a un sistema lógico muy preciso, que podría tener el propósito central de expresar y guardar conocimientos cosmogónicos. Para tal efecto, los indígenas de diversos pueblos, recurrieron a estructuras y formas de representación matemáticas, que les permitían guardar conocimientos astronómicos, calendáricos, de las cosechas, censos, entre otros, y luego expresarlos como mitos, integrados dentro de su espacio cosmogónico. Resulta sorprendente ver como algunas formas de representación, como las grecas escalonadas, pasan de una cultura a otra, desde Alaska hasta la Patagonia, en lo que parecen ser modelos de representación, que se difundieron muchos siglos antes de la llegada de los españoles a América. La razón por la cual, estos modelos de representación se generalizan, a lo largo de distancias enormes y entre los pueblos más diversos, es porque son conocimientos que surgen ligados a los tejidos. Hasta donde sabemos, casi la totalidad de los indígenas tejían en algodón o diversas fibras, con lo cual, una vez iniciado el proceso de guardar informaciones todos ellos contaron con una base simple y sólida para fortalecer el proceso de recopilación de datos, y guardarlos con precisión. Muchos son los ejemplos de cómputos realizados con mecates, al estilo de los quipus suramericanos. En el arte de tejer surgen conocimientos matemáticos que les permitieron guardar informaciones muy variadas: calendáricas, astronómicas, culturales, entre otras, que luego eran expresadas como una visión de mundo, una cosmogonía.

  16. 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

  17. From 9 to 12 and Finally 8: how Many Planets are around the Sun? (Spanish Title: De 9 a 12 y Finalmente 8: ¿Cuántos Planetas Hay Alrededor del Sol?) De 9 a 12 e Finalmente 8: Quantos Planetas Existem AO Redor do Sol?

    Science.gov (United States)

    Tancredi, Gonzalo

    2007-12-01

    The International Astronomical Union, the organization that groups together the professional astronomers over the world, has recently adopted a historical definition: What is a planet in the Solar System? Changing 76 years of tradition, our Solar System has now 8 planets and an increasing number of a new category of bodies named "dwarf planets", among them is the former planet Pluto. In this article we present the reasons that support the resolution and we describe the participation of the Latin-American astronomers in the process to adopt it. La Unión Astronómica Internacional, la organización que agrupa a los astrónomos profesionales del planeta, acaba de adoptar una definición histórica: ¿Qué es un planeta en nuestro Sistema Solar? Cambiando 76 años de tradición, según esta definición, nuestro Sistema Solar cuenta con 8 planetas y una creciente cantidad de "planetas enanos", entre los que quedó incluido el hasta hace poco planeta Plutón. En el presente artículo se presentarán los argumentos que fundamentan esta resolución y la participación que han tenido los astrónomos latinoamericanos en la adopción de la misma. A União Astronômica Internacional, a organização que agrupa os astrônomos profissionais do planeta, acaba de adotar uma definição histórica: O que é um planeta em nosso Sistema Solar? Mudando 76 anos de tradição, segundo esta definição, nosso Sistema Solar conta com 8 planetas e uma crescente quantidade de "planetas anões", entre os quais foi incluido o até há pouco planeta Plutão. No presente artigo serão apresentados os argumentos que fundamentam esta resolução e a participação que tiveram os astrônomos latino-americanos na adoção da mesma.

  18. 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

  19. 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)

  20. 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.

  1. 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

  2. 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

  3. 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

  4. 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.

  5. 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.

  6. 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.

  7. 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...

  8. 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.

  9. 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

  10. 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

  11. Estudio espectroscópico y fotométrico de candidatas a estrellas Herbig AeBe

    Science.gov (United States)

    Giuppone, C. A.; Rodón, J. A.; Yapura, O.; Yaryura, C. Y.

    A photometric study of the candidates to Herbig AeBe stars EM LKHA 108, NGC 6530 151 and NGC 6530 45 from the open cluster NGC 6530 was started. This study is part of a wider effort intended to confirm the membership to this class of these stars. Direct images were taken at Complejo Astronómico El Leoncito with the 215 cm telescope and filters B and V. The reduction to the Johnson UBV system was performed with the noao.imred package of IRAF, while the aperture photometry was accomplished with the digiphot.apphot package. The apparent magnitudes and colors obtained were, for EM LKHA 108: V=14.6, σV=1.1, (B-V)=1.0, σ(B-V)=0.1; for NGC 6530 151: V=11.8, σV=0.1, (B-V)=0.69, σ(B-V)=0.05; and for NGC 6530 45: V=7.2, σV=0.1, (B-V)=1.27, σ(B-V)=0.09. The spectroscopic study could not be performed yet due to technical difficulties in obtaining the spectra.

  12. Ruprecht 3: An old star cluster remnant?

    Science.gov (United States)

    Pavani, D. B.; Bica, E.; Ahumada, A. V.; Clariá, J. J.

    2003-02-01

    2MASS J and H photometry and integrated spectroscopy are employed to study the nature of the poorly populated compact concentration of stars Ruprecht 3, which was previously catalogued as an open cluster. The integrated spectrum remarkably resembles that of a moderately metal-rich globular cluster. The distribution of the object stars in the colour-magnitude diagram is compatible with that of a 1.5 +/- 0.5 Gyr open cluster or older, depending on whether the bluer stars are interpreted as turnoff stars or blue stragglers, respectively. We derive for the object a distance from the Sun dsun = 0.72 +0.04-0.03 kpc and a colour excess E(B-V) = 0.04. Although a globular cluster remnant cannot be ruled out, the integrated spectrum resemblance to that of a globular cluster probably reflects a stochastic effect owing to the few brighter stars. The structural and photometric properties of Ruprecht 3 are compatible with what would be expected for an intermediate-age open cluster remnant. Based on observations made at Complejo Astronómico El Leoncito, which is 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, Argentina.

  13. The Highly Polarized Open Cluster Trumpler 27

    Science.gov (United States)

    Feinstein, Carlos; Baume, Gustavo; Vazquez, Ruben; Niemela, Virpi; Cerruti, Miguel Angel

    2000-10-01

    We have carried out multicolor linear polarimetry (UBVRI) of the brightest stars in the area of the open cluster Trumpler 27. Our data show a high level of polarization in the stellar light with a considerable dispersion, from P=4% to P=9.5%. The polarization vectors of the cluster members appear to be aligned. Foreground polarization was estimated from the data of some nonmember objects, for which two different components were resolved: the first one associated with a dust cloud close to the Sun producing Pλmax=1.3% and θ=146°, and a second component, the main source of polarization for the cluster members, originating in another dust cloud, which polarizes the light in the direction of θ=29.5d. From a detailed analysis, we found that the two components have associated values EB-V0.75 for the other. Due the difference in the orientation of both polarization vectors, almost 90° (180° at the Stokes representation), the first cloud (θ~146°) depolarizes the light strongly polarized by the second one (θ~29.5d). Based on observations obtanined at Complejo Astronómico El Leoncito (CASLEO), operated under agreement between CONICET and the National Universities of La Plata, Córdoba, and San Juan, Argentina.

  14. VizieR Online Data Catalog: UBVRI polarization in Stock 16 (Feinstein+, 2003)

    Science.gov (United States)

    Feinstein, C.; Baume, G.; Vergne, M. M.; Vazquez, R. A.

    2003-08-01

    Polarimetric data for 27 stars in the region of Stock 16 cluster obtained using the Torino five-channel photopolarimeter attached to the 2.15 m telescope at the Complejo Astron'omico El Leoncito in San Juan, Argentina. The stellar identification (column 1) are given by Turner (1985ApJ...292..148T) and we also included 4 stars indicated as A, B, C, D, not observed by Turner. In table1.dat, for each star in all the filters (UBVRI) are given the polarization percentage average (P_lambda, column 2) and the position angle of the electric vector (theta_lambda, column 3) with their respective mean errors computed according to Maronna, Feinstein and Clocchiatti (1992A&A...260..525M). The polarimetric observations in the five filters were fitted in each star using Serkowski's law (Serkowski, 1973, in IAU Symp. 52, Interstellar Dust and Related Topics, ed. J. M. Greenberg H. C. van de Hults (Dordrech: Reidel), p. 145) in table2.dat. In columns 2 and 4 are listed the values obtained for Pλmax and lambdamax with their respective errors. The column 3 shows the unit weight error of the fit (sigma1), to quantify the departure of our data from the theoretical curve of Serkowski's law. In the column 5 is listed the dispersion of the position angle normalized by the average of the position angle errors (ɛ). (2 data files).

  15. BVI photometry and integrated spectroscopy of the very young open clusters Ruprecht 119, NGC 6318 and BH 245

    Science.gov (United States)

    Piatti, A. E.; Bica, E.; Clariá, J. J.

    2000-10-01

    We present CCD BVI observations obtained for stars in the fields of the unstudied or poorly studied open clusters Ruprecht 119, NGC 6318, and BH 245 projected close to the direction towards the Galactic centre. We measured V magnitude and B-V and V-I colours for about 600 stars reaching down to V ~ 19 mag. From the analysis of the colour magnitude diagrams, we confirmed the physical reality of the clusters and derived their reddening, distance and age for the first time. In addition, we obtained flux-calibrated integrated spectra in the range 3500-9200 Å for the cluster sample. Using the equivalent widths of the Balmer lines and comparing the cluster spectra with template spectra we derive both foreground reddening and age. The photometric and spectroscopic results reveal that the three studied objects are very young open clusters with ages ranging between 10 and 15 Myr, which have already undergone the HII region evolutionary phase and are dominated by the upper MS stars. The clusters, located between 1.1 kpc and 3.3 kpc from the Sun, are affected by different amounts of interstellar visual absorption (2.4 Complejo Astronómico El Leoncito, which is operated under agreement between the Consejo Nacional de Investigaciones Científicas y Técnics de la República Argentina and the National Universities of La Plata, Córdoba, and San Juan, Argentina.

  16. El cúmulo abierto NGC 6167 en la Asociación Ara OB1

    Science.gov (United States)

    Folatelli, G.; Morrell, N. I.; Barbá, R. H.

    We have carried out a spectrophotometric study of the central region of the open cluster NGC 6167. We were motivated to do so by the fact that this cluster could have had a main role in the star formation history of Ara OB1 Association (Arnal et al., 1987, A&A 174, 78), though it had not been thoroughly studied. Particularly, there was no previous research based on CCD data, and even the existence of the cluster itself had been discussed by some authors. By means of CCD photometry and intermediate resolution spectroscopy on images obtained at the Complejo Astronómico El Leoncito (CASLEO, San Juan) we have obtained B and V magnitudes down to V=19 in the central region of the cluster, along with spectral types and radial velocities for 85 stars. This information allowed us to determine for NGC 6167 a distance modulus of 10.5 ± 0.3 and a mean radial velocity of -39 ± 14 km s-1, which are in agreement with the values corresponding to the open cluster NGC 6193 and with the Ara OB1 Association as a whole. We discuss the role of NGC 6167 in the context of Ara OB1.

  17. Dating star clusters in the Small Magellanic Cloud by means of integrated spectra

    Science.gov (United States)

    Ahumada, A. V.; Clariá, J. J.; Bica, E.; Dutra, C. M.

    2002-10-01

    In this study flux-calibrated integrated spectra in the range (3600-6800) Å are presented for 16 concentrated star clusters in the Small Magellanic Cloud (SMC), approximately half of which constitute unstudied objects. We have estimated ages and foreground interstellar reddening values from the comparison of the line strengths and continuum distribution of the cluster spectra with those of template cluster spectra with known parameters. Most of the sample clusters are young blue clusters (6-50 Myr), while L 28, NGC 643 and L 114 are found to be intermediate-age clusters (1-6 Gyr). One well known SMC cluster (NGC 416) was observed for comparison purposes. The sample includes clusters in the surroundings and main body of the SMC, and the derived foreground reddening values are in the range 0.00 B-V) Complejo Astronómico El Leoncito, which is 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, Argentina.

  18. Photometric and spectroscopic study of low mass embedded star clusters in reflection nebulae

    Science.gov (United States)

    Soares, J. B.; Bica, E.; Ahumada, A. V.; Clariá, J. J.

    2005-02-01

    An analysis of the candidate embedded stellar systems in the reflection nebulae vdBH-RN 26, vdBH-RN} 38, vdBH-RN} 53a, GGD 20, ESO 95-RN 18 and NGC 6595 is presented. Optical spectroscopic data from CASLEO (Argentina) in conjunction with near infrared photometry from the 2MASS Point Source Catalogue were employed. The analysis is based on source surface density, colour-colour and colour-magnitude diagrams together with theoretical pre-main sequence isochrones. We take into account the field population affecting the analysis by carrying out a statistical subtraction. The fundamental parameters for the stellar systems were derived. The resulting ages are in the range 1-4 Myr and the objects are dominated by pre-main sequence stars. The observed masses locked in the clusters are less than 25 M⊙. The studied systems have no stars of spectral types earlier than B, indicating that star clusters do not necessarily evolve through an HII region phase. The relatively small locked mass combined with the fact that they are not numerous in catalogues suggests that these low mass clusters are not important donors of stars to the field populations. Based on observations made at Complejo Astronómico El Leoncito, which is 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, Argentina.

  19. Reddening and age for 13 southern Galactic open clusters determined from integrated spectra

    Science.gov (United States)

    Ahumada, A. V.; Clariá, J. J.; Bica, E.; Dutra, C. M.; Torres, M. C.

    2001-10-01

    In this study we present flux-calibrated integrated spectra in the range 3800-6800 Å for 13 concentrated open clusters with Galactic longitudes between 219deg and 316deg, nine of which have not been previously studied. Using the equivalent widths of the Balmer lines and comparing the cluster spectra with template spectra of Magellanic Clouds and Galactic star clusters with known parameters, we derive both foreground interstellar reddening values and age. For nine clusters these two parameters have been determined for the first time, while for the rest of the sample the results show good agreement with previous studies. The present analysis indicates four very young (Hogg 11, NGC 5606, vdB-RN 80 and Pismis 17), seven moderately young (ESO 429-SC13, Hogg 3, Hogg 12, Haffner 7, BH 87, NGC 2368 and Bochum 12) and two intermediate-age (Berkeley 75 and NGC 2635) open clusters. The derived foreground interstellar reddening values are in the range 0.00 B-V) Complejo Astronómico El Leoncito, which is 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, Argentina.

  20. 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.

  1. Near infrared photometric and optical spectroscopic study of 22 low mass star clusters embedded in nebulae

    Science.gov (United States)

    Soares, J. B.; Bica, E.; Ahumada, A. V.; Clariá, J. J.

    2008-02-01

    Aims:Among the star clusters in the Galaxy, those embedded in nebulae represent the youngest group, which has only recently been explored. The analysis of a sample of 22 candidate embedded stellar systems in reflection nebulae and/or HII environments is presented. Methods: We employed optical spectroscopic observations of stars in the directions of the clusters carried out at CASLEO (Argentina) together with near infrared photometry from the 2MASS catalogue. Our analysis is based on source surface density, colour-colour diagrams and on theoretical pre-main sequence isochrones. We take into account the field star contamination by carrying out a statistical subtraction. Results: The studied objects have the characteristics of low mass systems. We derive their fundamental parameters. Most of the cluster ages are younger than 2 Myr. The studied embedded stellar systems in reflection nebulae and/or HII region complexes do not have stars of spectral types earlier than B. The total stellar masses locked in the clusters are in the range 20-220 M⊙. They are found to be gravitationally unstable and are expected to dissolve in a timescale of a few Myr. Based on observations made at Complejo Astronómico El Leoncito, which is 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, Argentina.

  2. The NaI D resonance lines in main-sequence late-type stars

    Science.gov (United States)

    Díaz, Rodrigo F.; Cincunegui, Carolina; Mauas, Pablo J. D.

    2007-07-01

    We study the sodium D lines (D1: 5895.92Å D2: 5889.95Å) in late-type dwarf stars. The stars have spectral types between F6 and M5.5 (B - V between 0.457 and 1.807) and metallicity between [Fe/H] = -0.82 and 0.6. We obtained medium-resolution echelle spectra using the 2.15-m telescope at the Argentinian observatory Complejo Astronómico El Leoncito (CASLEO). The observations have been performed periodically since 1999. The spectra were calibrated in wavelength and in flux. A definition of the pseudo-continuum level is found for all our observations. We also define a continuum level for calibration purposes. The equivalent width of the D lines is computed in detail for all our spectra and related to the colour index (B - V) of the stars. When possible, we perform a careful comparison with previous studies. Finally, we construct a spectral index (R'D) as the ratio between the flux in the D lines and the bolometric flux. We find that, once corrected for the photospheric contribution, this index can be used as a chromospheric activity indicator in stars with a high level of activity. Additionally, we find that combining some of our results, we obtain a method to calibrate in flux stars of unknown colour.

  3. 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.

  4. Central stars of planetary nebulae. II. New OB-type and emission-line stars

    Science.gov (United States)

    Weidmann, W. A.; Gamen, R.

    2011-07-01

    Context. There are more than 3000 confirmed and probably known Galactic planetary nebulae (PNe), but central star spectroscopic information is available for only 13% of them. Aims: We have undertaken a spectroscopic survey of the central stars in PNe to identify their spectral types. Methods: We performed spectroscopic observations at low resolution with the 2-m telescope at CASLEO, Argentina. Results: We present the spectra of 46 central stars of PNe, most of them are OB-type and emission-line stars. Based on data collected at the Complejo Astronómico El Leoncito (CASLEO), which is operated under agreement between the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina y Universidades Nacionales de La Plata, Córdoba y San Juan, Argentina.The reduced spectra (FITS files) are available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/531/A172

  5. Central stars of planetary nebulae: New spectral classifications and catalogue

    Science.gov (United States)

    Weidmann, W. A.; Gamen, R.

    2011-02-01

    Context. There are more than 3000 confirmed and probable known Galactic planetary nebulae (PNe), but central star spectroscopic information is available for only 13% of them. Aims: We undertook a spectroscopic survey of central stars of PNe at low resolution and compiled a large list of central stars for which information was dispersed in the literature. Methods: We observed 45 PNs using the 2.15 m telescope at Casleo, Argentina. Results: We present a catalogue of 492 confirmed and probable CSPN and provide a preliminary spectral classification for 45 central star of PNe. This revises previous values of the proportion of CSPN with atmospheres poor in hydrogen in at least 30% of cases and provide statistical information that allows us to infer the origin of H-poor stars. Based on data collected at the Complejo Astronómico El Leoncito (CASLEO), which is operated under agreement between the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina y Universidades Nacionales de La Plata, Córdoba y San Juan, Argentina.

  6. Fast numerics for the spin orbit equation with realistic tidal dissipation and constant eccentricity

    Science.gov (United States)

    Bartuccelli, Michele; Deane, Jonathan; Gentile, Guido

    2017-03-01

    We present an algorithm for the rapid numerical integration of a time-periodic ODE with a small dissipation term that is C^1 in the velocity. Such an ODE arises as a model of spin-orbit coupling in a star/planet system, and the motivation for devising a fast algorithm for its solution comes from the desire to estimate probability of capture in various solutions, via Monte Carlo simulation: the integration times are very long, since we are interested in phenomena occurring on timescales of the order of 10^6 -10^7 years. The proposed algorithm is based on the high-order Euler method which was described in Bartuccelli et al. (Celest Mech Dyn Astron 121(3):233-260, 2015), and it requires computer algebra to set up the code for its implementation. The payoff is an overall increase in speed by a factor of about 7.5 compared to standard numerical methods. Means for accelerating the purely numerical computation are also discussed.

  7. Contribution of the surface layer to the seeing at San Pedro Mártir: simultaneous microthermal and dimm measurements

    Directory of Open Access Journals (Sweden)

    L. J. Sánchez

    2003-01-01

    Full Text Available Reportamos medidas de la contribuci on de la capa super cial al seeing en el Observatorio Astron omico Nacional de San Pedro M artir (OAN{SPM. Utilizamos un m astil instrumentado con sensores de temperatura microdiferenciales localizados en 7 niveles para medir la constante de estructura del indice de refracci on C2 n en los primeros 15-m. El par ametro de distorsi on de la imagen (llamado com unmente seeing integrado se determin o utilizando un Monitor Diferencial de Movimiento de Imagen durante 23 noches. Se encontr o una estad stica log{normal con valores promedio de 0.9800 y de mediana 0.8400. La contribuci on de la capa super cial (2.3 a 15-m a la turbulencia optica total tiene un valor promedio de 16%, lo cual corresponde a una degradaci on de 10% del seeing total. Estos valores son similares a los encontrados en otros observatorios en el mundo, lo que sugiere que la presencia de arboles en el sitio del OAN{SPM no afecta de manera considerable el seeing debido a la capa super cial. Se requieren m as estudios para con rmar esta tendencia.

  8. 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.

  9. SPECKLE INTERFEROMETRY AT THE OBSERVATORIO ASTRONÓMICO NACIONAL. I

    Directory of Open Access Journals (Sweden)

    V. G. Orlov

    2009-01-01

    Full Text Available Presentamos los resultados de mediciones mediante interferometría de motas de algunas estrellas binarias, llevadas a cabo en noviembre de 2008 en el telescopio de 1 m del Observatorio Astronómico Nacional en Tonantzintla (Puebla, México. Los datos consisten de 175 ángulos de posición y separaciones medidas para 163 sistemas. Las separaciones medidas están comprendidas entre 0.1500 y 4.0000. La magnitud máxima de las componentes más brillantes es igual a 9.32. El error medio en la medición de las separaciones es de 0.0300, y en los ángulos de posición, de 1 grado. La mayor parte de los ángulos de posición tienen la usual ambigüedad de 180 grados, y algunos de ellos se corrigieron comparándolos con observaciones hechas por otros autores.

