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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. 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.

  3. Modelos de Refracción Astronómica

    OpenAIRE

    Prieto Morin, Juan Francisco; Velasco Gomez, Jesus

    2011-01-01

    Se resumen en esta monografía la teoría básica sobre refracción astronómica para ser aplicada a observaciones topográficas a astros. Se comentan también los diferentes modelos matemáticos existentes hasta la fecha.

  4. Alfabetización astronómica

    Science.gov (United States)

    Tignanelli, H.

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

  5. RadioAstron gravitational redshift experiment: status update

    CERN Document Server

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

    2016-01-01

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

  6. The RadioAstron Green Bank Earth Station

    Science.gov (United States)

    Ford, H. Alyson; Anderson, Robert; Belousov, Konstantin; Brandt, Joseph J.; Ford, John M.; Kanevsky, Boris; Kovalenko, Anatoly; Kovalev, Yuri Y.; Maddalena, Ronald J.; Sergeev, Sergei; Smirnov, Alexander; Watts, Galen; Weadon, Timothy Lee

    2014-07-01

    We present the design, commissioning, and initial results of the Green Bank Earth Station (GBES), a RadioAstron data downlink station located at the National Radio Astronomy Observatory (NRAO) in Green Bank, West Virginia. The GBES uses the modernized and refurbished NRAO 140ft telescope. Antenna optics were refurbished with new motors and drives fitted to the secondary mirror positioning system, and the deformable subreflector was refurbished with a new digital controller and new actuators. A new monitor and control system was developed for the 140ft and is based on that of the Green Bank Telescope (GBT), allowing satellite tracking via a simple scheduling block. Tools were developed to automate antenna pointing during tracking. Data from the antenna control systems and logs are retained and delivered with the science and telemetry data for processing at the Astro Space Center (ASC) of the Lebedev Physical Institute (LPI) of the Russian Academy of Sciences and the mission control centre, Lavochkin Association.

  7. 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.

  8. 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.

  9. Observatorio Astronómico Nacional. Ciencia y Memoria para la Sociedad

    OpenAIRE

    Badawi, Halim; Roa Triana, Julian; Torres Carreño, Guillermo Andrés; Cortés, Diego; Castell, Edmon

    2008-01-01

    Observatorio Astronómico Nacional hace parte del Sistema de Patrimonio Cultural y Museos SPM. Esta infografía contiene una cronología del Observatorio, eventos importantes de la historia de Colombia que se desarrollaron en este espacio y describe el proyecto de Sistema de Museos.

  10. Historia de la Ciencia árabe: los sitemas astronómicos

    OpenAIRE

    Torroja, J. M.

    1981-01-01

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

  11. Gravitational Redshift Experiment with the Space Radio Telescope RadioAstron

    CERN Document Server

    Litvinov, D; Belousov, K; Bietenholz, M; Biriukov, A; Fionov, A; Gusev, A; Kauts, V; Kovalenko, A; Kulagin, V; Poraiko, N; Rudenko, V

    2015-01-01

    A unique test of general relativity is possible with the space radio telescope RadioAstron. The ultra-stable on-board hydrogen maser frequency standard and the highly eccentric orbit make RadioAstron an ideal instrument for probing the gravitational redshift effect. Large gravitational potential variation, occurring on the time scale of $\\sim$24 hr, causes large variation of the on-board H-maser clock rate, which can be detected via comparison with frequency standards installed at various ground radio astronomical observatories. The experiment requires specific on-board hardware operating modes and support from ground radio telescopes capable of tracking the spacecraft continuously and equipped with 8.4 or 15 GHz receivers. Our preliminary estimates show that $\\sim$30 hr of the space radio telescope's observational time are required to reach $\\sim 2\\times10^{-5}$ accuracy in the test, which would constitute a factor of 10 improvement over the currently achieved best result.

  12. 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.

  13. 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.

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

    Science.gov (United States)

    Johnson, Michael D.; Kovalev, Yuri Y.; 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.