  10. 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.

  11. Electron Density Measurements in the National Spherical Torus Experiment Detached Divertor Region Using Stark Broadening of Deuterium Infrared Paschen Emission Lines

    Energy Technology Data Exchange (ETDEWEB)

    Soukhanovskii, V A; Johnson, D W; Kaita, R; Roquemore, A L

    2007-04-27

    Spatially resolved measurements of deuterium Balmer and Paschen line emission have been performed in the divertor region of the National Spherical Torus Experiment using a commercial 0.5 m Czerny-Turner spectrometer. While the Balmer emission lines, Balmer and Paschen continua in the ultraviolet and visible regions have been extensively used for tokamak divertor plasma temperature and density measurements, the diagnostic potential of infrared Paschen lines has been largely overlooked. We analyze Stark broadening of the lines corresponding to 2-n and 3-m transitions with principle quantum numbers n = 7-12 and m = 10-12 using recent Model Microfield Method calculations (C. Stehle and R. Hutcheon, Astron. Astrophys. Supl. Ser. 140, 93 (1999)). Densities in the range (5-50) x 10{sup 19} m{sup -3} are obtained in the recombining inner divertor plasma in 2-6 MW NBI H-mode discharges. The measured Paschen line profiles show good sensitivity to Stark effects, and low sensitivity to instrumental and Doppler broadening. The lines are situated in the near-infrared wavelength domain, where optical signal extraction schemes for harsh nuclear environments are practically realizable, and where a recombining divertor plasma is optically thin. These properties make them an attractive recombining divertor density diagnostic for a burning plasma experiment.

  12. Stability of triangular equilibrium points in the elliptic restricted problem of three bodies with radiating and triaxial primaries

    Science.gov (United States)

    Narayan, A.; Usha, T.

    2014-05-01

    This paper studies the stability of infinitesimal motions about the triangular equilibrium points in the elliptic restricted three body problem assuming bigger primary as a source of radiation and the smaller one a triaxial rigid body. The perturbation technique developed by Bennet (Icarus 4:177, 1965b) has been used for determination of characteristic exponents. This technique is based on Floquet's Theory for determination of characteristic exponents in the system with periodic coefficients. The results of the study are analytical and numerical expressions are simulated for the transition curves bounding the region of stability in the μ-e plane, accurate to O( e 2). The unstable region is found to be divided into three parts. The effect of radiation parameter is significant. For small values of e, the results are in favor with the numerical analysis of Danby (Astron. J. 69:166, 1964), Bennet (Icarus 4:177, 1965b), Alfriend and Rand (AIAA J. 6:1024, 1969). The effect of radiation pressure is significant than the oblateness and triaxiality of the primaries.

  13. 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...

  14. Movimientos Propios y Determinacion de Pertenencia en el Cumulo Abierto NGC 2587

    Science.gov (United States)

    Bustos Fierro, I. H.; Calderón, J. H.

    The main aim of this work is the development and testing of a method for the astrometric measurement of photographic plates using a CCD camera as a digitizing device. This method is useful for the measurement of first epoch positions from more than 3000 plates in the vault of the Observatorio Astronómico de Córdoba, most of them more than 80 years old, in order to determine accurate proper motions. The developed method is applied to a Carte du Ciel plate in order to obtain positions of 4172 stars at epoch 1917.13 with errors about 0.20arcsec. By combining these positions with USNO-B1.0 and UCAC2 proper motions with accuracies around 2mas/year were determined for 4061 stars in a square field 2deg sided contaning the open clustes NGC 2587. Projected stellar density is studied in order to locate the cluster. Membership probabilities were determined from the proper motions by means of a non-parametric method and Monte Carlo simulations. 31 probable members were identified within 15arcmin around the projected overdensity asumed as the cluster, 22 of them within 10arcmin.

  15. Searching for the earliest galaxies in the 21cm forest

    Institute of Scientific and Technical Information of China (English)

    Andrea; FERRARA; Francisco; S.; KITAURA

    2010-01-01

    We use a model developed by Xu,Ferrara,and Chen(Mon Not Roy Astron Soc,submitted) to compute the 21 cm line absorption signatures imprinted by star-forming dwarf galaxies(DGs) and starless minihalos(MHs). The method,based on a statistical comparison of the equivalent width(W ν ) distribution and flux correlation function,allows us to derive a simple selection criteria for candidate DGs at very high(z ≤ 8) redshift. We find that ≈18% of the total number of DGs along a line of sight to a target radio source(GRB or quasar) can be identified by the condition W ν<0; these objects correspond to the high-mass tail of the DG distribution at high redshift,and are embedded in large HII regions. The criterion W ν>0.37 kHz instead selects ≈11% of MHs. Selected candidate DGs could later be re-observed in the near-IR by the JWST with high efficiency,thus providing a direct probe of the most likely reionization sources.

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

    Science.gov (United States)

    Cuevas, Salvador; Langarica, Rosalia; Watson, Alan M.; Fuentes-Fernández, Jorge; Ángeles, Fernando; Farah, Alejandro S.; Figueroa, Liliana; Becerra-Godínez, Rosa L.; Chapa, Oscar; Román-Zúñiga, Carlos G.; Quiróz, Fernando; Tejada, Carlos; Álvarez-Núñez, Luis C.; Ruz, Jaime; Tinoco, Silvio J.

    2016-08-01

    COATLI is a new instrument and telescope that will provide 0.3 arcsec FWHM images from 550 to 920 nm over a large fraction of the sky. It consists of a robotic 50-cm telescope with a diffraction-limited imager. The imager has a steering mirror for fast guiding, a blue channel using an EMCCD from 400 to 550 nm to measure image motion, a red channel using a standard CCD from 550 to 920 nm, and an active optics system based on a deformable mirror to compensate static aberrations in the red channel. Since the telescope is small, fast guiding will provide diffraction-limited image quality in the red channel over a large fraction of the sky, even in relatively poor seeing. The COATLI telescope will be installed at the Observatorio Astronómico Nacional in Sierra San Pedro Mártir, Baja California, México, in 2016 and will initially operate with a simple interim imager. The definitive COATLI instrument will be installed in 2017. In this work we present the general optomechanical and control electronics design of COATLI.

  17. Telescopio Solar en Hα (HASTA)

    Science.gov (United States)

    Fernández Borda, R.; Francile, C.; Bagala, G.; Bauer, O.; Haerendel, G.; Rieger, E.; Rovira, M.

    El Telescopio Solar en Hα (Hα Solar Telescope for Argentina (-HASTA-) fue recientemente instalado en la Estación Astronómica de Altura Carlos Ulrrico Cesco (OAFA) en El Leoncito. Este instrumento estudiará la evolución de las fulguraciones solares desde tierra con alta resolución temporal y espacial. HASTA es un telescopio refractor de 110 mm con una distancia focal de 165 cm, un filtro Lyot sintonizable (±1Å) con un ancho de banda de 0.3 Å y una cámara CCD de alta resolución (1280×1024 pixels). Todo el conjunto es controlado en forma remota por una PC, la cual además adquiere datos del Sistema de Posicionamiento Global (GPS) y de la estación meteorológica. Diseñado para detectar fulguraciones, el instrumento trabaja en dos modos (patrullaje y fulguración) con una resolución espacial de 1.5 arcseg por pixel y una resolución temporal de 2 seg. HASTA comenzó a operar en Mayo de 1998 y, junto con otros tres instrumentos solares, que se están instalando o se instalaron, harán de El Leoncito un polo de observación solar importante en el Hemisferio Sur.

  18. 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.

  19. 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.

  20. WHAT CAN WE LEARN ABOUT THE KINEMATICS OF BRIGHT EXTRAGALACTIC PLANETARY NEBULAE?

    Directory of Open Access Journals (Sweden)

    M. G. Richer

    2009-01-01

    Full Text Available Presentamos espectroscop a de alta resoluci n en las l neas de [O III]-5007 y H de nebulosas planetarias (NPs brillantes en el bulbo de nuestra V a L ctea as como las galaxias enanas M32, Fornax, Sagittarius y NGC 6822, obtenida en el Observatorio Astron mico Nacional en la Sierra San Pedro M rtir con el espectr grafo Manchester echelle. Utilizamos las observaciones profundas de las NPs gal cticas para determinar la informaci n cinem tica con able que puede obtenerse mediante las observaciones mucho menos profundas de las NPs extragal cticas observadas en la l nea de [O III]-5007. Encontramos que la anchura intr nseca de las l neas en [O III]-5007 y H son similares, que la anchura no depende de la relaci n se al a ruido (dentro del intervalo cubierto por la muestra, y que las desviaciones respecto a una forma gausiana son peque as. Concluimos que la anchura de la l nea de [O III]-5007 en NPs extragal cticas re eja de manera el la cinem ica de la mayor a de la masa de la c scara ionizada.

  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. Electron impact excitation of N$^{3+}$ using the B-spline R-matrix method: Limitations due to the target structure description and the size of the close-coupling expansion

    CERN Document Server

    Fernández-Menchero, L; Bartschat, K

    2016-01-01

    There are major discrepancies between recent ICFT (Intermediate Coupling Frame Transformation) and DARC (Dirac Atomic R-matrix Code) calculations (Fern\\'andez-Menchero et al. 2014, Astron. Astroph. 566 A104, Aggarwal et al. 2016 Mon. Not. R Astr. Soc. 461 3997) regarding electron impact excitation rates for transitions in several Be-like ions, as well as claims that DARC calculations are much more accurate and the ICFT results might even be wrong. To resolve possible reasons for these discrepancies and to estimate the accuracy of the various results, we carried out independent B-Spline R-Matrix (BSR) calculations for electron-impact excitation of the Be-like ion N$^{3+}$. Our close-coupling expansions contain the same target states (238 levels overall) as the previous ICFT and DARC calculations, but the representation of the target wave functions is completely different. We find close agreement among all calculations for the strong transitions between low-lying states, whereas there remain serious discrepanci...

  3. 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.

  4. 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

  5. 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.

  6. 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.

  7. 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

  8. The composition of transiting giant extrasolar planets

    Energy Technology Data Exchange (ETDEWEB)

    Guillot, T [Laboratoire Cassiopee, CNRS UMR 6202, Observatoire de la Cote d' Azur, BP4229, 06304 Nice Cedex 4 (France)], E-mail: guillot@obs-nice.fr

    2008-08-15

    In principle, the combined measurements of the mass and radius of a giant exoplanet allow one to determine the relative fraction of hydrogen and helium and of heavy elements in the planet. However, uncertainties on the underlying physics imply that some known transiting planets appear anomalously large, and this generally prevents any firm conclusion when a planet is considered on an individual basis. On the basis of a sample of nine transiting planets known at that time, Guillot et al (1996 Astron. Astrophys.453 L21) concluded that all planets could be explained with the same set of hypotheses, either by large but plausible modifications of the equations of state, opacities, or by the addition of an energy source, probably related to the dissipation of kinetic energy by tides. On this basis, they concluded that the amount of heavy elements in close-in giant planets is correlated with the metallicity of the parent star. Furthermore, they showed that planets around metal-rich stars can possess large amounts of heavy elements, up to 100 Earth masses. These results are confirmed by studying the present sample of 18 transiting planets with masses between that of Saturn and twice the mass of Jupiter.

  9. 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

  10. 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.

  11. THE CLIMATE OF NORTHERN CHILE: MEAN STATE, VARIABILITY AND TRENDS

    Directory of Open Access Journals (Sweden)

    R. D. Garreaud

    2011-01-01

    Full Text Available Este manuscrito documenta las características principales del clima del norte de Chile, lugar donde se ubican, y donde se proyecta, la instalación de varios observatorios astronómicos. Primeramente se provee de una descripción del clima regional a una escala espacial amplia, donde se describe la importancia relativa de la celda de Hadley, del Monsón Sud-Americano, y perturbaciones extra-tropicales en dar forma al estado promedio de la temperatura, precipitación y vientos en la región. Entonces, se describen los efectos de la Oscilación del Sur-El Niño para producir algún nivel de variabilidad inter-anual en el clima del norte de Chile. Se concluye este trabajo, basándose en lo expuesto en estudios recientes, con un resumen de las tendencias observadas y proyecciones en el cambio climático para lo que resta del siglo XXI.

  12. De la astroarqueología a la astronomía cultural

    Directory of Open Access Journals (Sweden)

    Iwaniszewski, Stanislaw

    1994-12-01

    Full Text Available The author outlines a sketch of the development of the study of astronomical and calendrical practices in its sociocultural context during the last thirty years. This study has gone through many changes and these stages may be symbolized by the names of astroarchaeology, megalithic astronomy, archaeoastronomy, ethnoastronomy and cultural astronomy. The author describes this evolution, and the present state of this discipline and then gives a bibliography on the subject in order to promote such research in Spain.

    El autor bosqueja las relaciones entre el estudio de las prácticas calendáricas y astronómicas y el contexto sociocultural al que corresponden durante los últimos treinta años. Los diversos cambios experimentados pueden simbolizarse en los nombres de la astroarqueología. la astronomía megalítica, la arqueoastronomía. la etnoastronomía y la astronomía cultural. El autor describe, además, el estado actual de esta disciplina y proporciona una amplia bibliografía sobre el tema con fines de promover la investigación en España.

  13. 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.

  14. A PHOTOMETRIC AND SPECTROSCOPIC EVALUATION OF THE SITE AT TONANTZINTLA OBSERVATORY

    Directory of Open Access Journals (Sweden)

    H. M. Hernández-Toledo

    2010-01-01

    Full Text Available Se presenta una evaluaci n sobre la calidad del cielo en el Observatorio Astron mico Nacional de Tonantzintla mediante la calibraci n fotom trica de un conjunto de estrellas est ndar en M67 en las bandas B, V , R e I del sistema Johnson-Cousins y la observaci n del cielo a diferentes distancias cenitales con el espectr grafo Boller & Chivens. El brillo del cielo se estim (a a partir de las observaciones CCD al c mulo M67 y (b utilizando un m todo visual en direcci n de estrellas de magnitud conocida. Se obtuvo un valor de 18:5 +- 0:6 mag arcsec-2. La curva de extinci n atmosf rica promedio presenta un comportamiento intermedio entre la observada para el OAN-San Pedro M rtir y la asociada a actividad volc nica. Los espectros del cielo en el OAN-Tonantzintla permiten identi car l neas asociadas a l mparas de HgI y NaI a baja y alta presi n. Nuestros resultados permiten justi car la actualizaci n y compra de nuevo equipamiento para convertir al OAN-Tonantzintla en el Laboratorio para la Ense~nanza de la Astronom a Observacional.

  15. Stellar Multiplicity of the Open Cluster ASCC 113

    Science.gov (United States)

    Guerrero, C. A.; Orlov, V. G.; Monroy-Rodríguez, M. A.; Voitsekhovich, V. V.

    2014-02-01

    We present a high angular resolution survey for binary and multiple stars in the Galactic open cluster ASCC 113. Our observations were conducted on the 2.1 m telescope of the Observatorio Astronómico Nacional, Sierra San Pedro Mártir, México. Combining our results with data taken from the literature, we found a ratio of the number of single to binary stars to be 27:7 for the most probable members, so the multiplicity fraction for this cluster is 20.6% ± 3%. We also observed field stars in the vicinity of the cluster and estimated a ratio of multiplicities to be 125:27:4:1:0:0:0:1 (between one and eight companions), equivalent to a multiplicity fraction of 20.9% ± 1%. We estimated the number of undetected companions in our sample to be very small. Comparing the multiplicity frequency of the cluster with the frequency of the field, we concluded that they are statistically indistinguishable from each other. We provide a brief review on the topic of stellar multiplicity in open clusters.

  16. 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.

  17. 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...

  18. VizieR Online Data Catalog: MASTER polarization observations (Pruzhinskaya+, 2014)

    Science.gov (United States)

    Pruzhinskaya, M. V.; Krushinsky, V. V.; Lipunova, G. V.; Gorbovskoy, E. S.; Balanutsa, P. V.; Kuznetsov, A. S.; Denisenko, D. V.; Kornilov, V. G.; Tyurina, N. V.; Lipunov, V. M.; Tlatov, A. G.; Parkhomenko, A. V.; Budnev, N. M.; Yazev, S. A.; Ivanov, K. I.; Gress, O. A.; Yurkov, V. V.; Gabovich, A. V.; Sergienko, Yu. P.; Sinyakov, E. V.

    2014-07-01

    We present results of optical polarization observations performed with the MASTER robotic net (Lipunov et al., 2004AN....325..580L, 2010, Advances in Astronomy, article id. 349171, 1; Kornilov et al., 2012, Exp. Astron., 33, p. 173) for three types of objects: gamma-ray bursts, supernovae, and blazars. For the Swift gamma-ray bursts GRB100906A, GRB110422A, GRB121011A, polarization observations were obtained during very early stages of optical emission. For GRB100906A it was the first prompt optical polarization observation in the world. Photometry in polarizers is presented for Type Ia Supernova 2012bh during 20 days, starting on March 27, 2012. We find that the linear polarization of SN 2012bh at the early stage of the envelope expansion was less than 3%. Polarization measurements for the blazars OC 457, 3C 454.3, QSO B1215+303, 87GB 165943.2+395846 at single nights are presented. We infer the degree of the linear polarization and polarization angle. The blazars OC 457 and 3C 454.3 were observed during their periods of activity. The results show that MASTER is able to measure substantially polarized light; at the same time it is not suitable for determining weak polarization (less than 5%) of dim objects (fainter than 16m). Polarimetric observations of the optical emission from gamma-ray bursts and supernovae are necessary to investigate the nature of these transient objects. (3 data files).

  19. 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 ...

  20. 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...

  1. Recalibrated turbulence profiles at San Pedro Mártir

    Directory of Open Access Journals (Sweden)

    R. Avila

    2011-01-01

    Full Text Available La calibración de perfiles de turbulencia óptica (C2N medidos con el método SCIDAR generalizado ha sido recientemente revisada y corregida por Avila & Cuevas (2009. Basándonos en ese trabajo, aquí presentamos la corrección de todos los perfiles de C2N medidos con el SCIDAR generalizado en el Observatorio Astronómico Nacional de San Pedro Mártir. El perfil de C2N mediano corregido conserva su estructura vertical general. El cociente promediado en altura de la mediana de los valores de C2N corregidos sobre la mediana de los valores no corregidos es igual a 0.87. La mediana del seeing corregido en el sitio es 0. ′′ 68 ± 0. ′′ 03, 4.2% menor que la mediana no corregida. Las medianas del seeing producido por turbulencia en los dos primeros kilómetros de altura sobre los telescopios de 1.5 m y 2.1 m de diámetro decrecen en un 15.8% y 13.6%, respectivamente. El ángulo isoplan ático corregido tiene una mediana de 1. ′′ 96 ± 0. ′′ 04.

  2. 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.

  3. RR Lyrae Search and Stellar Populations Study in Canis Major: Preliminary Results

    Directory of Open Access Journals (Sweden)

    C. E. Mateu

    2006-01-01

    Full Text Available Se presentan los resultados preliminares de un estudio de poblaciones estelares para la búsqueda de estrellas RR Lyrae, centrado en la sobredensidad de Can Mayor, sobre un área de 8:35 gd2 en el cielo. Las observaciones fueron hechas empleando los filtros R y V, con la cámara QUEST instalada en el telescopio Jürgen Stock de 1-m, ubicado en el Observatorio Astronómico Nacional de Venezuela. El diagrama de Hess resultante muestra una posible, pero tenue, rama de las gigantes rojas y no se observa en forma evidente una rama horizontal, concentración roja o final de la secuencia principal. Luego de una búsqueda fotométrica multi-época, 6 RR Lyrae fueron confirmadas con observaciones adicionales obtenidas a través de los telescopios de 1.0-m y 1.3-m del consorcio SMARTS en CTIO. De dichas RR Lyrae conformadas, 5 tienen distancias heliocéntricas entre 5 y 7 kpc. La confirmación de su asociación con el sistema de Can Mayor espera por un estudio de sus velocidades radiales.

  4. SPM-Twin Telescopes: Project Overview

    Directory of Open Access Journals (Sweden)

    J. Jesús González

    2007-01-01

    Full Text Available Se presenta el Proyecto de los Telescopios Gemelos en SPM. Esta es una iniciativa internacional que consiste en un par de telescopios de 6.5-m en el Observatorio Astron mico Nacional en San Pedro M rtir (SPM cuyo fin es el de proporcionar una plataforma flexible y altamente competitiva para nuevos descubrimientos. El proyecto se enfoca a nichos cient ficos t cnicamente dif ciles de resolver con los telescopios de mayor apertura existentes o en construcci n, y al mismo tiempo explota la superioridad del sitio de SPM. La pareja de telescopios que constituyen el proyecto se basan en el concepto comprobado y altamente eficiente del telescopio Magallanes, pero cada uno bajo una diferente optimizaci n, con el prop sito de cubrir dos aspectos complementarios, y a la vez mutuamente excluyentes: (a el ?Telescopio de Campo Est ndar? (SFT abarcar a un campo visual de 15 −30 , capaz de observar desde el ptico hasta el infrarrojo t rmico (0.4 − 24 m y estar a preparado para ptica adaptiva, y (b el ?Telescopio de Gran Campo? (WFT con campo visual de 1.5◦ o mayor, capaz de realizar espectroscop a de objetos m ltiples, espectroscop a de unidad de campo integral (IFU, y potencialmente tambi n obtener im genes en banda angosta; la espectroscop a en el WFT se extender a desde 0.36 a 1.8 m y contendr a varios miles de fibras

  5. 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...

  6. 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...

  7. 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.

  8. The Kinematics of the Permitted C ii λ6578 Line in a Large Sample of Planetary Nebulae

    Science.gov (United States)

    Richer, Michael G.; Suárez, Genaro; López, José Alberto; García Díaz, María Teresa

    2017-03-01

    We present spectroscopic observations of the C ii λ6578 permitted line for 83 lines of sight in 76 planetary nebulae at high spectral resolution, most of them obtained with the Manchester Echelle Spectrograph on the 2.1 m telescope at the Observatorio Astronómico Nacional on the Sierra San Pedro Mártir. We study the kinematics of the C ii λ6578 permitted line with respect to other permitted and collisionally excited lines. Statistically, we find that the kinematics of the C ii λ6578 line are not those expected if this line arises from the recombination of C2+ ions or the fluorescence of C+ ions in ionization equilibrium in a chemically homogeneous nebular plasma, but instead its kinematics are those appropriate for a volume more internal than expected. The planetary nebulae in this sample have well-defined morphology and are restricted to a limited range in Hα line widths (no large values) compared to their counterparts in the Milky Way bulge; both these features could be interpreted as the result of young nebular shells, an inference that is also supported by nebular modeling. Concerning the long-standing discrepancy between chemical abundances inferred from permitted and collisionally excited emission lines in photoionized nebulae, our results imply that multiple plasma components occur commonly in planetary nebulae.

  9. Successful model for cooperative student learning centers in physics and astronomy

    Science.gov (United States)

    Bieniek, Ronald J.; Johnson, John A.

    2003-04-01

    We have established successful problem-based learning centers for introductory courses in physics [1] and astronomy [2] that fully implement the Seven Principles of Good Practice in Undergraduate Education [3] without increased demand on faculty time. Large percentages of students at our two institutions voluntarily utilize these learning venues. Course instructors guide self-forming groups of students to mastery of technical concepts and skills, building greater student self-confidence through direct interaction and feedback. The approach's immediacy helps students recognize ambiguities in their understanding, thereby increasing impact at teachable moments. Underperforming students are assisted along side students who wish to hone their skills. The format also facilitates racial and gender mixing within learning center camaraderie. Specific pedagogical and operational techniques for running learning centers will be presented. [1] http://www.umr.edu/ physics/plc [2] http://astron.berkeley.edu/talc.html [3] A.W. Chickering & Z.F. Gamson, Am. Assoc. Higher Ed. Bulletin, 1987, 39(7) 3-7.

  10. 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.

  11. 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...

  12. 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.

  13. Programas de aplicación de agrometeorología para docencia e investigación

    Directory of Open Access Journals (Sweden)

    Bombelli, Enrique

    2009-01-01

    Full Text Available Para el estudio de las Ciencias Meteorológicas y Climáticas aplicadas al agro, es necesario estimar procesos matemáticos y físicos para interpretar la interacción de los procesos atmosféricos y biológicos, los cuales se pueden automatizar haciendo énfasis en el análisis de los mismos. El presente trabajo tiene como objetivo mostrar las características de un software de aplicación utilizado para en la enseñanza de la Climatología Agrícola, que estima parámetros tales como: Radiación Astronómica y Global, diferentes metodologías de cálculo de la Evapotranspiración Potencial y el Balance Hidrológico Climático entre otros. El software Programas de aplicación de Agroclimatología, realizado en la Facultad de Agronomía de la Universidad de Buenos Aires, brinda al alumno un rápido manejo de resultados, con la posibilidad de realizar interpretaciones de distintas variables para diferentes localidades, de manera de poder visualizar y analizar los resultados que surgen de las distintas corridas.

  14. Study of the nature of dark matter in halos of dwarf galaxies

    Science.gov (United States)

    Karmakar, Pradip; Chattopadhyay, Tanuka; Chattopadhyay, Asis Kumar

    2015-08-01

    The kinematics of dwarf galaxies are strongly influenced by dark matter down to small galactocentric radii. So they are good candidates to investigate the nature of Dark Matter. In the present work we have carried out mass modeling of a number of recently observed dwarf galaxies Swaters et al. in Astron. Astrophys. 493:871, 2009. We have used a Navarro-Frenk-White (NFW) halo, Freeman disc along with a gaseous disc for modeling the observed rotation curves of those dwarf galaxies. For comparison we also used a Burkert halo, Freeman disc and gaseous disc. For both the scenario we have performed Kolmogorov-Smirnov (KS) test between the observed and predicted rotational velocity profiles. The tests are rejected for NFW halo almost in 50 per cent cases but they are accepted almost for all cases for Burkert halo, preferring a Burkert halo model generally for dwarf galaxies. The above results reveal a constant density core of dark matter (DM) in the halos of dwarf galaxies compared to a cuspy nature of NFW halo and a possible challenge to -CDM scenario for the nature of dark matter in most of the dwarf galaxies.

  15. Fokker-Planck-Rosenbluth-Type Equations for Self-gravitating Systems in 1PN Approximation

    CERN Document Server

    Ramos-Caro, Javier

    2008-01-01

    We present two formulations of Fokker-Planck-Rosenbluth-type (FPR) equations for many-particle self-gravitating systems, with first order relativistic corrections in the post-Newtonian approach (1PN). The first starts from a covariant Fokker-Planck equation for a simple gas, introduced recently by G. Chacon-Acosta and G. Kremer (Phys. Rev. E 76, 021201, 2007). The second derivation is based on the establishment of an 1PN-BBGKY hierarchy, developed systematically from the 1PN microscopic law of force and using the Klimontovich-Dupree (KD) method. We close the hierarchy by the introduction of a two-point correlation function that describes adequately the relaxation process. This picture reveals an aspect that is not considered in the first formulation: the contribution of ternary correlation patterns to the diffusion coefficients, as a consequence of the nature of 1PN interaction. Both formulations can be considered as a generalization of the equation derived by Rezania and Sobouti (Astron. Astrophys. 54, 1110-...

  16. 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.

  17. Optical-turbulence and wind profiles at san Pedro Mártin with g-scidar

    Directory of Open Access Journals (Sweden)

    R. Avila

    2007-01-01

    Full Text Available La turbulencia atmosférica puede ser caracterizada por el centelleo de las fuentes astronómicas. Se presenta una breve revisión de la física del centelleo débil y fuerte. El Sensor de Centelleo Multi-Apertura, MASS, utiliza las propiedades espaciales del centelleo producido por una estrella para reconstruir perfiles de turbulencia de baja resolución. Se presenta una descripción del instrumento combinado MASS-DIMM y se evalúa la precisión de este método. Se describe el experimento de remplazar la estrella por un planeta, ya que en ese caso se puede sensar la turbulencia a unos cuantos cientos de metros sobre el sitio. Sin embargo, de mayor importancia es medir la turbulencia en la vecindad inmediata de un telescopio o un monitor del sitio. En este caso, un medidor de centelleo lunar es el método a elegir. Un medidor de centelleo lunar, LuSci, está siendo desarrollado por el Observatorio Inter-Americano de Cerro Tololo (CTIO. Se presenta el nuevo método para interpretar sus datos y los resultados de las primeras pruebas

  18. The 2003 Nov 14 occultation by Titan of TYC 1343-1865-1. II. Analysis of light curves

    CERN Document Server

    Zalucha, A; Elliot, J L; Thomas-Osip, J; Hammel, H B; Dhillon, V S; Marsh, T R; Taylor, F W; Irwin, P G J

    2007-01-01

    We observed a stellar occultation by Titan on 2003 November 14 from La Palma Observatory using ULTRACAM with three Sloan filters: u', g', and i' (358, 487, and 758 nm, respectively). The occultation probed latitudes 2 degrees S and 1 degrees N during immersion and emersion, respectively. A prominent central flash was present in only the i' filter, indicating wavelength-dependent atmospheric extinction. We inverted the light curves to obtain six lower-limit temperature profiles between 335 and 485 km (0.04 and 0.003 mb) altitude. The i' profiles agreed with the temperature measured by the Huygens Atmospheric Structure Instrument [Fulchignoni, M. et al., 2005. Nature 438, 785-791] above 415 km (0.01 mb). The profiles obtained from different wavelength filters systematically diverge as altitude decreases, which implies significant extinction in the light curves. Applying an extinction model [Elliot, J.L., Young, L.A., 1992. Astron. J. 103, 991-1015] gave the altitudes of line of sight optical depth equal to unit...

  19. Análise de Estruturas Morfológicas da Cauda de Plasma do Cometa P/Halley

    Science.gov (United States)

    Voelzke, M. R.; Matsuura, O. T.

    1997-08-01

    permitiram determinar o instante de suas origens, ou seja, o instante em que supostamente a de sconexão teve lugar no núcleo. Assim, foram identificados 19 D.E.'s distintos. Aparentemente o plasma desconectado de um dado D.E. afasta-se com velocidade constante do núcleo cometário. Tal velocidade, contudo, varia enormemente de um D.E. para outro. Nove D.E.'s pré-periélicos apresentaram velocidade média Vc, corrigida dos efeitos de projeção, igual a (260 +- 87) km/s e dez pós-periélicos (130 +- 37) km/s. Esta assimetria de Vc em relação ao periélio pode ser devida ao modo assimétrico com que a componente radial da velocidade orbital do cometa se combina com a velocidade do vento solar no sistema de referência cometocêntrico. Os D.E.'s foram correlacionados com variações simultâneas de brilho, formação de jatos e outros fenômenos associados. Sua ocorrência é discutida no contexto dos modelos de reconexão magnética e de compressão dinâmica por vento solar exacerbado. - Brandt, J.C., Niedner, M.B.Jr. and Rahe, J., The International Halley Watch Atlas of Large-Scale Phenomena (printed by: Johnson Printing Co, Boulder, CO), University of Colorado-Boulder, 1992. - Celnik, W.E., Koczet, P., Schlosser, W., Schulz, R., Svejda, P. and Weissbauer, K., Astron. Astrophys. Suppl. Ser. 72, 89, 1988. - Delva, M., Schwingenschuh, K., Niedner, M.B.Jr. and Gringauz, K.I., Planet. Space Sci. 39, Number 5, 697, 1991. - Hyder, C.L., Brandt, J.C. and Roosen, R.G., Icarus 23, 601, 1974. - Jockers, K., Astron. Astrophys. Suppl. Ser. 62, 791, 1985. - Matsuura, O.T. and Voelzke, M.R., Rev. Mexicana Astron. Astrof. 21, 609, 1990. - Niedner, M.B.Jr. and Brandt, J.C., Astrophys. J. 234, 723, 1979. - Niedner, M.B.Jr. and Brandt, J.C., Icarus 42, 257, 1980. - Tomita, K., Saito, T. and Minami, S., Astron. Astrophys. 187, 215, 1987. - Voelzke, M.R., Publications of the Astronomical Society of the Pacific 108, Number 729, 1063, 1996.

  20. Mapping α Centauri AB for Possible Habitable Planets

    Science.gov (United States)

    Quarles, Billy L.; Lissauer, Jack J.

    2016-06-01

    The alpha Centauri AB star system, our closest stellar neighbors, has been studied for many decades and ACESat (Belikov et al. AAS Meeting #225, #311.01, 2015) is a proposed space mission designed to directly image Earth-sized planets in the habitable zones of both of these stars. The alpha Centauri system is older than our Sun, so any resident planets are expected to occupy long-lived orbits. We evaluate the extent of these trajectories where planets are able to orbit for billion-year timescales. The distribution of long-lived orbits is mapped to the sky plane to indicate regions where planets may appear relative to each stellar component. Our results confirm qualitatively those of Wiegert & Holman (Astron. J. 113, 1445, 1997) regarding the approximate size of the regions of stable orbits, which are larger for retrograde orbits relative to the binary than for prograde orbits. Moreover, we find that orbits beyond each star’s habitable zone are affected by a dynamical imprint from the binary orbit due to mean motion resonances and the Lidov-Kozai Mechanism. Stable planets can exist near the plane of the binary orbit within each stellar habitable zone, whereas highly inclined orbits are typically short-lived. These results are of special interest as they can guide the search process of our stellar neighbors in future missions.

  1. 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.

  2. 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...

  3. 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.

    2017-01-01

    We present high-resolution, long-slit spectroscopic observations of two planetary nebulae, M 1-32 and M 3-15, with [WC] central stars located near the Galactic bulge. The observations were obtained with the 2.1-m telescope of 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 planetary nebulae, 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 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 asymptotic giant branch 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 through 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'.

  4. 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.

  5. 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.

  6. Night Sky Brightness at San Pedro Martir Observatory

    Science.gov (United States)

    Plauchu-Frayn, I.; Richer, M. G.; Colorado, E.; Herrera, J.; Córdova, A.; Ceseña, U.; Ávila, F.

    2017-03-01

    We present optical UBVRI zenith night sky brightness measurements collected on 18 nights during 2013 to 2016 and SQM measurements obtained daily over 20 months during 2014 to 2016 at the Observatorio Astronómico Nacional on the Sierra San Pedro Mártir (OAN-SPM) in México. The UBVRI data is based upon CCD images obtained with the 0.84 m and 2.12 m telescopes, while the SQM data is obtained with a high-sensitivity, low-cost photometer. The typical moonless night sky brightness at zenith averaged over the whole period is U = 22.68, B = 23.10, V = 21.84, R = 21.04, I = 19.36, and SQM = 21.88 {mag} {{arcsec}}-2, once corrected for zodiacal light. We find no seasonal variation of the night sky brightness measured with the SQM. The typical night sky brightness values found at OAN-SPM are similar to those reported for other astronomical dark sites at a similar phase of the solar cycle. We find a trend of decreasing night sky brightness with decreasing solar activity during period of the observations. This trend implies that the sky has become darker by Δ U = 0.7, Δ B = 0.5, Δ V = 0.3, Δ R=0.5 mag arcsec‑2 since early 2014 due to the present solar cycle.

  7. 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 ...

  8. Quasi periodic oscillations of solar active regions in connection with their flare activity - NoRH observations

    CERN Document Server

    Abramov-Maximov, Vladimir E; Shibasaki, Kiyoto

    2011-01-01

    The sunspot-associated sources at the frequency of 17 GHz give information on plasma parameters in the regions of magnetic field about B=2000 G at the level of the chromosphere-corona transition region. The observations of short period (from 1 to 10 minutes) oscillations in sunspots reflect propagation of magnetohydrodynamic (MHD) waves in the magnetic flux tubes of the sunspots. We investigate the oscillation parameters in active regions in connection with their flare activity. We confirm the existence of a link between the oscillation spectrum and flare activity. We find differences in the oscillations between pre-flare and post-flare phases. In particular, we demonstrate a case of powerful three-minute oscillations that start just before the burst. This event is similar to the cases of the precursors investigated by Sych, R. et al. (Astron. Astrophys., vol.505, p.791, 2009). We also found well-defined eight-minute oscillations of microwave emission from sunspot. We interpret our observations in terms of a ...

  9. Kinematics of AGN and Quasar Jets

    CERN Document Server

    Kellermann, K I; Homan, D C; Kovalev, Y Y; Kadler, M; Cohen, M C

    2008-01-01

    The major multi-epoch VLBA programs are described and discussed in terms of relativistic beaming models. Broadly speaking the observed kinematics are consistent with models having a parent population which is only mildly relativistic but with Lorentz factors extending up to about 30. While the collimation and acceleration appears to mainly occur close to the central engine, there is evidence of accelerations up to 1 kpc downstream. Generally the motion appears to be linear, but in some sources the motion follows a curved trajectory. In other sources, successive features appear to be ejected in different directions possibly the result of a precessing nozzle. The launch of GLAST in 2008 will offer new opportunities to study the relation between radio and gamma-ray activity, and possibly to locate the source of the gamma-ray emission. VSOP-2 will give enhanced resolution and will facilitate the study of the two-dimensional structure of relativistic jets, while RadioAstron will provide unprecedented resolution to...

  10. Internal Structure and Kinematics of the M87 Inner Radio Jet

    Science.gov (United States)

    Kellermann, Kenneth I.; Kovalev, Y. Y.; Lister, M. L.; Lobanov, A.

    2007-05-01

    M87 was the first galaxy recognized to have a relativistic jet (Sklovsky, 1963, Astron. Zh. 40, 972). Previous radio, optical, and X-ray observations show nearly identical jet structure extending some 20 arcseconds (1.6 kpc) away from the galaxy nucleus. Beyond 5 mas (0.4 pc) from the base, the jet appears to break into two trails which extend out to about 100 mas (8 pc). However, it isn’t clear if the dual appearance is due to the bifurcation of the jet or if it dual is the result of an edge brightened optically thin cone. We have also detected a faint counter-jet. Repeated observations made since 1994 trace the motion of a number of jet features. Some parts of the inner jet appear stationary while other parts move with apparent speeds only up to about 0.6 times the speed of light. This is in contrast to the much large speeds which have been reported at radio and at optical wavelengths further along the jet.

  11. Revisiting ISEE-3-Voyager Observations of Back-Side Type III Radio Bursts in View of the Stereo/Waves observations.

    Science.gov (United States)

    Bougeret, J.; Lecacheux, A.; Hoang, S.; Maksimovic, M.

    2004-12-01

    In this paper, we revisit old observations of interplanetary type III radio bursts made simultaneously by the radio instruments on the ISEE-3 spacecraft and on the Voyager spacecraft, in view of the new opportunities offered by the Stereo mission.. Type III radio emission is produced by beams of supra-thermal electrons believed to be accelerated during the flare process and traveling along open interplanetary field lines. Their observation can help trace the large scale structure of the interplanetary medium. Lecacheux et al. (1989) analyzed the properties of such radio bursts originating behind the Sun as viewed from the Earth and still also observed by the ISEE-3 spacecraft located at the L1 libration point. Information on the beaming of the radiation can be deduced from these observations. Lecacheux et al. also measured anomalous delays in burst arrival time at one spacecraft relative to the other. These anomalous delays could be explained by the presence of both the fundamental and harmonic radiation modes with different beaming properties. Such an hypothesis can be checked by the Stereo/Waves observations. Finally, we discuss previous radio wave propagation models in the interplanetary medium and emphasize their importance for the interpretation of the radio observations. Lecacheux, A., J.-L. Steinberg, S. Hoang, and G. A. Dulk, Characteristics of type III bursts in the solar wind from simultaneous observations on board ISEE-3 and Voyager, Astron. Astrophys. 217, 237-250, 1989.

  12. 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...

  13. 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.

  14. 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.

  15. Stellar multiplicity of the open cluster ASCC 113

    Energy Technology Data Exchange (ETDEWEB)

    Guerrero, C. A.; Orlov, V. G.; Monroy-Rodríguez, M. A.; Voitsekhovich, V. V., E-mail: cguerrero@astro.unam.mx, E-mail: orlov@astro.unam.mx, E-mail: mmonroy@astro.unam.mx, E-mail: voisteko@astro.unam.mx [Instituto de Astronomía, Universidad Nacional Autónoma de México, México, D. F. 04510 (Mexico)

    2014-02-01

    We present a high angular resolution survey for binary and multiple stars in the Galactic open cluster ASCC 113. Our observations were conducted on the 2.1 m telescope of the Observatorio Astronómico Nacional, Sierra San Pedro Mártir, México. Combining our results with data taken from the literature, we found a ratio of the number of single to binary stars to be 27:7 for the most probable members, so the multiplicity fraction for this cluster is 20.6% ± 3%. We also observed field stars in the vicinity of the cluster and estimated a ratio of multiplicities to be 125:27:4:1:0:0:0:1 (between one and eight companions), equivalent to a multiplicity fraction of 20.9% ± 1%. We estimated the number of undetected companions in our sample to be very small. Comparing the multiplicity frequency of the cluster with the frequency of the field, we concluded that they are statistically indistinguishable from each other. We provide a brief review on the topic of stellar multiplicity in open clusters.

  16. 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.

  17. 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.

  18. 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.

  19. 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...

  20. 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.

  1. 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

  2. Bown dwarf and very low mass stars search in orion ob1a and ob1b asociations

    Directory of Open Access Journals (Sweden)

    J. J. Downes

    2006-01-01

    Full Text Available Se presentan los resultados iniciales de la primera b usqueda optica e infrarroja a gran escala de enanas marrones en la regi on de formaci on estelar de Ori on. Las observaciones opticas fueron hechas con el telescopio Schmidt Jurgen Stock y la c amara QUEST-1 del Observatorio Astron omico Nacional de Venezuela y cubren un area de 180 grad2 de los cuales 32grad2, que incluyen una porci on de la subregi on OB1a y la casi totalidad de OB1b, se estudian en este trabajo. Las observaciones en las bandas R e I fueron procesadas mediante una t ecnica de suma de im agenes incrementando las magnitudes l mite a I = 20.5 y R = 21.5 con completitud hasta I = 19.0 y R = 20.0. La fotometr a infrarroja en las bandas J, H and K se obtuvo de la base de datos del sondeo Two Micron All Sky Survey. Observaciones espectrosc opicas de una primera muestra de candidatas, realizadas con HECTOSPEC, permitieron la con rmaci on de 15 estrellas de muy baja masa y 9 enanas marrones.