    2016-03-01

    Earth-space interferometry with RadioAstron provides the highest direct angular resolution ever achieved in astronomy at any wavelength. RadioAstron detections of the classic quasar 3C 273 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 likely 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 6.2 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 1.35 {{cm}}, the substructure does not affect the extremely high inferred brightness temperatures, in excess of {10}13 {{K}}. We also demonstrate that for a source having a Gaussian surface brightness profile, a single long-baseline estimate of refractive substructure determines an absolute minimum brightness temperature, if the scattering properties along a given line of sight are known, and that this minimum accurately approximates the apparent brightness temperature over a wide range of total flux densities.

  15. 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....

  16. 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

  17. 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.

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

    International Nuclear Information System (INIS)

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

  19. Theoretical Study of E-Layer and Plasma Behaviour in Astron

    International Nuclear Information System (INIS)

    The injection, equilibrium, and stability of the E-layer and confined plasma in Astron ate Investigated. Self-consistent equilibrium configurations for a collisionless E -layer and an ideal plasma fluid have been obtained from a numerical solution of Ampere's law, using various models for both the E-layer and the plasma pressure profiles. The degree of field reversal and the shape of the magnetic well can be varied so as to obtain equilibria with favourable stability properties. The stability of an E-layer, alone or in conjunction with a cold background plasma, has been analysed for modes with wavelengths less than or comparable to E-layer dimensions. The results are in good qualitative agreement with experimental observations on the precession, negative-mass, and plasma hybrid modes. The most important stabilizing mechanism is seen to be energy spread in the E-layer. The stability of the confined plasma is investigated using the magnetohydiodynamic (MHD) energy principle. A numerical solution of the eigenvalue problem, which arises from minimization of the potential energy, allows the MHD-stability of any of the equilibrium models used to be tested. The limiting plasma pressure is determined, and specific numerical examples of stable equilibria are given. A time -dependent numerical model of the Astron, with which injection and trapping can be studied in detail, has also been developed. The effects due to the resistors, neutralization, and the ambient plasma have been included. The model is axially symmetric. The E-layer electrons are simulated by many thousands of finite-size super-particles, which move in the r-z domain and have velocity components vr, vθ , and vz. The model is relativistic and the electromagnetic fields are obtained by solving four wave equations — three for the vector potential and one for the scalar potential. The E-layer and plasma currents and the current induced in the resistor wires are included in the above field equations. The

  20. 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

  1. The Nuclear Structures of Cen A, M87 and 3C273 at Very High Resolution with RadioAstron and the LBA

    Science.gov (United States)

    Reynolds, Cormac; Lobanov, Andrei; Giovannini, Gabriele; Orienti, Monica; Tingay, Steven; Kovalev, Yuri; Krichbaum, Thomas P.; Savolainen, Tuomas; Anderson, James M.

    2013-10-01

    We request 30 hours of LBA time to perform perigee imaging observations with the RadioAstron orbiting VLBI antenna. RadioAstron provides a unique opportunity to image nearby AGN at unprecedented resolution and will allow us to address fundamental questions related to the jet formation process in AGN. The proposed observations can reveal the nuclear structures in these objects down to scales of just a few Schwarzschild radii, a resolution that will allow us to compare observational data on the region where the jets are launched and collimated to the predictions of analytical models and simulations.

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

    Science.gov (United States)

    Kovalev, Y. Y.; Kardashev, N. S.; 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.

    2016-03-01

    Inverse Compton cooling limits the brightness temperature of the radiating plasma to a maximum of 1011.5 K. Relativistic boosting can increase its observed value, but apparent brightness temperatures much in excess of 1013 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 1013 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.

  3. The abundance of ammonia in Comet P/Halley derived from ultraviolet spectrophotometry of NH by ASTRON and IUE

    Science.gov (United States)

    Feldman, P. D.; Fournier, K. B.; Grinin, V. P.; Zvereva, A. M.

    1993-01-01

    From an analysis of the spatial profiles of both the NH and OH UV emissions observed by the ASTRON satellite, the ratio of ammonia-to-water production rates in Comet Halley on April 9, 1986 is derived and found to lie in the range of 0.44-0.94 percent. In order to compare this result with those based on both ground-based and in situ observations made on other dates during the 1985-1986 apparition of the comet, the IUE observational data base for December 1985 and March-April 1986 is used to evaluate the ratio of NH to OH column density in the IUE field of view and thus constrain the long-term behavior of this ratio. The IUE data base indicates that, to within a factor of 2, the ammonia-to-water production rate ratio is the same for a small sample of moderately bright comets observed recently.