  3. DDOTI: the deca-degree optical transient imager

    Science.gov (United States)

    Watson, Alan M.; Lee, William H.; 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; Gómez Maqueo Chew, Yilen; Klotz, Alain; Quirós, Fernando; Reyes-Ruíz, Maurico; Ruíz-Díaz-Soto, Jaime; Thierry, Pierre; Tinoco, Silvio

    2016-07-01

    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 deg2, will have 2 arcsec pixels, and will reach a 10σ 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 deg2. DDOTI uses commercial components almost entirely. The first DDOTI will be installed at the Observatorio Astronómico Nacional in Sierra San Pedro Martír, Baja California, México 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 installation costs only about US$500,000. This makes it possible to contemplate a global network of DDOTI installations. Such geographic diversity would give earlier access and a higher localization rate. We are actively exploring this option.

  4. UBV stellar photometry of bright stars in GC M5. I. UV colour-magnitude and colour-colour diagrams and some peculiarities in the HB stellar distribution

    CERN Document Server

    Markov, H; Baev, P V; Markov, Haralambi; Spassova, Nedka; Baev, Plamen

    2001-01-01

    We present stellar photometry in the UBV passbands for the globular cluster M5 = NGC5904. The observations, short-exposured photographic plates and CCD frames, were obtained in the RC-focus of the 2m telescope of the Natl. Astron. Obs. 'Rozhen'. All stars in an annulus with radius 1 < r < 5.5 arcmin were measured. We show that the UV CMDs describe different evolutionary stages in a better manner than the 'classical' (V, B-V) diagram. We use HB stars, with known spectroscopic Teff, to check the validity of the colour zero-point. A review of all known UV-bright star candidates in M5 is made and some of their parameters are catalogued. Six new stars of this kind are suspected on the basis of their position on the CMD. New assessment of the cluster reddening and metallicity is done using the (U-B, B-V) diagram. We find [Fe/H]= -1.38, which confirms the Zinn & West (1984) value contrasting with recent spectroscopic estimates. In an effort to clarify the question of the gap in the BHB stellar distribution...

  5. 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...

  6. 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.

  7. STAR IMAGE SHAPE TRANSFORMER FOR ASTRONOMICAL SLIT SPECTROSCOPY

    Directory of Open Access Journals (Sweden)

    O. Cardona

    2010-01-01

    Full Text Available Presentamos un nuevo transformador de la forma de las imágenes estelares para espectroscopía astronómica de rendija que consiste de una lente plano convexa pegada a una placa rectangular plana paralela de vidrio en uno de sus lados menores con el fin de mejorar el desempeNo de los sistemas espectrométricos. El sistema cambia la forma de los objetos a la forma rectangular con el propósito de llenar con luz la abertura de entrada de la rendija en los sistemas espectroscópicos. La placa se pone de lado con la lente como la abertura de entrada y la abertura de salida es la rendija iluminada vista por el sistema espectrométrico. El objetivo de este transformador es también el de mantener las características del haz de luz, la resolución intrínseca del espectrómetro y de mejorar la eficiencia de los sistemas espectrométricos y detectores.

  8. 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.

  9. 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...

  10. La regeneración de la astronomía y la meteorología españolas: Augusto Arcimís (1844-1910 y el institucionismo

    Directory of Open Access Journals (Sweden)

    Anduaga Egaña, Aitor

    2005-12-01

    Full Text Available The article is about the attempts for regenerating Spanish astronomy and meteorology in the last quarter of the twentieth century through the human and scientific trajectory of Augusto Arcimís (1844-1910, amateur astronomer and the first Spanish professional meteorologist. The role of personalities linked to the Institución Libre de Enseñanza in the creation of the Instituto Central Meteorológico in 1887 and the spread of modern astronomical theories is analyzed.

    El artículo trata sobre los intentos por regenerar la astronomía y la meteorología españolas durante el último cuarto del siglo XIX a través de la trayectoria científica y humana del astrónomo amateur y primer meteorólogo profesional español Augusto Arcimís (1844-1910. Se estudia el papel de personalidades vinculadas a la Institución Libre de Enseñanza en la creación del Instituto Central Meteorológico en 1887 y en la difusión de teorías astronómicas modernas.

  11. 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.

  12. 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...

  13. 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.

  14. NASA's High Energy Vision: Chandra and the X-Ray Universe

    Science.gov (United States)

    Mais, D. E.; Stencel, R. E.; Richards, D.

    2004-05-01

    The Chandra X-Ray Observatory is the most sophisticated X-ray observatory launched by NASA. Chandra is designed to observe X-rays from high-energy regions of the universe, such as the remnants of supernovae explosions, col- liding galaxies, black holes, pulsars, neutron stars, quasars, and X-ray bi- nary stars. The spectacular results from the first five years of Chandra ob- servations are changing and redefining theories with each observation. Every exciting new image shows glimpses of such exotic phenomena as super-massive black holes, surprising black hole activity in old galaxies, rivers of grav- ity that define the cosmic landscape, unexpected x-ray activity in proto- stars and failed stars, puzzling distributions of elements in supernovae remnants, the sound waves from a super-massive black hole, and the even the tantalizing possibility of an entirely new form of matter - the strange quark star. On September 14, 2000, triggered by alerts from amateur astron- omers worldwide, Chandra observed the outburst of the brightest northern dwarf nova SS Cygni. The cooperation of hundreds of amateur variable star astronomers and the Chandra X-Ray scientists and spacecraft specialists pro- vided proof that the collaboration of amateur and professional astronomers is a powerful tool to study cosmic phenomena.

  15. The IMPACTON Project: Pole and Shape of Seven near-Earth Asteroids

    Science.gov (United States)

    Lazzaro, Daniela; Silva, José Sergio; Rodrigues, Teresinha; Márcio Carvano, Jorge; Roig, Fernando; Souza, Roberto Pereira e.; IMPACTON Team

    2015-08-01

    The formation and evolution of Solar System small bodies, in particular those in near-Earth orbits, is a complex problem which solution strongly depends on a better knowledge of their physical properties. To contribute to the international efforts in this direction the IMPACTON project (www.on.br/IMPACTON) set up a dedicated facility in a remote region in the northeast part of Brazil, denominated Observatório Astronômico do Sertão de Itaparica (OASI - code Y28, Itacuruba).Using the 1-m telescope of the OASI we observed more of 40 NEAs during several observational runs between March 2012 and October 2014. Our observations were made using an Apogee Alta U47 CCD camera, 1024 X 1024 pixels, giving a 5.9 x 5.9 arcmin field, and using an R Johnson filter.Standard reduction procedures were applied and relative magnitudes were used to obtain lightcurves for the observed asteroids. The application of the inversion of method developed by Kaasalainen and Torppa (2001) and Kaasalainen et al. (2001) allowed us to derive the rotational period for 14 NEAs and, for 7 of these, also the pole direction and the shape. The implications of the obtained results will be discussed.

  16. The IMPACTON Project: Pole and Shape of Eight Near-Earth Asteroids†

    Science.gov (United States)

    Silva, José Sergio; Lazzaro, Daniela; Rodrigues, Teresinha; Carvano, Jorge Márcio; Roig, Fernando; Souza, Roberto; Aff001

    2016-01-01

    The formation and evolution of Solar System small bodies, in particular those in near-Earth orbits, is a complex problem which solution strongly depends on a better knowledge of their physical properties. To contribute to the international efforts in this direction the IMPACTON project (www.on.br/IMPACTON) set up a dedicated facility denominated Observatório Astronômico do Sertão de Itaparica (OASI). Using the 1-m telescope several dozens of NEAs were observed between March 2012 and October 2014. Here we will present the results obtained for 8 objects. Relative magnitudes were used to obtain lightcurves and derive rotational periods. Applying the inversion method developed by Kaasalainen and Torppa (2001) and Kaasalainen et al. (2001), along with lightcurves from literature, allowed to refine the rotational period of these asteroids as well as to derive their pole direction and shape. The obtained results confirm a lack of poles toward the ecliptic and with a majority of retrograde rotators. A more representative sample, however, is needed in order to drive robust conclusions.

  17. Observations of the stratorotational instability in rotating concentric cylinders

    Science.gov (United States)

    Ibanez, Ruy; Swinney, Harry L.; Rodenborn, Bruce

    2016-09-01

    We study the stability of density stratified flow between corotating vertical cylinders with rotation rates ΩoTaylor vortex flow but to a nonaxisymmetric stratorotational instability (SRI). The present work extends the range of Reynolds numbers and buoyancy frequencies [N =√{(-g /ρ )(∂ ρ /∂ z ) }] examined in previous experiments. We present the first experimental results for the axial wavelength λ of the instability as a function of the internal Froude number, Fr=Ωi/N ; λ increases by nearly an order of magnitude over the range of Fr examined. For small outer cylinder Reynolds number, the SRI occurs for inner inner Reynolds number larger than for the axisymmetric Taylor vortex flow (i.e., the SRI is more stable). For somewhat larger outer Reynolds numbers the SRI occurs for smaller inner Reynolds numbers than Taylor vortex flow and even below the Rayleigh stability line for an inviscid fluid. Shalybkov and Rüdiger [Astron. Astrophys. 438, 411 (2005), 10.1051/0004-6361:20042492] proposed that the laminar state of a stably stratified rotating shear flow should be stable for Ωo/Ωi>ri/ro , but we find that this stability criterion is violated for N sufficiently large. At large Reynolds number the primary instability is not the SRI but a previously unreported nonperiodic state that mixes the fluid.

  18. Alcune osservazioni sulle occorenze di Crux in Manilio, Séneca, Giovenale, Marziale

    Directory of Open Access Journals (Sweden)

    Ilaria Ramelli

    1999-01-01

    Full Text Available II supplizio della croce appare un tema particolarmente presente e diffuso nella letteratura latina del i secólo d.C. Manilio, nel V libro del suoi Astronómica, per la prima voita attñbuisce la croce ad Andrómeda, operando una vistosa innovazione all'interno della tradizione mitografica. Ma anche Petronio, tucano. Séneca, Giovenale e Marziale parlano piú volte della croce. Séneca ne appare Impresslonato in modo speclale e Marziale cita il caso di uno schiavo crocifisso per avere Incendiato Roma. Cosi Giovenale sembra fare allusione ai supplizl inflitti ai Cristiani con l'accusa di avere incendiato Roma (64 d.C..The torment of the cross is a theme that Is partlcularly present in the Román literatura of the ist century A.D. Manilius for the first time ascrlbes the cross to Andrómeda, with a remarkable innovation in the mythographic tradition. But also Petronius, Lucan, Séneca, Juvenai and Martial In several occasions mention the cross. Séneca appears particuiariy impressed by this torment. Martial represents a slave hanging from the cross as guilty of the fire of Rome. And so Juvenai seems to allude to the torments infiicted to the Christians as scapegoats of the fire of Rome (64 A.D..

  19. Europa: Characterization and interpretation of global spectral surface units

    Science.gov (United States)

    Nelson, M.L.; McCord, T.B.; Clark, R.N.; Johnson, T.V.; Matson, D.L.; Mosher, J.A.; Soderblom, L.A.

    1986-01-01

    The Voyager global multispectral mosaic of the Galilean satellite Europa (T. V. Johnson, L. A. Soderblom, J. A. Mosher, G. E. Danielson, A. F. Cook, and P. Kupferman, 1983, J. Geophys. Res. 88, 5789-5805) was analyzed to map surface units with similar optical properties (T. B. McCord, M. L. Nelson, R. N. Clark, A. Meloy, W. Harrison, T. V. Johnson, D. L. Matson, J. A. Mosher, and L. Soderblom, 1982, Bull Amer. Astron. Soc. 14, 737). Color assignments in the unit map are indicative of the spectral nature of the unit. The unit maps make it possible to infer extensions of the geologic units mapped by B. K. Lucchitta and L. A. Soderblom (1982, in Satellites of Jupiter, pp. 521-555, Univ. of Arizona Press, Tucson) beyond the region covered in the high-resolution imagery. The most striking feature in the unit maps is a strong hemispheric asymmetry. It is seen most clearly in the ultraviolet/violet albedo ratio image, because the asymmetry becomes more intense as the wavelength decreases. It appears as if the surface has been darkened, most intensely in the center of the trailing hemisphere and decreasing gradually, essentially as the cosine of the angle from the antapex of motion, to a minimum in the center of the leading hemisphere. The cosine pattern suggests that the darkening is exogenic in origin and is interpreted as evidence of alteration of the surface by ion bombardment from the Jovian magnetosphere. ?? 1986.

  20. Mapping the Region in the Nearest Star System to Search for Habitable Planets

    Science.gov (United States)

    Lissauer, Jack J.; Quarles, B.

    2015-01-01

    Circumstellar planets within the alpha Centauri AB star system have been suggested through formation models and recent observations, and ACESat (Belikov et al. AAS Meeting #225, #311.01, 2015) is a proposed space mission designed to directly image Earth-sized planets in the habitable zones of both of these stars. 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, 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. Overall, orbits in the habitable zones near the plane of the binary are stable, whereas high-inclination orbits are short-lived.

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

    Science.gov (United States)

    Lissauer, Jack; Quarles, Billy

    2015-01-01

    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 pro-grade 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. Overall, orbits of a single planet in the habitable zones near the plane of the binary are stable, whereas high-inclination orbits are short-lived. However, even well within regions where single planets are stable, multiple planet systems must be significantly more widely-spaced than they need to be around an isolated star in order to be long-lived.

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

    Science.gov (United States)

    Lemaire, J. F.; Stegen, K.

    2016-12-01

    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 < 1.3 R_{⊙}) the DYN method gives the same results as the HST method. The effects of the other free parameters on the DYN temperature distribution are presented in the last part of this study. Our DYN method is a new tool to evaluate the range of altitudes where the heating rate is maximum in the solar corona when the electron-density distribution is obtained from WL coronal observations.

  3. 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.

  4. 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.

  5. H$_2$O Masers and Protoplanetary Disk Dynamics in IC 1396 N

    CERN Document Server

    Bayandina, O S; Kurtz, S E; Rudnitskij, G M; Alakoz, A V

    2016-01-01

    We report H$_2$O maser line observations of the bright-rimmed globule IC 1396 N using a ground-space interferometer with the 10-m RadioAstron radio telescope as the space-based element. The source was not detected on projected baselines >2.3 Earth diameters, which indicates a lower limit on the maser size of L >0.03 AU and an upper limit on the brightness temperature of 6.25 x 10$^{12}$ K. Positions and flux densities of maser spots were determined by fringe rate mapping. Multiple low-velocity features from -4.5 km/s to +0.7 km/s are seen, and two high-velocity features of V$_{LSR}$=-9.4 km/s and +4.4 km/s are found at projected distances of 157 AU and 70 AU, respectively, from the strongest low-velocity feature at V$_{LSR}$=$\\sim$0.3 km/s. Maser components from the central part of the spectrum fall into four velocity groups but into three spatial groups. Three spatial groups of low-velocity features detected in the 2014 observations are arranged in a linear structure about 200 AU in length. Two of these grou...

  6. 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: $\\theta_{scat}$...

  7. El círculo meridiano automático de San Fernando - San Juan. Sus primeros pasos en el hemisferio sur

    Science.gov (United States)

    Mallamaci, C. C.; Muiños, J. L.; Gallego, M.; Pérez, J. A.; Marmolejo, L.; Navarro, J. L.; Sedeño, J.; Vallejos, M.; Belizón, F.

    Se informa sobre el estado actual del Círculo Meridiano Automático de San Fernando-San Juan. El instrumento (Grubb-Parson, de 178mm de abertura y 2665 mm de distancia focal) es gemelo del que se encuentra en las Islas Canarias, y fue instalado durante los meses de julio y agosto de 1996 en la estación astronómica ``Dr. C.U.Cesco" (El Leoncito, Barreal), a unos 200 km de distancia de la ciudad de San Juan, merced a un Convenio de Cooperación Científica, firmado en 1994 entre el ROA (España) y el OAFA (Argentina). En la actualidad se está llevando a cabo un programa de prueba cuyos resultados preliminares muestran que el telescopio está en buenas condiciones para observar estrellas de hasta magnitud aproximada 14.5, con buenos errores de observación (<0.12" en ascensión recta y declinación).

  8. A new class of solutions of compact stars with charged distributions on pseudo-spheroidal spacetime

    CERN Document Server

    Thomas, V O

    2015-01-01

    In this paper a new class of exact solutions of Einstein's field equations for compact stars with charged distributions is obtained on the basis of pseudo-spheroidal spacetime characterized by the metric potential $g_{rr}=\\frac{1+K\\frac{r^{2}}{R^{2}}}{1+\\frac{r^{2}}{R^{2}}}$, where $K$ and $R$ are geometric parameters of the spacetime. The expressions for radial pressure ($ p_r $) and electric field intensity ($ E $) are chosen in such a way that the model falls in the category of physically acceptable one. The bounds of geometric parameter $K$ and the physical parameters $ p_0 $ and $\\alpha$ are obtained by imposing the physical requirements and regularity conditions. The present model is in good agreement with the observational data of various compact stars like 4U 1820-30, PSR J1903+327, 4U 1608-52, Vela X-1, SMC X-4, Cen X-3 given by Gangopadhyay {\\em{et al.}} [Gangopadhyay T., Ray S., Li X-D., Dey J. and Dey M., {\\it Mon. Not. R. Astron. Soc.} {\\bf431} (2013) 3216]. When $ \\alpha = 0, $ the model reduces...

  9. 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...

  10. 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 ...

  11. 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...

  12. 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.

  13. Simulation of the Earth's paleo-magnetosphere for the late Hadean eon

    Science.gov (United States)

    Scherf, Manuel; Khodachenko, Maxim; Blokhina, Marina; Johnstone, Colin; Alexeev, Igor; Belenkaya, Elena; Tarduno, John; Güdel, Manuel; Lammer, Helmut

    2016-04-01

    pc as oval co-latitude) and magnetospheric subsolar distance Rs is sin2Θpc = Re/Rs. Acknowledgments. The authors acknowledge the support of the FWF NFN project S116-N16 "Pathways to Habitability", in particular the related subproject S11606-N16 "Magnetospheric electrodynamics of exoplanets". This publication is supported by the Austrian Science Fund (FWF). References: Alexeev, I. I., Belenkaya, E. S., Bobrovnikov, S. Y., and Kalegaev, V. V. (2003), Modelling of the electromagnetic field in the interplanetary space and in the Earth's magnetosphere, Space Sci. Rev., 107, 7-26. Johnstone, C.P., Güdel, M., Lüftinger, T., Toth, G., and Brott, I. (2015), Stellar winds on the main-sequence: I. Wind model, Astron. Astrophys., 577, id.A28. Johnstone, C.P., Güdel, M., Brott, I., and Lüftinger, T. (2015), Stellar winds on the main-sequence: II. The evolution of rotation and winds, Astron. Astrophys., 577, id.A27. Tarduno, J. A., Cottrell, R. D., Davis, W. J., Nimmo, F., and Bono, R. K. (2015), A Hadean to Paleoarchean geodynamo recorded by single zircon crystals, Science, 349, 521-524.

  14. An investigation of the low-ΔV near-Earth asteroids (341843) 2008 EV5 and (52381) 1993 HA. Two suitable targets for the ARM and MarcoPolo-M5 space missions

    Science.gov (United States)

    Perna, D.; Popescu, M.; Monteiro, F.; Lantz, C.; Lazzaro, D.; Merlin, F.

    2017-01-01

    Context. The Asteroid Redirect Mission (ARM) under development by NASA is being planned to collect a multi-meter boulder from a near-Earth asteroid (NEA), and to bring it to the cis-lunar space in the mid-2020's for future study and exploitation by a crewed mission. The MarcoPolo-M5 project is being proposed in 2016 for the M5 mission opportunity by ESA, to bring back to Earth a sample from a very primitive D-type NEA. As D-types are very rare within the NEA population, considerable effort is still in progress to characterize easily accessible targets with unknown surface composition, in order to discover further asteroids that belong to this taxonomic group. Aims: We aim to further characterize the physical properties of two optimal targets for sample return space missions, the low-ΔV NEAs (341843) 2008 EV5 and (52381) 1993 HA. The asteroid 2008 EV5 is the baseline target of ARM, but only one spectrum of this object exists in the literature. The asteroid 1993 HA is a very favourable target for a space mission based on its dynamical properties: here we intend to assess if it is a suitable target for MarcoPolo-M5. Methods: We obtained visible spectroscopy of 2008 EV5 with the FORS2 instrument at ESO-VLT (Paranal, Chile), at different rotational phases. We also obtained visible and near-infrared spectroscopy of 1993 HA, using the EFOSC2 and SOfI instruments at ESO-NTT (La Silla, Chile). Visible photometry of 1993 HA was carried out within the IMPACTON project at the Observatório Astronômico do Sertão de Itaparica (Itacuruba, Brazil). Results: Our new observations are in agreement with the C-type classification of 2008 EV5, which is a requirement for the ARM mission. We obtained five visible spectra which do not show any variability within the limits of noise, suggesting a homogeneous surface. We obtained the first ever spectroscopic dataset ( 0.4-1.6 μm) for 1993 HA, finding a featureless, red-sloped behaviour typical of D-types (a T or X classification is also

  15. Eventos de Desconexão no Cometa P/Halley sob a Ótica do Modelo de Reconexão Magnética

    Science.gov (United States)

    Voelzke, M. R.; Matsuura, O. T.

    1998-08-01

    determinam o tempo de desconexão a partir de um movimento linear constantemente acelerado (Yi et al., 1994). A velocidade de um DE para outro varia enormemente. - Brandt, J.C., Niedner, M.B.Jr. and Rahe, J., (1992) The International Halley Watch Atlas of Large-Scale Phenomena (printed by: Johnson Printing Co., Boulder, CO), University of Colorado-Boulder. - Celnik, W.E., Koczet, P., Schlosser, W., Schulz, R., Svejda, P. and Weissbauer, K., (1988) Astron. Astrophys. Suppl. Ser. 72, 89. - Delva, M., Schwingenschuh, K., Niedner, M.B.Jr. and Gringauz, K.I., (1991) Planet. Space Sci. 39, Number 5, 697. - Hoeksema, J.T., (1989) Adv. Space Res. 9, 141. - Jockers, K., (1985) Astron. Astrophys. Suppl. Ser. 62, 791. - Niedner, M.B.Jr. and Brandt, J.C., (1979) Astrophys. J. 234, 723. - Voelzke, M.R. and Matsuura, O.T., (1988) Planet. Space Sci. 46, 835. - Yi, Y., Caputo, M.F. and Brandt, J.C., (1994) Planet. Space Sci. 42, Number 9, 705.

  16. 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

  17. Analysis on establishing Chang'E-3 landing site as a reflectance calibration target

    Science.gov (United States)

    Liu, Bin; Fu, Xiaohui; Zeng, Xingguo; Yao, Meijuan; Zhang, Hongbo; Su, Yan; Zhao, Shu; Xue, Xiping; Li, Chunlai; Zou, Yongliao

    2015-04-01

    landing site is homogeneous according to the two detection results of APXS on elements in lunar soil. At last, we compare and scale the four detection points' reflectance of VNIS, which demonstrate that the reflectance of the landing site are quite similar at the spectral range 450nm-1750nm, but differences still existed beyond 1750nm. Future work is still needed, such as photometric calibration of VNIS data, and errors estimation on reflectance calculation. Besides, the location and spatial coverage of the reflectance calibration target should be determined and its calibration accuracy should be evaluated. Acknowledgements: This work was supported by the National Natural Science Foundation of China (No.11403049 and 41490633). References: [1] J. K. Hillier et al., (1999) Icarus, 141, 205-225. [2] M. Ohtake et al., (2010) Space Sci. Rev., 154, 57-77. [3] M. Ohtake et al., (2010) Icarus, 226, 364-374. [4] B. Liu et al., (2014) RAA, 14, 1674. [5] L. Qiao et al., (2013) Sci Sin-Phys Mech Astron, 43, 1370-1386. [6] J. N. Zhao et al., (2014) Sci China-Phys Mech Astron, 57, 569-576. [7] C. L. Li et al., (2014) RAA, 14, 1514. [8] X. H. Fu et al., (2014) RAA, 14, 1595.

  18. Near Earth asteroids associated with the Sigma-Capricornids meteoroid stream

    Science.gov (United States)

    Gulchekhra, Kokhirova; Pulat, Babadzhanov; Umed, Khamroev

    drift of the sigma-Capricornids were determined. Further to the PE criterion (Ceplecha, McCrosky 1976), the values of bulk density of the nine fireball producing meteoroids are in the range 0.2-3.5 g cm(-3) that suggests a non-homogeneous compound of the comet-progenitor of the sigma-Capricornids fireball shower. size{ References Babadzhanov, P.B., 2003, A&A,397, 319 Babadzhanov, P.B., Kokhirova, G.I., 2009, Izv. Ak. Nauk Resp. Taj.,2(135),46 Babadzhanov, P.B., Obrubov, Yu.V., 1992, Cel. Mech.& Dyn. Astron., v.54, p.111 Ceplecha, Z., McCrosky, R.E.J., 1976, J. Geophys. Res., 81, 6257 Halliday, I., Griffin, A.A., Blackwell, A.T., 1996, Met.& Planet. Sci., 31, 185 Jenniskens, P., 2006, Meteor showers and their parent comets, New- York: Cambridge Univ. Press, p. 790 Kosai, H., 1992, Cel. Mech. & Dyn. Astron., 54, 237 Kresak, L., 1982, BAC, 33, 104 McCrosky, R.E., Shao, C.Y., Posen, A., 1978, Meteoritika, 37, 44 Sekanina Z., 1973, Icarus, 18, 253 Sekanina Z., 1976, Icarus, 27, 265 Southworth, R.B., Hawkins, G.S., 1963, Smith. Cont. Aph. 7, 261}

  19. Dynamical passage to approximate equilibrium shapes for spinning, gravitating rubble asteroids

    Science.gov (United States)

    Sharma, Ishan; Jenkins, James T.; Burns, Joseph A.

    2009-03-01

    Many asteroids are thought to be particle aggregates held together principally by self-gravity. Here we study — for static and dynamical situations — the equilibrium shapes of spinning asteroids that are permitted for rubble piles. As in the case of spinning fluid masses, not all shapes are compatible with a granular rheology. We take the asteroid to always be an ellipsoid with an interior modeled as a rigid-plastic, cohesion-less material with a Drucker-Prager yield criterion. Using an approximate volume-averaged procedure, based on the classical method of moments, we investigate the dynamical process by which such objects may achieve equilibrium. We first collapse our dynamical approach to its statical limit to derive regions in spin-shape parameter space that allow equilibrium solutions to exist. At present, only a graphical illustration of these solutions for a prolate ellipsoid following the Drucker-Prager failure law is available [Sharma, I., Jenkins, J.T., Burns, J.A., 2005a. Bull. Am. Astron. Soc. 37, 643; Sharma, I., Jenkins, J.T., Burns, J.A., 2005b. Equilibrium shapes of ellipsoidal soil asteroids. In: García-Rojo, R., Hermann, H.J., McNamara, S. (Eds.), Proceedings of the 5th International Conference on Micromechanics of Granular Media, vol. 1. A.A. Balkema, UK; Holsapple, K.A., 2007. Icarus 187, 500-509]. Here, we obtain the equilibrium landscapes for general triaxial ellipsoids, as well as provide the requisite governing formulae. In addition, we demonstrate that it may be possible to better interpret the results of Richardson et al. [Richardson, D.C., Elankumaran, P., Sanderson, R.E., 2005. Icarus 173, 349-361] within the context of a Drucker-Prager material. The graphical result for prolate ellipsoids in the static limit is the same as those of Holsapple [Holsapple, K.A., 2007. Icarus 187, 500-509] because, when worked out, his final equations will match ours. This is because, though the formalisms to reach these expressions differ, in statics

  20. The evolution of a Pluto-like system during the migration of the ice giants

    Science.gov (United States)

    Pires, Pryscilla; Giuliatti Winter, Silvia M.; Gomes, Rodney S.

    2015-01-01

    0.10 AU, none of the systems have been destroyed. The latter sample concentrates 94% of closest approaches with the ice giants. Recall that throughout the early history of the Solar System giant impacts were common (McKinnon, W.B. [1989]. Astrophys. J. 344, L41-L44; Stern, A. [1991]. Icarus 90; Canup, R.M. [2005]. Science 307, 546-550). Also, impacts capable of forming a binary like Pluto-Charon can occur possibly prior to 0.5-1 Gyr (Kenyon, S.J., Bromley, B.C. [2014]. Astron. J. 147, 8), and small satellites such as Nix and Hydra can grow in debris from the giant impact (e.g., Canup, R.M. [2011]. Astron. J. 141, 35). Thus, we conclude that if Pluto and its satellites were emplaced into the KB from lower heliocentric orbits, then the Pluto system could survive the encounters that may have happened for emplacement of the Plutinos through the mechanism proposed by Levison et al.

  1. 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.

  2. 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.

  3. 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.

  4. On the calibration of the COBE/IRAS dust emission reddening maps

    Science.gov (United States)

    Dutra, C. M.; Ahumada, A. V.; Clariá, J. J.; Bica, E.; Barbuy, B.

    2003-09-01

    In this work we study the spectral properties (3600-6800 Å) of the nuclear region of early-type galaxies at low (|b|B-V) reddening values of the galaxies by matching their continuum distribution with respect to those of reddening-free spectral galaxy templates with similar stellar populations. We also compare the spectroscopic reddening value of each galaxy with that derived from 100 mu m dust emission (E(B-V)FIR) in its line of sight, and we find that there is agreement up to E(B-V)=0.25. Beyond this limit E(B-V)FIR values are higher. Taking into account the data up to E(B-V) ~ 0.7, we derive a calibration factor of 0.016 between the spectroscopic E(B-V) values and Schlegel et al.'s (\\cite{Schlegel1998}) opacities. By combining this result with an AK extinction map built within ten degrees of the Galactic centre using Bulge giants as probes (Dutra et al. \\cite{Dutra2003}), we extended the calibration of dust emission reddening maps to low Galactic latitudes down to |b|=4deg and E(B-V)= 1.6 (AV ~ 5). According to this new calibration, a multiplicative factor of ~0.75 must be applied to the COBE/IRAS dust emission reddening maps. Based on observations made at Complejo Astronómico El Leoncito, which is operated under agreement between the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina and the National Universities of La Pata, Córdoba and San Juan, Argentina.

  5. Radial Velocities and Kinematic Membership in the Open Cluster NGC 3114

    Science.gov (United States)

    González, Jorge Federico; Lapasset, Emilio

    2001-05-01

    Echelle spectroscopic observations for 30 bright stars in the field of the sparse open cluster NGC 3114 are presented. The sample includes main-sequence stars, yellow and red giants, and blue straggler candidates. Radial velocities are derived by cross-correlations using high signal-to-noise ratio standard spectra as templates. The cluster mean velocity is well defined from eight giants and several main-sequence stars whose average is =-3.52+/-0.25 km s-1. The membership probabilities of the observed stars are computed on the basis of the velocity distributions of the cluster and field stars, and the expected percentage of contamination at each position. We classified 19 cluster members and 10 nonmembers; the remaining star is a known spectroscopic binary for which no membership probability was assigned. Among the members, there is a bright yellow giant, seven red giants, and four blue straggler candidates, although they should be considered as turn-off stars. The location of two of them in the color-magnitude diagram (slightly blueward of the turn-off) can be explained by their low rotational velocities. No velocity variations were detected in the 16 stars measured more than once, which indicates that NGC 3114 possess an abnormally low binary frequency. From spectral types of cluster members, a distance modulus (V-Mv)=9.8+/-0.2 mag and a reddening E(B-V)=0.07+/-0.01 mag are derived. The cluster age is estimated to be 1.6×108 yr. The observations presented here were obtained at the Complejo Astronómico El Leoncito (CASLEO), which is operated under agreement between the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina (CONICET) and the National Universities of La Plata, Córdoba and San Juan.

  6. Integrated spectral properties of 22 small angular diameter galactic open clusters

    Science.gov (United States)

    Ahumada, A. V.; Clariá, J. J.; Bica, E.

    2007-10-01

    Aims:Flux-calibrated integrated spectra of a sample of 22 Galactic open clusters of small angular diameter are presented. With one exception (ESO 429-SC2), all objects have Galactic longitudes in the range 208° B-V) values for the whole sample vary from 0.0 in ESO 445-SC74 to 1.90 in Pismis 24, while the ages range from ~3 Myr (NGC 6604 and BH 151) to ~3.5 Gyr (Ruprecht 2). For six clusters (Dolidze 34, ESO 429-SC2, ESO 445-SC74, Ruprecht 2, BH 151 and Hogg 9) the foreground E(B-V) colour excesses and ages are determined for the first time. The results obtained for the remaining clusters show, in general terms, good agreement with previous photometric results. Conclusions: The age and reddening distributions of the present sample match those of known clusters in the two selected Galactic sectors. The present results would favour a major dissolution rate of star clusters in these two sectors. Two new solar-metallicity templates are defined corresponding to the age groups of (4-5) Myr and 30 Myr among those of Piatti et al. (2002, MNRAS, 335, 233). The Piatti et al. templates of 20 Myr and (3-4) Gyr are here redefined. Based on observations made at Complejo Astronómico El Leoncito, which is operated under agreement between the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina (CONICET) and the National Universities of La Plata, Córdoba and San Juan, Argentina. Tables [see full text]- [see full text] and Appendix are only available in electronic form at http://www.aanda.org

  7. Optical polarization observations in the Scorpius region: NGC 6124

    Science.gov (United States)

    Vergne, M. Marcela; Feinstein, Carlos; Martínez, Ruben; Orsatti, Ana María; Alvarez, María Paula

    2010-04-01

    We have obtained optical multicolour (UBVRI) linear polarimetric data for 46 of the brightest stars in the area of the open cluster NGC 6124 in order to investigate the properties of the interstellar medium (ISM) that lies along the line of sight towards the cluster. Our data yield a mean polarization efficiency of PV/E(B - V) = 3.1 +/- 0.62, i.e. a value lower than the polarization produced by the ISM with normal efficiency for an average colour excess of E(B - V) = 0.80 as that found for NGC 6124. Besides, the polarization shows an orientation of which is not parallel to the Galactic disc, an effect that we think may be caused by the Lupus cloud. Our analysis also indicates that the observed visual extinction in NGC 6124 is caused by the presence of three different absorption sheets located between the Sun and NGC 6124. The values of the internal dispersion of the polarization (ΔPV ~ 1.3 per cent) and of the colour excess (ΔE(B - V) ~ 0.29 mag) for the members of NGC 6124 seem to be compatible with the presence of an intracluster dust component. Only six stars exhibit some evidence of intrinsic polarization. Our work also shows that polarimetry provides an excellent tool to distinguish between member and non-member stars of a cluster. Based on observations obtained at Complejo Astronómico El Leoncito (CASLEO), operated under agreement between the CONICET and the National Universities of La Plata, Córdoba, and San Juan, Argentina. E-mail: cfeinstein@fcaglp.unlp.edu.ar (CF)

  8. Spectroscopic orbits of two short-period early-type binaries using two-dimensional cross-correlations

    Science.gov (United States)

    González, J. F.; Lapasset, E.

    2003-06-01

    We apply the two-dimensional cross-correlation technique TODCOR to derive spectroscopic orbits for the two B-type double-lined spectroscopic binaries HD 66066A and HD 315031, previously mentioned as blue straggler candidates of the open clusters NGC 2516 and NGC 6530, respectively. Reliable radial velocities for both components are measured even for orbital phases for which the separation between the spectral lines are about 0.5 times the quadratic sum of the full-width at half-maximum of the lines. Both binaries have circular orbits and the orbital periods are 1.67 and 1.38 days for HD 66066A and HD 315031, respectively. We calculate minimum masses with errors of 3-5% and obtain the projected radii from the line widths. We derive absolute stellar parameters which are consistent with the age and distance of the clusters. Both binary systems are formed by main-sequence stars and it is expected that they will experience mass-transfer between their components before the end of the core H-burning stage. HD 315031 is likely a triple system as suggested by the variation of the center-of-mass velocity. The observations presented here were obtained at the Complejo Astronómico El Leoncito (CASLEO), which is operated under agreement between the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina (CONICET) and the National Universities of La Plata, Córdoba and San Juan.

  9. Optical multicolor polarization observations in the region of the open cluster NGC 5749

    Science.gov (United States)

    Vergne, M. M.; Feinstein, C.; Martínez, R.

    2007-02-01

    We present (UBVRI ) multicolor linear polarimetric data for 31 of the brightest stars in the area of the open cluster NGC 5749 considered to study the properties of the interstellar medium (ISM) towards the cluster. Our data yield a mean polarization percentage of PV ˜ 1.7%, close to the polarization value produced by the ISM with normal efficiency (P(%)=3.5 {E(B-V)}0.8) for a mean color excess of EB-V=0.42. The mean angle of polarization vectors, θ=74°, agrees quite well with the expected angle produced by dust particles aligned in the direction of the galactic disk (and the magnetic field) in the region. Our analysis indicates that the visual absorption affecting the stars in NGC 5749 is partially produced by a dust layer located up to 300 pc from the Sun and also by a second layer of dust closer to the cluster (located at least at 700 pc). The observed photometry and our polarization data are consistent with the existence of dust within the cluster. We also show in this work how polarimetry could be an excellent technique for identifying nonmember stars. Based on observations obtained at Complejo Astronómico El Leoncito (CASLEO), operated under agreement between the CONICET and the National Universities of La Plata, Córdoba, and San Juan, Argentina. Table 1 is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/462/621

  10. 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)].

  11. Discovery of a [WO] central star in the planetary nebula Th 2-A

    Science.gov (United States)

    Weidmann, W. A.; Gamen, R.; Díaz, R. J.; Niemela, V. S.

    2008-09-01

    Context: About 2500 planetary nebulae are known in our Galaxy but only 224 have central stars with reported spectral types in the Strasbourg-ESO Catalogue of Galactic Planetary Nebulae (Acker et al. 1992; Acker et al. 1996). Aims: We have started an observational program aiming to increase the number of PN central stars with spectral classification. Methods: By means of spectroscopy and high resolution imaging, we identify the position and true nature of the central star. We carried out low resolution spectroscopic observations at CASLEO telescope, complemented with medium resolution spectroscopy performed at Gemini South and Magellan telescopes. Results: As a first outcome of this survey, we present for the first time the spectra of the central star of the PN Th 2-A. These spectra show emission lines of ionized C and O, typical in Wolf-Rayet stars. Conclusions: We identify the position of that central star, which is not the brightest one of the visual central pair. We classify it as of type [WO 3]pec, which is consistent with the high excitation and dynamical age of the nebula. Based on data collected at (i) the Complejo Astronómico El Leoncito (CASLEO), which is operated under agreement between the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina y Universidades Nacionales de La Plata, Córdoba y San Juan, Argentina; (ii) the 6.5 m Magellan Telescopes at Las Campanas Observatory, Chile; (iii) the 8 m Gemini South Telescope, Chile.

  12. 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.

  13. 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

  14. 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).

  15. 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.

  16. 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).

  17. 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).

  18. 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.

  19. 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.

  20. Exploring extrasolar worlds: from gas giants to terrestrial habitable planets.

    Science.gov (United States)

    Tinetti, Giovanna; Griffith, Caitlin A; Swain, Mark R; Deroo, Pieter; Beaulieu, Jean Philippe; Vasisht, Gautam; Kipping, David; Waldmann, Ingo; Tennyson, Jonathan; Barber, Robert J; Bouwman, Jeroen; Allard, Nicole; Brown, Linda R

    2010-01-01

    Almost 500 extrasolar planets have been found since the discovery of 51 Peg b by Mayor and Queloz in 1995. The traditional field of planetology has thus expanded its frontiers to include planetary environments not represented in our Solar System. We expect that in the next five years space missions (Corot, Kepler and GAIA) or ground-based detection techniques will both increase exponentially the number of new planets discovered and lower the present limit of a approximately 1.9 Earth-mass object [e.g. Mayor et al., Astron. Astrophys., 2009, 507, 487]. While the search for an Earth-twin orbiting a Sun-twin has been one of the major goals pursued by the exoplanet community in the past years, the possibility of sounding the atmospheric composition and structure of an increasing sample of exoplanets with current telescopes has opened new opportunities, unthinkable just a few years ago. As a result, it is possible now not only to determine the orbital characteristics of the new bodies, but moreover to study the exotic environments that lie tens of parsecs away from us. The analysis of the starlight not intercepted by the thin atmospheric limb of its planetary companion (transit spectroscopy), or of the light emitted/reflected by the exoplanet itself, will guide our understanding of the atmospheres and the surfaces of these extrasolar worlds in the next few years. Preliminary results obtained by interpreting current atmospheric observations of transiting gas giants and Neptunes are presented. While the full characterisation of an Earth-twin might requires a technological leap, our understanding of large terrestrial planets (so called super-Earths) orbiting bright, later-type stars is within reach by current space and ground telescopes.

  1. Looking for blazars in a sample of unidentified high-energy emitting Fermi sources

    Science.gov (United States)

    Marchesini, E. J.; Masetti, N.; Chavushyan, V.; Cellone, S. A.; Andruchow, I.; Bassani, L.; Bazzano, A.; Jiménez-Bailón, E.; Landi, R.; Malizia, A.; Palazzi, E.; Patiño-Álvarez, V.; Rodríguez-Castillo, G. A.; Stephen, J. B.; Ubertini, P.

    2016-11-01

    Context. Based on their overwhelming dominance among associated Fermi γ-ray catalogue sources, it is expected that a large fraction of the unidentified Fermi objects are blazars. Through crossmatching between the positions of unidentified γ-ray sources from the First Fermi Catalog of γ-ray sources emitting above 10 GeV (1FHL) and the ROSAT and Swift/XRT catalogues of X-ray objects and between pointed XRT observations, a sample of 36 potential associations was found in previous works with less than 15 arcsec of positional offset. One-third of them have recently been classified; the remainder, though believed to belong to the blazar class, still lack spectroscopic classifications. Aims: We study the optical spectrum of the putative counterparts of these unidentified gamma-ray sources in order to find their redshifts and to determine their nature and main spectral characteristics. Methods: An observational campaign was carried out on the putative counterparts of 13 1FHL sources using medium-resolution optical spectroscopy from the Osservatorio Astronomico di Bologna in Loiano, Italy; the Telescopio Nazionale Galileo and the Nordic Optical Telescope, both in the Canary Islands, Spain; and the Observatorio Astronómico Nacional San Pedro Mártir in Baja California, Mexico. Results: We were able to classify 14 new objects based on their continuum shapes and spectral features. Conclusions: Twelve new blazars were found, along with one new quasar and one new narrow line Seyfert 1 (NLS1) to be potentially associated with the 1FHL sources of our sample. Redshifts or lower limits were obtained when possible alongside central black hole mass and luminosity estimates for the NLS1 and the quasar.

  2. 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.

  3. 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.

  4. Astronomical elements in the religious and funerary world of the ancient Iberians

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    Esteban, César

    2002-12-01

    Full Text Available We present an archaeoastronomical study of 16 sacred and funerary Iberian sites. The work is based on the analysis of the orientation of architectural structures as well as the horizon surrounding each site. Seven of the sites surveyed (44% of them show relevant astronomical relations, mainly to the sunrise or sunset at the equinoxes. We find that most of the iberian sacred buildings not dedicated to cults of domestic character are oriented to the part of the horizon where the sunrise (or moonrise takes place. This pattern of orientations is similar to those shown by Greek, pre- Roman African and perhaps Phoenician and Punic temples, and definetively different to Roman and Etruscan patterns.

    Se presenta un análisis arqueoastronómico de la orientación de las estructuras arquitectónicas así como del horizonte que rodea a 16 yacimientos ibéricos de carácter religioso y funerario. Siete de los lugares estudiados (un 44% presentan relaciones astronómicas relevantes, principalmente con el orto u ocaso solar en los equinoccios. Por otra parte, se obtiene que la mayoría de los edificios de culto ibéricos no domésticos se encuentran orientados hacia la zona del horizonte donde se producen los ortos del sol (o la luna. Este patrón de orientaciones es similar al mostrado por los templos griegos, los africanos prerromanos y quizás también los púnicos y fenicios, pero diferente al romano y al etrusco.

  5. Cycles of time in the Iberian culture: the astronomical orientation of the temple of El Tossal de Sant Miquel de Llíria

    Directory of Open Access Journals (Sweden)

    Esteban, César

    2006-06-01

    Full Text Available We present an archaeoastronomical study of the temple of the Iberian settlement of El Tossal de Sant Miquel de Llíria (València. We find that the major axis of the building is oriented very close to the east-west cardinal axis. The entrance of the temple is pointing towards an outstanding mountain on the eastern horizon, where the sunrise around the equinoxes takes place. On the other hand, the absence of other constructions just in front of the cultic building seems to support the inference that the astronomical relation was intentional, because it would permit the observation of the sunrise from the temple. The existence of other nearby Iberian sanctuaries showing similar relations with the equinoxes (or a date very close to them strongly supports the importance of these solar dates in the Iberian ritual.

    Presentamos un estudio arqueoastronómico del templo del poblado ibérico del Tossal de Sant Miquel de Llíria (Valencia. Encontramos que el eje mayor del edificio se encuentra orientado casi paralelo al eje cardinal este-oeste, con su entrada apuntando hacia una montaña singular del horizonte oriental donde se produce el orto solar alrededor de los equinoccios. Por otra parte, la ausencia de construcciones justo enfrente de la entrada del templo parece apoyar la intencionalidad de dicha relación astronómica, pues permitiría preservar la observación del fenómeno desde el edificio. La existencia de otros yacimientos ibéricos cercanos donde se han encontrado relaciones similares con los equinoccios (o una fecha muy cercana a éstos apunta, cada vez más claramente, hacia la idea de un especial protagonismo del paso del sol por los equinoccios en el calendario ritual ibérico.

  6. The Problem of Longitude in the 18th Century: Jorge Juan, Antonio de Ulloa and the Expedition of the Paris Academy of Sciences to the Kingdom of Peru

    Science.gov (United States)

    Gutiérrez, Manuel Pérez

    2015-05-01

    Jorge Juan and Antonio de Ulloa, naval officers of the Spanish Navy in the Midshipmen's Royal Academy were appointed to take part in one of the most important scientific expeditions of the 18th century. The question of the shape of the Earth, of vital importance for navigation, was solved by the Paris Academy of Sciences by request of Louis XV of France in 1735. The aim was to determine the form of the ellipsoid that Newton had described in the 17th century for any spherical and homogeneous body in rotation about an axis. Two expeditions were prepared for the geodetic measures of meridian arc both in high latitudes (Lapland, Finland) and in the equatorial zone (the Kingdom of Peru); Pierre Louis Maupertuis took charge of the northern expedition whereas the second one was charged to La Condamine, along with Jorge Juan and Antonio de Ulloa. The results obtained by the Spaniards were gathered in a publication: Observaciones astronómicas y físicas hechas en los Reinos del Perú. In it, they dedicate a chapter to the determination of astronomic longitude with the only technology that was providing certain precision at the moment: the simultaneous observation of the same astronomic phenomenon in two different places. Specifically, they explain in detail in Book III: Las Observaciones de la Inmersiones y Emersiones de los satélites de Júpiter, como asimismo de los eclipses de Luna; de las cuales de deduce la Longitud de los Lugares, incluyendo las correcciones a efectuar por la variación de la declinación diaria del Sol.

  7. 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

  8. Chinese astronomy as an indicator of technological development

    Directory of Open Access Journals (Sweden)

    Josep Martí-Ribas

    2013-02-01

    Full Text Available Este artículo ilustra la cerrada relación entre el desarrollo tecnológico y el progreso científico. Ejemplos de estas conexiones se pueden ver en el caso de estudio de la astronomía china. Aspectos remarcables en el historial de las contribuciones al conocimiento de los cuerpos celestes, el papel de China en la moderna astronomía y el papel de los astrónomos en tiempos recientes. Únicamente en las últimas décadas China ha iniciado su desarrollo en proyectos astronómicos (telescopios ópticos, estaciones de radio…. Estos avances, y su uso, permiten excelentes capacidades para estudiar la astronomía a través de diferentes ventanas. Además, los astrónomos chinos son miembros activos a través de diversas colaboraciones internacionales.Palabras clave: China, astronomía, tecnología, telescopios._______________________Abstract:This paper illustrated the close relationship between technology development and progress in science. Examples of this connection are discussed using Chinese Astronomy as a study case. Despite remarkable historical contributions to the knowledge of celestial bodies, the role of China in modern Astronomy and Astrophysics did not start until relatively recent times. Only in the last decades has China started to develop impressive astronomical projects (optical telescopes, interferometric radio networks, Cherenkov detector arrays, etc. in parallel with the country's growth.These facilities provide, or will soon provide, excellent capabilities for observational astronomy in different windows of the electromagnetic spectrum. In addition, Chinese astronomers are currently active members of the major international astronomical collaborations.Keywords: China, astronomy, technology, telescopes.

  9. THE ESO EXTREMELY LARGE TELESCOPE

    Directory of Open Access Journals (Sweden)

    J. Melnick

    2011-01-01

    Full Text Available Los instrumentos robóticos utilizados en campañas de evaluación de sitios generan una gran cantidad de información, esencialmente acerca de todos los parámentros relevantes de la atmósfera. Comenzando por suposiciones relativamente genéricas, es posible capturar esta riqueza de información en una figura sencilla de mérito para cada sitio, lo cual simplifica algunas de las etapas del proceso de evaluación de sitio. Esta contribución presenta dos formalismos diferentes que fueron usados para evaluar la función de mérito de selección de sitio para el E-ELT. Ambos formalismos recaen en suposiciones acerca de las formas en que se usará el telescopio -los modos científicos de operación- pero mientras un algoritmo calcula las figuras de mérito promediadas sobre todo el tiempo de la campaña de evaluación de sitio (típicamente 2 años, el otro explora la variabilidad de las condiciones de observación durante la noche, y de noche a noche durante la campaña. Se encontró que en general, los dos métodos arrojan resultados diferentes, señalando la importancia de incluir la variabilidad como un parámetro fundamental para caracterizar los sitios astronómicos para telescopios grandes operados en modo de programación de cola. Sin embargo, los dos mejores sitios potenciales para E-ELT están clasificados como mejores por ambos métodos.

  10. 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.

  11. 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)

  12. 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.

  13. 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.

  14. Flux-Velocity Relation for H2 Outflows

    Science.gov (United States)

    Salas, Luis; Cruz-González, Irene

    2002-06-01

    We present an analysis of velocity-resolved near-IR molecular hydrogen observations of a variety of protostellar outflows with very different energetics, degrees of collimation, and morphologies. Observations in the 2.12 μm line of H2 were obtained using an IR Fabry-Pérot interferometer with a spectral resolution of 23 km s-1. The integrated flux-velocity diagrams for each outflow show a flat spectrum for low velocities followed by a decreasing power law dF/dv~vγ, with γ between -1.8 and -2.6, for velocities higher than a clearly defined break velocity at 2-17 km s-1. Contrary to shock model predictions, it is shown that the H2 intensity is constant with velocity. We argue that the flux-velocity relation can then be interpreted as a mass-velocity relation, in striking similarity to the power-law mass spectra observed in CO outflows. By comparing H2 and CO mass-velocity spectra, it is shown that there is a velocity regime in which both molecules coexist and produce similar γ-values. Evolution effects in outflows appear as a correlation between outflow length and γ as outflows age, the spectra becomes steeper. Our results support a common physical origin for both CO and H2 emission and a strong association between the molecular outflows traced in each molecule. Based on observations obtained at the Observatorio Astronómico Nacional at San Pedro Mártir, Mexico.

  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

    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.

  16. Gravitational wave transient signal emission via Ekman pumping in neutron stars during post-glitch relaxation phase

    Science.gov (United States)

    Singh, Avneet

    2017-01-01

    Glitches in the rotational frequency of a spinning neutron star could be promising sources of gravitational wave signals lasting between a few microseconds to a few weeks. The emitted signals and their properties depend upon the internal properties of the neutron star. In neutron stars, the most important physical properties of the fluid core are the viscosity of the fluid, the stratification of flow in the equilibrium state, and the adiabatic sound speed. Such models were previously studied [C. A. van Eysden and A. Melatos, Classical Quantum Gravity 25, 225020 (2008, 10.1088/0264-9381/25/22/225020); M. F. Bennett, C. A. van Eysden, and A. Melatos, Mon. Not. R. Astron. Soc. 409, 1705 (2010), 10.1111/j.1365-2966.2010.17416.x] following simple assumptions on all contributing factors, in which the post-glitch relaxation phase could be driven by the well-known process of Ekman pumping [G. Walin, J. Fluid Mech. 36, 289 (1969, 10.1017/S0022112069001662); M. Abney and R. I. Epstein, J. Fluid Mech. 312, 327 (1996), 10.1017/S0022112096002030]. We explore the hydrodynamic properties of the flow of fluid during this phase following more relaxed assumptions on the stratification of flow and the pressure-density gradients within the neutron star than previously studied. We calculate the time scales of duration as well as the amplitudes of the resulting gravitational wave signals, and we detail their dependence on the physical properties of the fluid core. We find that it is possible for the neutron star to emit gravitational wave signals in a wide range of decay time scales and within the detection sensitivity of aLIGO for selected domains of physical parameters.

  17. Determinacion de Caracteristicas Opticas del Telescopio OAN150

    Science.gov (United States)

    Galan, M. J.; Cobos, F. J.

    1987-05-01

    En el Observatorio de Calar Alto, en Almería, España, está ubicado un telescopio de 15O-cms de diámetro -construído por REOSC- perteneciente al Observatorio Astronómico Nacional, con sede en Madrid, España. La infraestructura técnica del OAN ha sido tradicionalmente débil y actualmente se está haciendo un esfuerzo por fortalecerla. Existe una información muy limitada del telescopio en general; de su óptica en particular se conocían los valores de los parámetros principales pero sin saber si éstos corresponden a valores teóricos ó de construcción. Por ello se consideró necesario iniciar una investigación para conocer en detalle los valores reales de las componentes ópticas del telescopio, obteniéndose algunos resultados de interés. El primario del telescopio OANl5O es aproximadamente F/3 y el siste ma en su conjunto es F/8.2, con su sistema corrector de campo. En términos generales, la imagen es satisfactoria en todo el campo y, sin sistema corrector, la imagen axial también es buena. En un futuro muy cercano se piensa diseñar instrumentación adicional para este telescopio. Conocer con mayor precisión sus características puede ser de gran utilidad para tal fin, pues se efectúan los cálculos considerando conjuntamente al telescopio y al instrumento.

  18. Constraining the Angular Momentum of the Sun with Planetary Orbital Motions and General Relativity

    Science.gov (United States)

    Iorio, L.

    2012-12-01

    The angular momentum of a star is an important astrophysical quantity related to its internal structure, formation, and evolution. Helioseismology yields S_{⊙}= 1.92×10^{41} kg m^{2 s^{-1}} for the angular momentum of the Sun. We show how it should be possible to constrain it in a near future by using the gravitomagnetic Lense-Thirring effect predicted by General Relativity for the orbit of a test particle moving around a central rotating body. We also discuss the present-day situation in view of the latest determinations of the supplementary perihelion precession [InlineEquation not available: see fulltext.] of Mercury. A fit by Fienga et al. ( Celestial Mech. Dynamical Astron. 111, 363, 2011) of the dynamical models of several standard forces acting on the planets of the solar system to a long data record yielded [InlineEquation not available: see fulltext.] milliarcseconds per century. The modeled forces did not include the Lense-Thirring effect itself, which is expected to be as large as [InlineEquation not available: see fulltext.] from helioseismology-based values of S ⊙. By assuming the validity of General Relativity, from its theoretical prediction for the gravitomagnetic perihelion precession of Mercury, one can straightforwardly infer S_{⊙}≤0.95×10^{41} kg m^{2 s^{-1}}. It disagrees with the currently available values from helioseismology. Possible sources for the present discrepancy are examined. Given the current level of accuracy in the Mercury ephemerides, the gravitomagnetic force of the Sun should be included in their force models. MESSENGER, in orbit around Mercury since March 2011, will collect science data until 2013, while BepiColombo, to be launched in 2015, should reach Mercury in 2022 for a year-long science phase: the analysis of their data will be important in effectively constraining S ⊙ in about a decade or, perhaps, even less.

  19. 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.

  20. 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.

  1. Studies of cosmic plasma using radioastron VLBI observations of giant pulses of the pulsar B0531+21

    Science.gov (United States)

    Rudnitskii, A. G.; Karuppusamy, R.; Popov, M. V.; Soglasnov, V. A.

    2016-02-01

    The structure of the interstellar plasma in the direction of the pulsar in the Crab Nebula is studied using several sets of space-VLBI observations obtained with networks of ground telescopes and the RadioAstron space antenna at 18 and 92 cm. Six observing sessions spanning two years are analyzed. Giant pulses are used to probe the cosmic plasma, making it possible to measure the scattering parameters without averaging. More than 4000 giant pulses were detected. The interferometer responses (visibility functions) on ground and ground-space baselines are analyzed. On the ground baselines, the visibility function as a function of delay is dominated by a narrow feature at zero delay with a width of δ τ ~ 1/B, where B is the receiver bandwidth. This is typical for compact continuum sources. On the ground-space baselines, the visibility function contains a set of features superposed on each other and distributed within a certain interval of delays, which we identify with the scattering time for the interfering rays τ. The amplitude of the visibility function on ground baselines falls with increasing baseline; the scattering disk is partially resolved at 18 cmand fully resolved at 92 cm. Estimates of the scattering angle ? give 0.5-1.3mas at 18 cm and 14.0 mas at 92 cm. The measured values of ? and τ are compared to estimate the distance from the source to the effective scattering screen, which is found at various epochs to be located at distances from 0.33 to 0.96 of the distance from the observer to the pulsar, about 2 kpc. The screen is close to the Crab Nebula at epochs of strong scattering, confirming that scattering on inhomogeneities in the plasma in the vicinity of the nebula itself dominates at these epochs.

  2. Properties of extra-planar H I clouds in the outer part of the Milky Way

    Science.gov (United States)

    Dedes, L.; Kalberla, P. W. M.

    2010-01-01

    Context. There is mounting evidence for an extra-planar gas layer around the Milky Way disk, similar to the anomalous H I gas detected in a few other galaxies. As much as 10% of the gas may be in this phase. Aims: We analyze H I clouds located in the disk-halo interface outside the solar circle to probe the properties of the extra-planar H I gas, which is following Galactic rotation. Methods: We use the Leiden/Argentine/Bonn (LAB) 21-cm line survey to search for H I clouds which take part in the rotation of the Galactic plane, but are located above the disk layer. Selected regions are mapped with the Effelsberg 100-m telescope. Two of the H I halo clouds are studied in detail for their small scale structure using the Westerbork Synthesis Radio Telescope (WSRT)[The Westerbork Synthesis Radio Telescope is operated by ASTRON (Netherlands Foundation for Research in Astronomy) with support from the Netherlands Foundation for Scientific Research NWO.] and the NRAO Very Large Array (VLA)[The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.]. Results: Data from the 100 m telescope allow for the parameterization of 25 distinct H I halo clouds at Galactocentric radii 10 kpc 1.3 cm-3, masses up to 24 M⊙, and are on average in pressure equilibrium with the surrounding envelopes. Pressures and densities fall within the expectations from theoretical phase diagrams (P vs. ). The H I cores tend to be unstable if one assumes a thermally bistable medium, but are in better agreement with models that predict thermal fragmentation driven by a turbulent flow.

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

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    Xiang-Shun Hu

    Full Text Available 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

  4. 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.

  5. 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.

  6. 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.

  7. A possible long-term activity cycle for ι Horologii: First results from SPI-HKα project

    Science.gov (United States)

    Flores, Matías G.; Buccino, Andrea P.; Saffe, Carlos E.; Mauas, Pablo J. D.

    2017-02-01

    In order to detect stellar activity cycles and study possible star-planet interactions (SPIs), we have been developing the HKα and SPI-HKα projects since 1999 and 2012 respectively. In this work, we present preliminary results of possible SPIs from studies of chromospheric activity and look for possible correlations between stellar activity and stellar/planetary parameters. We find that for stars with a similar Teff, stellar activity increases with the mass of the planet, similar to results from previous works. However, stellar ages can also play a role, and a larger stellar sample is needed to verify these trends. We also note that some of these stars present a remarkably high level of chromospheric activity, comparable even with RSCvn or BY Dra active stars. In addition, we do not observe any correlation between stellar activity and semi-major axis. We present the first long-term activity study of the star ι Horologii, a young solar-type star that hosts a non-transiting Jovian planet and exhibits a high activity level. We analysed our own spectra, obtained between 2002 and 2015, in conjunction with public HARPS (High Accuracy Radial velocity Planet Searcher) observations. We calculated the Ca II indexes derived from the 987 Complejo Astronómico El Leoncito (CASLEO) and HARPS spectra and converted them to the Mt Wilson scale. We found a long-term activity cycle of ˜5 yr which fits the active sequence of Böhm-Vitense. The amplitude of this longer cycle is irregular, as was also observed for the shorter cycle. This phenomenon could be attributable to an antisymmetric distribution of active regions on the stellar surface.

  8. 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.

  9. 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.

  10. Expo 70 - Osaka, Japón

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    Editorial, Equipo

    1970-06-01

    Full Text Available The following pavillions at the Expo-70 in Osaka are outstanding. The West German Exhibit, with a structure reminiscent of an astronomical observatory. The U.R.R.S. Pavillion, which is 109 m high, and has a tubular support. The Motor Car Industry Display, which involves two units and a tent like roof. The Festival Palace, within the representative zone of the Exhibition, and houses the official ceremonies in honour of the participating nations. The Tashida IHI Pavillion, whose structure includes the use of 1,338 interconnected tetrapods. The Takara Group Display, which is an abstract concept, consisting of a large number of cube space forms. The firm Takenaka Komuten Co. Ltd. has taken a very active part in the construction of 28 buildings, both Japanese and foreign.Destacan en la EXPO-70 los siguientes pabellones: el pabellón de la Alemania Occidental, con su estructura en forma de cúpula para observaciones astronómicas; el de la U.R.S.S., de 109 m de altura y estructura tubular; el de la Industria Automovilística, que consta de dos unidades y presenta una cubierta en forma de tienda de campaña; el palacio de Festivales, que forma parte de la zona representativa de la exposición; en él se desarrollan los actos dedicados a las naciones participantes; el pabellón Toshiba IHI, en cuya estructura se emplearon un total de 1.338 tetrápodos ensamblados; el pabellón del grupo Takara, diseñado con una concepción abstracta —a base de cubos—. La empresa «Takenaka Komuten, Co. Ltd.», ha intervenido eficazmente en la construcción de 28 pabellones, japoneses y extranjeros.

  11. 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.

  12. 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.

  13. 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.

  14. Where Is Apophis?

    Science.gov (United States)

    Tholen, David J.; Bernardi, F.; Micheli, M.

    2008-09-01

    Between 2006 March, when the last observations of (99942) Apophis were obtained by others, and 2008 January, we have acquired over 200 additional observations on 27 different nights, with one of the goals being to improve the orbit sufficiently to eliminate the 2036 impact possibility. Rather surprisingly, the astrometry shows a systematic offset of about 0.2 arcsec to the north of the ephemeris position. During the time spanned by these observations, Apophis made nearly two complete trips around the sky, thus sampling a wide variety of background reference fields. We have been studying this problem, which has implications for the impact probability calculations. Because of the small solar elongations at which these observations were made, we investigated relativistic deflection of the light from background reference stars. The displacement is primarily in ecliptic longitude for a source located near the ecliptic, with the declination component being insufficient to explain the observed offset. Because the observations were also made at large zenith distances and often unfiltered, we investigated the effect of differential refraction. Although considerably larger than the relativistic effects, differential refraction also appears to be insufficient to explain the observed offset. Our attention is currently focused on potential systematic errors in declination in our astrometric reference catalog of choice, namely the USNO-B1.0 catalog. A comparison of positions for 64 ICRF sources that appear in the USNO-B1.0 catalog by da Silva Neto (Astron. Astrophys. 429, 739-745, 2005) has shown an average declination offset of +0.116 arcsec, about half of what we see in the Apophis data, with 45 of the 64 sources showing positive differences. Systematically positive declination offsets are also seen for other asteroids, suggesting that the problem is not unique to Apophis.

  15. Massive identification of asteroids in three-body resonances

    Science.gov (United States)

    Smirnov, Evgeny A.; Shevchenko, Ivan I.

    2013-01-01

    An essential role in the asteroidal dynamics is played by the mean motion resonances. Two-body planet-asteroid resonances are widely known, due to the Kirkwood gaps. Besides, so-called three-body mean motion resonances exist, in which an asteroid and two planets participate. Identification of asteroids in three-body (namely, Jupiter-Saturn-asteroid) resonances was initially accomplished by Nesvorný and Morbidelli (Nesvorný D., Morbidelli, A. [1998]. Astron. J. 116, 3029-3037), who, by means of visual analysis of the time behaviour of resonant arguments, found 255 asteroids to reside in such resonances. We develop specialized algorithms and software for massive automatic identification of asteroids in the three-body, as well as two-body, resonances of arbitrary order, by means of automatic analysis of the time behaviour of resonant arguments. In the computation of orbits, all essential perturbations are taken into account. We integrate the asteroidal orbits on the time interval of 100,000 yr and identify main-belt asteroids in the three-body Jupiter-Saturn-asteroid resonances up to the 6th order inclusive, and in the two-body Jupiter-asteroid resonances up to the 9th order inclusive, in the set of ˜250,000 objects from the "Asteroids - Dynamic Site" (AstDyS) database. The percentages of resonant objects, including extrapolations for higher-order resonances, are determined. In particular, the observed fraction of pure-resonant asteroids (those exhibiting resonant libration on the whole interval of integration) in the three-body resonances up to the 6th order inclusive is ≈0.9% of the whole set; and, using a higher-order extrapolation, the actual total fraction of pure-resonant asteroids in the three-body resonances of all orders is estimated as ≈1.1% of the whole set.

  16. The 2010, February 19 stellar occultation by Varuna

    Science.gov (United States)

    Sicardy, Bruno; Colas, F.; Maquet, L.; Vachier, F.; Doressoundiram, A.; Roques, F.; Widemann, T.; Ortiz, J.; Assafin, M.; Braga-Ribas, F.; Camargo, J. I. B.; Vieira-Martins, R.; Andrei, A.; da Silva Neto, D.; Behrend, R.; Hund, F.; Hauser, M.; Wagner, S.; Slotegraaf, A.; Willasch, D.; Costa, M. de Jesus; Melo Sousa, P.; Faustino, E.; Prazeres, A.; Machado, S.; Dias do Nascimento, J.; Souza Barreto, E.; Amorim, A.; da Rocha Poppe, P.; Pereira, M. Geraldete; Jacques, C.; Loureiro Giacchini, B.; Collucci, A.; Ferreira da Costa, W.; Martins de Morais, V.

    2010-10-01

    On 2010, February 19, Varuna occulted UCAC2 star 41014042, as seen from regions in southern Africa and north-eastern Brazil. No occultation was observed neither from the station deployed in South Africa, nor from three other stations in Namibia. Out of twelve stations deployed in Brazil, seven had clouds or instrument malfunctions. Three were negative, one possibly positive (visual) is still being analyzed, and one is definitely positive from Sao Luis (CCD). This makes Varuna the most remote solar system object observed to date through a stellar occultation, with a geocentric distance of 6.4 billions km. The Sao Luis occultation has a duration of 52.5 +/- 0.5 sec, corresponding to a chord length of 1003 +/- 9 km projected in the plane of the sky. No atmospheric signature is apparent in the light curve. Since the closest observation to Sao Luis is negative at a transversal distance of 225 km (Quixada, CCD), a significantly elongated shape is required for Varuna. We will discuss our results in view of current independent estimations of Varuna's diameter combining IR thermal and visible data, with a typical value of 1050 km +/- 200 km (Lellouch et al. 2002, Stansberry et al., 2008). We will also discuss the fact that the occultation occurred near Varuna's maximum brightness along its 6.4 hr rotational (0.4-mag amplitude) light curve. Thus Varuna was observed at maximum apparent surface area, which also corresponds to maximum apparent oblateness for an ellipsoidal shape. Lellouch et al, Astron. Astrophys. 391, 1133-1139 (2002). Stansberry et al., in The Solar System beyond Neptune (eds Barucci, M. A.,Boehnhardt, H., Cruikshank, D. P. & Morbidelli, A.) 161-179 (Univ. Arizona Press, 2008). This work is partially supported by french ANR 08-BLAN-0177 "Beyond Neptune".

  17. Exoplanets' atmospheres: comparing and separating different sources of disequilibria

    Science.gov (United States)

    Simoncini, Eugenio; Brucato, John Robert

    The atmosphere of the only known (till nowadays) inhabited planet is characterized by a unique disequilibrium state in terms of chemical composition. Studying this state of disequilibrium is important for its potential role in the detection of life on other suitable planets [1][2][3]. However, different processes are able to produce chemical disequilibrium in planetary atmospheres, thus a tool to compute the extent of disequilibrium is needed. We developed a methodology to calculate the extent of atmospheric chemical disequilibrium [3][4]. A new computational framework called KROME has been applied to atmospheric models in order to give a correct computation of reactionś kinetics [5]. This methodology allows to compute, for models of different planets, the extent of disequilibrium due to several processes, such as fast vertical mixing, eddy diffusion, photochemistry, extremely diverse atmospheres due to tidal effect. Using Earth’s models, we also infer the potential extension of the effect of a biosphere on disequilibrium. Our results provide a comprehensive analysis of atmospheric disequilibrium for rocky planets, which can be also used for the detection of habitable conditions on farther planetary bodies. [1] Lovelock, J. E.: A physical basis for life detection experiments, Nature, 207, 568 (1965) [2] Kleidon, A., Physics of Life Reviews, 7, 424 (2010) [3] Simoncini E., Grassi T., Disequilibrium in planetary atmospheres: a first calculation for Earth using KROME, submitted to OLEB. [4] Kondepudi D., Prigogine I., Modern Thermodynamics, Wiley (1996) [5] Grassi, T., Bovino, S., Schleicher, D. R. G., Prieto, J., Seifried, D., Simoncini, E., Gianturco, F. A., in press on Mon. Not. R. Astron. Soc. MN-13-2848-MJ.R1

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. Luces y arquitectura en las iglesias coloniales de la Nueva España y del Perú

    Directory of Open Access Journals (Sweden)

    Robert A. Benfer

    2013-05-01

    Full Text Available En esta investigación, les presento los resultados de un estudio sobre las iglesias coloniales de Nueva España y el Perú, que muestran cuál fue el propósito de los primeros arquitectos. Estas construcciones fueron diseñadas de tal manera que los haces de luz, especialmente los procedentes de las ventanas de la cúpula, marcasen días de gran importancia astronómica y eclesiástica. La orientación de las iglesias variaba según las ciudades (que generalmente estaban alineadas con los puntos cardinales, normalmente de Este a Oeste mientras que las misiones rurales estaban orientadas normalmente hacia los solsticios. En muchas ocasiones, la planeación de las ciudades seguía la orientación de las iglesias –aunque hay excepciones–, y algunos centros coloniales todavía conservan una orientación equinoccial o solsticial.Hasta que Rubén Mendoza lo redescubrió en las misiones de California (2005, 2009, ni laicos y clérigos tenían noticia de este fenómeno. El trabajo que les presento aquí extiende su alcance desde las iglesias franciscanas de California hasta las de Texas de la misma orden, llegando también a las iglesias dominicas de México y Perú. Esta investigación muestra cómo el diseño de las iglesias coloniales está pensado para que la trayectoria de los rayos de luz marcara dentro de las iglesias el equinoccio, el solsticio y el día de cruce de cuartos (a mitad de camino entre los otros dos.

  3. On Global Magnetic ``Monopoly'' Near Solar Cycle Maximums

    Science.gov (United States)

    Kryvodubskyj, V.

    During last maximums of the solar activity the both poles of the polar magnetic field had the same polarity. Since in the turbulent α Ω -dynamo model the excitation thresholds of the periodic dipole and quadrupole modes of the poloidal madnetic field (PMF) are rather close [Parker E. N.: 1971, Ap.J. V. 164, p. 491] then it is possible that the quadrupole mode may be excited due to variations of physical parameters in a some regions of the solar convection zone (SCZ). The pattern of the excited modes (dipole, quadrupole, octupole, etc.) is determined by the values of wave number of the Parker's dynamo-wave. We calculated these values for the SCZ model by Stix (1989) [Stix M.: 1989, The Sun. Berlin, p. 200] in the vicinity of solar tachocline (a region of strong shear of angular velocity at the base of the SCZ) with using our estimation of the helical turbulence parameter [Krivodubskij V. N.: 1998, Astron. Reports V. 42, No 1, p. 122] and values of the radial gradient of the angular velocity obtained from the newer helioseismic measurements (during rising phase of 23th solar cycle: 1995-1999) [Howe R.,Christensen-Dalsgaard J., Hill F. et al.: 2000, Science. V. 287, p. 2456]. It is found out that at low latitudes dynamo mechanism produces rather the dipole (wave number ≈ -7), the main antisymmetric, relatively to equatorial plane, mode of the PMF; while at the latitudes higher than 50o the conditions are more favourable for exciting of the quadrupole (wave number ≈ +8), the lowest symmetric mode. Arised north-south magnetic structure asymmetry gives an opportunity to explain the space magnetic anomaly of the PMF (``monopoly'') observed near solar cycle maximums.

  4. CALIFA, the Calar Alto Legacy Integral Field Area survey. III. Second public data release

    Science.gov (United States)

    García-Benito, R.; Zibetti, S.; Sánchez, S. F.; Husemann, B.; de Amorim, A. L.; Castillo-Morales, A.; Cid Fernandes, R.; Ellis, S. C.; Falcón-Barroso, J.; Galbany, L.; Gil de Paz, A.; González Delgado, R. M.; Lacerda, E. A. D.; López-Fernandez, R.; de Lorenzo-Cáceres, A.; Lyubenova, M.; Marino, R. A.; Mast, D.; Mendoza, M. A.; Pérez, E.; Vale Asari, N.; Aguerri, J. A. L.; Ascasibar, Y.; Bekerait*error*ė, S.; Bland-Hawthorn, J.; Barrera-Ballesteros, J. K.; Bomans, D. J.; Cano-Díaz, M.; Catalán-Torrecilla, C.; Cortijo, C.; Delgado-Inglada, G.; Demleitner, M.; Dettmar, R.-J.; Díaz, A. I.; Florido, E.; Gallazzi, A.; García-Lorenzo, B.; Gomes, J. M.; Holmes, L.; Iglesias-Páramo, J.; Jahnke, K.; Kalinova, V.; Kehrig, C.; Kennicutt, R. C.; López-Sánchez, Á. R.; Márquez, I.; Masegosa, J.; Meidt, S. E.; Mendez-Abreu, J.; Mollá, M.; Monreal-Ibero, A.; Morisset, C.; del Olmo, A.; Papaderos, P.; Pérez, I.; Quirrenbach, A.; Rosales-Ortega, F. F.; Roth, M. M.; Ruiz-Lara, T.; Sánchez-Blázquez, P.; Sánchez-Menguiano, L.; Singh, R.; Spekkens, K.; Stanishev, V.; Torres-Papaqui, J. P.; van de Ven, G.; Vilchez, J. M.; Walcher, C. J.; Wild, V.; Wisotzki, L.; Ziegler, B.; Alves, J.; Barrado, D.; Quintana, J. M.; Aceituno, J.

    2015-04-01

    This paper describes the Second Public Data Release (DR2) of the Calar Alto Legacy Integral Field Area (CALIFA) survey. The data for 200 objects are made public, including the 100 galaxies of the First Public Data Release (DR1). Data were obtained with the integral-field spectrograph PMAS/PPak mounted on the 3.5 m telescope at the Calar Alto observatory. Two different spectral setups are available for each galaxy, (i) a low-resolution V500 setup covering the wavelength range 3745-7500 Å with a spectral resolution of 6.0 Å (FWHM); and (ii) a medium-resolution V1200 setup covering the wavelength range 3650-4840 Å with a spectral resolution of 2.3 Å (FWHM). The sample covers a redshift range between 0.005 and 0.03, with a wide range of properties in the color-magnitude diagram, stellar mass, ionization conditions, and morphological types. All the cubes in the data release were reduced with the latest pipeline, which includes improvedspectrophotometric calibration, spatial registration, and spatial resolution. The spectrophotometric calibration is better than 6% and the median spatial resolution is 2.̋4. In total, the second data release contains over 1.5 million 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 second data release is available at http://califa.caha.es/DR2

  5. 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.

  6. Comparing binary systems from rotating parent gas structures with different total masses

    Science.gov (United States)

    Arreaga-García, Guillermo

    2017-03-01

    In this paper we continue the investigation reported by Arreaga-Garcia (Rev. Mex. Astron. Astrofís. 52(1):1-15, 2016) concerning the morphology of binary configurations obtained via the collapse of rotating parent gas structures with total masses in the range of MT= 1 to 5 M_{⊙}. Here we extend the mass range and consider the collapse of two uniform gas clumps of MT = 50 and 400 M_{⊙}, so that they also rotate rigidly in such a way that its approximate virial parameter takes the values of 0.5, 1.5, and 2.5 and their collapse is induced initially by implementing an azimuthal mass perturbation. To assess the effects of the total mass of the parent gas structure on the nature of the resulting binary configurations, we also consider the collapse of two cores of MT = 1 and 5 M_{⊙}. We calculate the collapse of all these parent gas structures using three values of the ratio of thermal energy to potential energy, α, and for two values of the mass perturbation amplitude. For most of our models, we next calculate the extreme value of the ratio of rotational energy to potential energy, β, so that a model with a slightly higher β value would no longer collapse. We finally calculate the binary separations, masses and some integral properties of the binary fragments, the αf and βf and present them in terms of the total mass of the parent structure.

  7. 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.

  8. 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.

    2017-02-01

    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.

  9. On the Ratio of Periods of the Fundamental Harmonic and First Overtone of Magnetic Tube Kink Oscillations

    Science.gov (United States)

    Ruderman, M. S.; Petrukhin, N. S.; Pelinovsky, E.

    2016-04-01

    We study kink oscillations of thin magnetic tubes. We assume that the density inside and outside the tube (and possibly also the cross-section radius) can vary along the tube. This variation is assumed to be of such a form that the kink speed is symmetric with respect to the tube centre and varies monotonically from the tube ends to the tube centre. Then we prove a theorem stating that the ratio of periods of the fundamental mode and first overtone is a monotonically increasing function of the ratio of the kink speed at the tube centre and the tube ends. In particular, it follows from this theorem that the period ratio is lower than two when the kink speed increases from the tube ends to its centre, while it is higher than two when the kink speed decreases from the tube ends to its centre. The first case is typical for non-expanding coronal magnetic loops, and the second for prominence threads. We apply the general results to particular problems. First we consider kink oscillations of coronal magnetic loops. We prove that, under reasonable assumptions, the ratio of the fundamental period to the first overtone is lower than two and decreases when the loop size increases. The second problem concerns kink oscillations of prominence threads. We consider three internal density profiles: generalised parabolic, Gaussian, and Lorentzian. Each of these profiles contain the parameter α that is responsible for its sharpness. We calculate the dependence of the period ratio on the ratio of the mean to the maximum density. For all considered values of α we find that a formula relating the period ratio and the ratio of the mean and maximum density suggested by Soler, Goossens, and Ballester ( Astron. Astrophys. 575, A123, 2015) gives a sufficiently good approximation to the exact dependence.

  10. Search for volatiles on icy satellites. I. Europa

    Science.gov (United States)

    Brown, R.H.; Cruikshank, D.P.; Tokunaga, A.T.; Smith, R.G.; Clark, R.N.

    1988-01-01

    New reflectance spectra have been obtained for both the leading and trailing sides of Europa, using the Cooled Grating Array Spectrometer (CGAS) of the NASA Infrared Telescope Facility (IRTF). The spectra are of higher precision than any yet obtained. Spectra of Europa's trailing side (central meridian longitude ???300??) obtained in 1985 show two weak absorptions near 2.2 and 2.3 ??m. Both of these features as well as others are seen in spectra obtained by R. N. Clark, R. B. Singer, P. D. Owensby, and F.P. Fanale (1980a, Bull. Amer. Astron. Soc. 12, 713-714) at similar central meridian longitude. Data obtained with an improved detector array in 1986, however, do not show the absorptions seen in the 1980 and 1985 spectra. It is not clear why the newest data do not show the apparent absorptions seen in previous years, but the suggestion is that either the 1980 and 1985 data are spurious or that the material responsible for the weak absorptions is no longer detectable. Analysis of the 1980 and 1985 data did not reveal any obvious source of systematic error capable of introducing spurious features, but we are skeptical of any explanation that cites transient deposition, movement, and/or destruction of material on Europa's trailing side to account for the nondetection of the features in the 1986 data. If the weak absorptions seen in the 1980 and 1985 data are real, they can be interpreted as indicating the transient spectroscopic presence of a molecular component on Europa's trailing side different from the water ice that is known to be the dominant surface constituent. Further monitoring is required to determine if the apparent absorptions are real. ?? 1988.

  11. Optical polarization observations in Hogg 22 and NGC 6204

    Science.gov (United States)

    Martínez, R.; Vergne, M. M.; Feinstein, C.

    2004-06-01

    We present new (UBVRI) multicolor linear polarimetric data for 22 of the brightest stars in the area of the open clusters Hogg 22 and NGC 6204 to study the properties of the ISM (interstellar medium) toward these clusters and between them. The new data were incorporated in our data set of previous observations (Waldhausen et al. \\cite{waldhausen}), resulting in 28 observed stars in the region. Our data yield for NGC 6204 a mean polarization percentage of Pλ_max˜1.8%, close to the polarization value produced by the ISM with normal efficiency (Pλ_max ˜ 5 EB-V) with a color excess of EB-V =0.51. Meanwhile for Hogg 22, located behind NGC 6204, the mean polarization is Pλ_max˜ 2.15%, lower than the expected value for the observed color excess of EB-V =0.68 (Forbes et al. 1996) and the average efficiency of polarization for the interstellar dust. The mean angle of the polarization vectors of Hogg 22 is θ=44.9 °, which agrees with the expected angle produce by dust particles aligned in the direction of the Galactic Plane (θ=48°), while for NGC 6204 a lower value, θ=33.7 °, was found. Therefore, we believe that Hogg 22 is depolarized by the same dust that is polarizing NGC 6204, due to different orientations of the dust particles (and magnetic fields) that polarize the starlight. Based on observations obtanined at Complejo Astronómico El Leoncito (CASLEO), operated under agreement between the CONICET and the National Universities of La Plata, Córdoba, and San Juan, Argentina.

  12. 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 of

  13. Kronoseismology: An update on Saturnian waves in the C Ring

    Science.gov (United States)

    Nicholson, Philip D.; French, Richard G.; Hedman, Matthew M.; Cassini VIMS Team, Cassini RSS Team

    2016-10-01

    In previous work (Hedman & Nicholson [2013] Astron. J. 146, 12; Ibid [2014] MNRAS 444, 1369; French et al. [2016] Icarus, in press) we have identified 9 inward-propagating density waves in Saturn's middle C ring with resonances generated by internal oscillations in Saturn. The oscillations involved are sectoral f-modes (ie., fundamental modes with l = m) with m = 1, 2, 3, 4 and 10. In addition, 5 outward-propagating waves in the outer C ring have been identified as density waves driven by 3:2 resonances with fixed gravitational anomalies within the planet (see abstract by El Moutamid et al.)We have now examined several additional C ring waves from the catalog of Baillie et al. [2011], in an attempt to identify weaker and shorter-wavelength waves in the inner C ring. We use a modified version of our previous wavelet-based technique to co-add phase-corrected spectra from multiple occultations, using trial values of `m' and the pattern speed to predict their relative phases. This enables us to detect waves too weak to see in individual occultations. To date, 6 new waves have been identified. Two appear to be due to additional saturnian f-modes, but at unexpected locations. The other 4 waves appear to be a new variety: outward-propagating bending waves driven at vertical resonances with Saturn internal oscillations with l = m + 1. We find bending waves with m = 4, 7, 8 & 9. Only the m = 4 wave is near the location predicted by Marley & Porco [1993].

  14. Kronoseismology III: An update on Saturn-driven waves in the C ring

    Science.gov (United States)

    Nicholson, Philip D.; French, Richard G.; Hedman, Matthew M.

    2016-05-01

    In previous work (Hedman & Nicholson [2013] Astron. J. 146, 12; Ibid [2014] MNRAS 444, 1369; French et al. [2016] Icarus, in press) we have identified 9 inward-propagating density waves in Saturn's C ring with outer Lindblad resonances (OLRs) generated by internal oscillations in Saturn. The oscillations involved are sectoral f-modes (ie., fundamental modes with l = m) with m = 1, 2, 3, 4 and 10. In addition, 5 outward-propagating waves between radii of 84,800 and 86,600 km have been identified as density waves driven by 3:2 tesseral resonances with fixed gravitational anomalies within the planet. (See Hedman et al., this conference.)We have now examined additional C ring waves from the catalog of Baillie et al. [2011], in an attempt to identify several weaker and shorter-wavelength waves in the inner C ring. We use a modified version of our previous wavelet-based technique to coadd phase-corrected spectra from multiple occultations, using trial values of `m` and the pattern speed to predict their relative phases. This enables us to detect waves too weak to see in individual occultations. To date, 6 new waves have been identified. Two appear to be due to additional saturnian f-modes, with m = 2 and m = 9. The other 4 waves appear to be a new variety: outward-propagating bending waves driven at outer vertical resonances (OVRs) with Saturn internal oscillations with l = m + 1. We find waves with m = 4, 7, 8 & 9. All of the newly-identified waves are at radii less than 77,000 km and only the m = 4 OVR is near the location predicted by Marley & Porco [1993].

  15. 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

  16. 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

  17. 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

  18. 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

  19. 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.

  20. 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)

  1. 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.

  2. A Polarimetric Survey for Dust in 47 Tucanae

    Science.gov (United States)

    Forte, Juan C.; Bassino, Lilia P.; Vega, E. Irene; Pellizza González, Leonardo J.; Cellone, Sergio A.; Méndez, Mariano R.

    2002-06-01

    We present linear polarization measurements in the V band for 77 stars in the field of the globular cluster 47 Tucanae (NGC 104) and for 14 regions free of bright stars, located along an elliptical isophotal contour of the cluster, as well as UBVRI measurements for the cluster nucleus. The observations show variable foreground polarization that, once removed, leaves marginally significant polarization residuals for the nonvariable bright red giants. Although these residuals are small, there is a systematic trend in the sense that the larger ones are seen toward the south of the cluster (in a direction opposite to that of the cluster proper motion). In contrast, most of the variable stars do show significant intrinsic polarization. The behavior of the star-free regions is similar to that of the nonvariable stars and sets an upper limit to the possible existence of a global pattern of scattered (and polarized) intracluster light in the V band. In turn, the multicolor observations of the cluster nucleus cannot be fitted with a Serkowski law and exhibit a polarization excess in both U and B. This polarization could be explained as a combination of the foreground interstellar component and another component arising from dust located in the nucleus and illuminated by a bright blue post-asymptotic giant branch star (at 48" from the cluster center). Inspection of a set of archival Hubble Space Telescope Wide Field Planetary Camera 2 images reveals the presence of a number of dark patches in the innermost regions of the cluster. A prominent patch (some 5"×3" in size) located 12" from the cluster center and with a position angle (north to east) of 120° has a slightly different polarization compared with that of the cluster nucleus and appears to be a good candidate for identification as a dust globule within the cluster. Based on observations made at the Complejo Astronómico El Leoncito, which is operated under agreement between CONICET and the National Universities of La

  3. Membership, binarity and metallicity of red giants in the southern open cluster NGC 2354

    Science.gov (United States)

    Clariá, J. J.; Mermilliod, J.-C.; Piatti, A. E.

    1999-01-01

    We present new Coravel radial-velocity observations and photoelectric photometry in the UBV, DDO and Washington systems for a sample of red giant candidates in the field of the intermediate-age open cluster NGC 2354. Photometric membership probabilities show very good agreement with those obtained from Coravel radial velocities. The analysis of the photometric and kinematical data allow us to confirm cluster membership for 9 red giants, one of them being a spectroscopic binary, while 4 confirmed spectroscopic binaries appear to be probable members. We have also discovered 4 spectroscopic binaries not belonging to the cluster. A mean radial velocity of (33.40 +/- 0.27) km s(-1) and a mean reddening E(B-V) = 0.13 +/- 0.03 were derived for the cluster giants. NGC 2354 has a mean ultraviolet excess B)> = -0.03 +/- 0.01, relative to the field K giants, and a mean new cyanogen anomaly Delta CN = -0.035 +/- 0.007, both implying [Fe/H] ~ -0.3. The moderately metal-poor character of NGC 2354 is confirmed using five different metal abundance indicators of the Washington system. The cluster giant branch is formed by a well defined clump of 7 stars and 4 stars with high membership probabilities seem to define an ascending giant branch. The whole red giant locus cannot be reproduced by any theoretical track. Based on observations collected with the Danish\\protect\\linebreak 1.54-m telescope at the European Southern Observatory, La Silla (Chile); at Complejo Astronómico El Leoncito, which is 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, Argentina, and at Cerro Tololo Inter-American Observatory, National Optical Astronomy Observatories, operated by the Association of Universities for Research in Astronomy, Inc., under contract with the National Science Foundation.

  4. Southern Sky Redshift Survey: Clustering of Local Galaxies

    Science.gov (United States)

    Willmer, Christopher N. A.; da Costa, Luiz Nicolaci; Pellegrini, Paulo S.

    1998-03-01

    We use the two-point correlation function to calculate the clustering properties of the recently completed SSRS2 survey, which probes two well-separated regions of the sky, allowing one to evaluate the sensitivity of sample-to-sample variations. Taking advantage of the large number of galaxies in the combined sample, we also investigate the dependence of clustering on the internal properties of galaxies. The redshift-space correlation function for the combined magnitude-limited sample of the SSRS2 is given by xi(s) = [s/(5.85 h^-1 Mpc)]^-1.60 for separations in the range 2 h^-1 Mpc b b is the linear biasing factor for optical galaxies. We have used the SSRS2 sample to study the dependence of xi on the internal properties of galaxies, such as luminosity, morphology, and color. We confirm earlier results that luminous galaxies (L > L^*) are more clustered than sub-L^* galaxies and that the luminosity segregation is scale-independent. We also find that early types are more clustered than late types. However, in the absence of rich clusters, the relative bias between early and late types in real space, b_E+S0/b_S ~ 1.2, is not as strong as previously estimated. Furthermore, both morphologies present a luminosity-dependent bias, with the early types showing a slightly stronger dependence on luminosity. We also find that red galaxies are significantly more clustered than blue ones, with a mean relative bias of b_R/b_B ~ 1.4, stronger than that observed for morphology. Finally, by comparing our results with the measurements obtained from the infrared-selected galaxies, we determine that the relative bias between optical and IRAS galaxies in real space is b_o/b_I ~ 1.4. Based on observations obtained at Cerro Tololo Inter-American Observatory, National Optical Astronomy Observatories, operated by the Association of Universities for Research in Astronomy, Inc., under cooperative agreement with the National Science Foundation; Complejo Astronómico El Leoncito, operated

  5. HD 65949: Rosetta stone or red herring

    Science.gov (United States)

    Cowley, C. R.; Hubrig, S.; Palmeri, P.; Quinet, P.; Biémont, É.; Wahlgren, G. M.; Schütz, O.; González, J. F.

    2010-06-01

    European Southern Observatory, Paranal and La Silla, Chile [ESO programmes 076.D-0172(A) and 081.D-0498(A)], HARPS data obtained during engineering nights and at the Complejo Astronómico El Leoncito. E-mail: cowley@umich.edu

  6. 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

  7. 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 < P < 0,521534 dias y -150×10-10 < β < +150×10-10 dias/dia. El mejor período instantáneo (correspondiente a la época DJ=2.426.908) y su variación secular son P = 0,5212859±0,0000001 días y β 14,012±,010×10-10 días/día respectivamente. Con estos 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 .

  8. PREDICTION OF THE IMPACTS CAUSED BY LIGHT POLLUTION WITH EMPHASIS IN OBSERVATIONAL ASTRONOMY SITES AND SYNTHESIS OF THE NATIONAL LEGISLATION PROPOSAL = PREVISÃO DOS IMPACTOS CAUSADOS POR POLUIÇÃO LUMINOSA COM ÊNFASE NOS SÍTIOS DE OBSERVAÇÃO ASTRONÔMICA E SÍNTESE DA PROPOSTA DE LEGISLAÇÃO NACIONAL

    Directory of Open Access Journals (Sweden)

    Saulo Roberly Gargaglioni

    2012-01-01

    Full Text Available It present the results of (i a literature review on the subject, and also the currently existing legislation in Brazil and other countries that regulate the use of artificial lighting, and in a pioneer way, (ii a preliminary proposal of the Brazilian legislation for the disciplining and the predicting of the impacts caused on observational astronomy sites. It can be concluded that besides the environmental social and economical impact, it will also be extended to the Brazilian astrophysics science where you can see a synthesis of the proposal for the establishment of the legal apparatus. It can be also pointed out the urgency of including specific topics on the regulation of the ISO (International Organization for Standardization, the ABNT (Associação Brasileira de Normas Técnicas, the INMETRO (Instituto Nacional de Metrologia, Qualidade e Tecnologia and also in the development and integration of the criteria for the use of artificial lighting in urban planning through directors plans. = São apresentados os resultados de (i uma revisão bibliográfica sobre o tema, e a legislação existente no Brasil e de outros países que regulamentam o uso da iluminação artificial e, de maneira pioneira, (ii uma proposta preliminar da legislação brasileira de disciplinamento e previsão dos impactos provocados em sítios de observação astronômica. Conclui-se que, além dos impactos ambientais, sociais e econômicos, a ciência astrofísica brasileira também sofrerá perdas significativas causadas pela poluição luminosa, mas, diante disso, é demonstrada uma síntese da proposta para criação de aparato legal. Destaca-se, também, a urgência da inclusão de tópicos específicos sobre a regulamentação nas normas ISO (International Organization for Standardization, na ABNT (Associação Brasileira de Normas Técnicas, no INMETRO (Instituto Nacional de Metrologia, Qualidade e Tecnologia e na criação e na inserção de critérios de uso da

  9. Search for a Variation of Fundamental Constants

    Science.gov (United States)

    Ubachs, W.

    2013-06-01

    Since the days of Dirac scientists have speculated about the possibility that the laws of nature, and the fundamental constants appearing in those laws, are not rock-solid and eternal but may be subject to change in time or space. Such a scenario of evolving constants might provide an answer to the deepest puzzle of contemporary science, namely why the conditions in our local Universe allow for extreme complexity: the fine-tuning problem. In the past decade it has been established that spectral lines of atoms and molecules, which can currently be measured at ever-higher accuracies, form an ideal test ground for probing drifting constants. This has brought this subject from the realm of metaphysics to that of experimental science. In particular the spectra of molecules are sensitive for probing a variation of the proton-electron mass ratio μ, either on a cosmological time scale, or on a laboratory time scale. A comparison can be made between spectra of molecular hydrogen observed in the laboratory and at a high redshift (z=2-3), using the Very Large Telescope (Paranal, Chile) and the Keck telescope (Hawaii). This puts a constraint on a varying mass ratio Δμ/μ at the 10^{-5} level. The optical work can also be extended to include CO molecules. Further a novel direction will be discussed: it was discovered that molecules exhibiting hindered internal rotation have spectral lines in the radio-spectrum that are extremely sensitive to a varying proton-electron mass ratio. Such lines in the spectrum of methanol were recently observed with the radio-telescope in Effelsberg (Germany). F. van Weerdenburg, M.T. Murphy, A.L. Malec, L. Kaper, W. Ubachs, Phys. Rev. Lett. 106, 180802 (2011). A. Malec, R. Buning, M.T. Murphy, N. Milutinovic, S.L. Ellison, J.X. Prochaska, L. Kaper, J. Tumlinson, R.F. Carswell, W. Ubachs, Mon. Not. Roy. Astron. Soc. 403, 1541 (2010). E.J. Salumbides, M.L. Niu, J. Bagdonaite, N. de Oliveira, D. Joyeux, L. Nahon, W. Ubachs, Phys. Rev. A 86, 022510

  10. Coordination of NEO Observers in South-America

    Science.gov (United States)

    Tancredi, G.

    At present the discovery of NEOs is concentrated in the Northern Hemisphere. None of the 6 existing survey programs can reach declinations below -30deg. Nevertheless, there are two small surveys ready to start in the near future in the southern hemisphere: an extension of the Catalina Sky Survey using the Uppsala Schmidt in Siding Spring and the Project BUSCA in Uruguay. Many of the NEOs discovered by the northern surveys could reach the southern sky, with declinations unreachable for a northern observer. Furthermore, the recovery of an asteroid in subsequent oppositions could come indistinctly in the northern and southern sky. A network of well-equipped observers in the southern region is then a must in a campaign to catalog the NEO population. In view of this situation, the Planetary Society, through its NEO grant, have already supported many observers in the Southern Hemisphere. The planetary science community in South America has considerably grown in the last 10 years. We have well-known research groups in Argentina, Brazil and Uruguay. Those groups have established many scientific links by exchanging graduate students and through several meetings. In particular, we have already hold two Workshop in Planetary Science in South America in 1999 (La Plata, Argentina) and 2000 (Montevideo, Uruguay) with more than 25 participants each. Recently, in February 2002, we organized a Workshop of NEO observers in Montevideo with the participation of more than 20 professional and amateurs observers from: Argentina: Obs. Ast. Felix Aguilar - Yale University (San Juan) and CRICYT (Mendoza); Brazil: Obs. Abraes de Moraes (San Pablo), Obs. Wykrota (Belo Horizonte) and Observatorio Nacional (Rio de Janeiro); Paraguay: Obs. Nacional de Asuncion and Sociedad de Estudios Astronómicos (Asunción) Uruguay: Depto. Astronomía - Fac. Ciencias, Obs. Ast. Los Molinos and Obs. Kappa Crucis (Montevideo). Among the resolutions of the Workshop, we highlight: * Creation of the "Asociaci

  11. Time Series Analysis of SOLSTICE Measurements

    Science.gov (United States)

    Wen, G.; Cahalan, R. F.

    2003-12-01

    -499, 1999. Fröhlich, C. and J. Lean, IAU Symposium 185: New Eyes to See Inside the Sun and Stars, edited by F. L. Deubner, 82-102, Kluwer Academic Publ., Dordrecht, The Netherland, 1998. Haykin, S., 696 pp, Macmillan, New York, 1994. Kennel, M. B. and H. D. I. Abarbanel, Phys. Rev. E 66, 026209, 2002. Krivova, N. A., S. K. Solanki, M. Fligge, and Y. C. Unruh, 399, L1-L4, 2003. Lean, J., Annu. Rev. Astron. Astrophys., 35, 33-67, 1997.

  12. The BlackGEM array in search of black hole mergers: integrated performance modelling

    Science.gov (United States)

    Roelfsema, Ronald; Klein Wolt, Marc; Bloemen, Steven; Groot, Paul; Bettonvil, Felix; Balster, Harry; Dolron, Peter; van Elteren, Arjen; Engels, Arno; de Haan, Menno; ter Horst, Rik; Kragt, Jan; Navarro, Ramon; Nelemans, Gijs; Paalberends, Willem Jelle; Pal, Sari; Raskin, Gert; Rutten, Harrie; Scheers, Bart; Schuil, Menno; Sybilski, Piotr

    2016-07-01

    The Radboud University Nijmegen in collaboration with the NOVA Optical Infrared Instrumentation group at ASTRON is currently leading the development and realization of the BlackGEM observing facility. The BlackGEM science team aims to be the first to catch the optical counterpart of a gravitational wave event. The BlackGEM project will put an array of three medium-sized optical telescopes at the La Silla site of the European Southern Observatory in Chile. It is uniquely equipped to achieve a combination of wide-field and high sensitivity through its array-like approach. Each BlackGEM unit telescope is a modified Dall-Kirkham-type telescope consisting of a 65cm primary mirror, a 21cm spherical secondary mirror and a triplet corrector lens. The spatial resolution on the sky will be 0.56 asec/pixel and the total field-of-view per telescope is 2.7 square degrees. The main requirement is to achieve a 5-sigma sensitivity of 23rd magnitude within a 5-minute exposure under 15 m/s wind gust conditions. This demands a very stable optical system with tight control of all the error contributions. This has been realized with a spreadsheet based integrated instrument model. The model contains all relevant telescope instrument parameters and environmental conditions. The spreadsheet is partly used for performance calculations and partly used to combine and integrate the output from several other sources. The spreadsheet model calculates the overall performance based on an Exposure Time Calculator using the Noise Equivalent Area metric (NEA). The NEA is further budgeted over 7 main High Level Requirements. The spreadsheet model is coupled to 1) a ZEMAX telescope optical model 2) a telescope FEM analysis to predict the optomechanical response under various gravity, temperature and wind load conditions, 3) a Matlab Simulink thermal model to predict the transient temperature behaviour of the most important telescope elements and 4) a Matlab Simulink control model to predict the

  13. 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.

  14. 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).

  15. 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

  16. 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.

  17. Binaries discovered by the SPY survey. VI. Discovery of a low mass companion to the hot subluminous planetary nebula central star EGB 5 - a recently ejected common envelope?

    Science.gov (United States)

    Geier, S.; Napiwotzki, R.; Heber, U.; Nelemans, G.

    2011-04-01

    Hot subdwarf B stars (sdBs) in close binary systems are assumed to be formed via common envelope ejection. According to theoretical models, the amount of energy and angular momentum deposited in the common envelope scales with the mass of the companion. That low mass companions near or below the core hydrogen-burning limit are able to trigger the ejection of this envelope is well known. The currently known systems have very short periods ≃0.1-0.3 d. Here we report the discovery of a low mass companion (M2 > 0.14 M⊙) orbiting the sdB star and central star of a planetary nebula EGB 5 with an orbital period of 16.5 d at a minimum separation of 23 R⊙. Its long period is only just consistent with the energy balance prescription of the common envelope. The marked difference between the short and long period systems will provide strong constraints on the common envelope phase, in particular if the masses of the sdB stars can be measured accurately. Due to selection effects, the fraction of sdBs with low mass companions and similar or longer periods may be quite high. Low mass stellar and substellar companions may therefore play a significant role for the still unclear formation of hot subdwarf stars. Furthermore, the nebula around EGB 5 may be the remnant of the ejected common envelope making this binary a unique system to study this short und poorly understood phase of binary evolution. Based on observations at the Paranal Observatory of the European Southern Observatory for programmes No. 167.H-0407(A) and 71.D-0383(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). Some of the data used in this work were obtained at the William Herschel Telescope (WHT) operated by the Isaac Newton Group of Telescopes (ING).

  18. 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.

  19. 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.

  20. Questões mais freqüentes na área de astronomia

    Science.gov (United States)

    Segundo, H. A. S.; Garcia, G. C.; Caretta, C. A.; Lima, F. P.

    2003-08-01

    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 otimizar a divulgação e o ensino não formal de Astronomia aliando a adequação do conteúdo à expectativa das pessoas. Nesse intuito, nosso trabalho busca mapear que assuntos da Astronomia despertam mais a atenção e o interesse das pessoas e o quanto disso é estimulado pela mídia, que freqüentemente aproveita-se desse interesse de forma sensacionalista, trazendo contribuições positivas e negativas. Para esta avaliação, utilizamos as pesquisas específicas e de caracterização do público que freqüentou o MAst nos anos de 2001 a 2003, pesquisa das matérias de Astronomia veiculadas na mídia escrita da cidade do Rio de Janeiro no mesmo período, além da base de dados do programa Pergunte a um astrônomo, realizado no Observatório Nacional nos anos de 1997 a 1999. Para a análise dos dados, dividimos as perguntas em dez categorias, cada uma com suas subcategorias, tomando como referência as divisões, comissões e grupos de trabalho da IAU. Apresentamos neste trabalho os resultados dessa pesquisa, que incluem, entre outros, a predominância de questões nas categorias Observação do Céu e Sistemas Planetários enquanto nos jornais dominam as notícias de Sistemas Planetários e Espaço & Astronáutica. Outro resultado interessante indicou que as dúvidas de crianças do ensino fundamental se concentram em algumas categorias enquanto as questões de adultos são mais distribuídas por todas as categorias. Os resultados dessa pesquisa serão aplicados diretamente no aperfeiçoamento das atividades do Programa de Observação de Céu, bem como na elaboração de novos projetos e eventos realizados no MAst.