  4. 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.

  5. 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...

  6. 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.

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

    OpenAIRE

    Alonso Lifante, María Pilar

    2014-01-01

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

  8. Control remoto del sistema B+G del Observatorio Astronómico del Montsec: monitorización de funciones.

    OpenAIRE

    Clavero Quílez, Javier

    2006-01-01

    En el año 2001 la Generalitat de Cataluña creó el Consorcio del Montsec para la ejecución del proyecto Montsec Sostenible. En el marco de este proyecto y mediante la colaboración de diversos departamentos de las Universidades públicas de Cataluña, entre las cuales se encuentran los departamentos de Física Aplicada (FA) y de Física e Ingeniería Nuclear (FEN), de la Universidad Politécnica de Cataluña (UPC), se creó el Parque Astronómico del Montsec (PAM). El Observatorio Astronómico del Mo...

  9. 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...

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

    Science.gov (United States)

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

    2014-12-01

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

  11. 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...

  12. Probing the Innermost Regions of AGN Jets and Their Magnetic Fields with RadioAstron. I. Imaging BL Lacertae at 21 Microarcsecond Resolution

    Science.gov (United States)

    Gómez, José L.; Lobanov, Andrei P.; 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.

    2016-02-01

    We present the first polarimetric space very long baseline interferometry (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 less than 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 diameters in length, allowing us to image the jet in BL Lacertae with a maximum angular resolution of 21 μas, 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 μas from the jet apex, in a pattern that includes other recollimation shocks at approximately 100 and 250 μas 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 analysis, obtained from combining RadioAstron 22 GHz and ground-based 15 and 43 GHz images, shows a gradient in rotation measure and Faraday-corrected polarization vector as a function of position angle with respect to the core, suggesting that the jet in BL Lacertae is threaded by a helical magnetic field. The intrinsic de-boosted brightness temperature in the unresolved core exceeds 3× {10}12 K, suggesting, at the very least, departure from equipartition of energy between the magnetic field and radiating particles.

  13. OH maser observations using the Russian interferometric network ``Quasar'' in preparation for scientific observations with the space mission RadioAstron.

    Science.gov (United States)

    Litovchenko, I. D.; Alakoz, A. V.; Kostenko, V. I.; Lihachev, S. F.; Finkelstein, A. M.; Ipatov, A. V.

    2012-07-01

    We present results of a VLBI experiment at a wavelength of 18 cm, which simulates the ground-space interferometer with space link to RadioAstron. An array of five antennas was used, four of them are located in the Russian Federation, plus the the 32-m radio telescope in Medicine (Italy). The 22-m radio telescope in Pushchino (Moscow Region) acted in place of the space arm. It has an effective area of 100 square meters. The three other Russian 32-m antennas are operated by the Institute of Applied Astronomy RAS; they are located at Badary, Svetloe and Zelenchukskaya (interferometer network ``Quasar''). The maximum base-line, Badary-Svetloe, was about 4402 km, providing an angular resolution of about 0.009 arc seconds at a wavelength of 18 cm. The duration of the experiment was 10 hours on 02/03 February 2011. The program of observations included quasars 3C273, 3C279, 3C286 and the maser source - W3(OH). W3(OH) was observed only by the Russian telescopes and was investigated at the frequency of the 1665 MHz main line. The data were recorded on the MK5 recorder (32-m radio telescopes) and the RDR system (RadioAstron Digital Recorder) in Pushchino. The low SEFD (system equivalence of flux density) of Pushchino emulated the RadioAstron antenna. Correlation was performed with the universal software correlator of the AstroSpace Center of Lebedev Physical Institute. The correlator output format is compatible with that used by the AIPS package, which was used for data analysis. After analyzing the correlated data we obtained relative coordinates of the maser components. The main results are tabulated and presented in the figures. The data quality is sufficient for astrophysical analysis and comparison with previous observations of maser source W3(OH) on VLBI networks EVN and VLBA.

  14. Análise dos Conceitos Astronômicos Apresentados por Professores de Algumas Escolas Estaduais Brasileiras

    Science.gov (United States)

    Voelzke, Marcos Rincon; Gonzaga, Edson Pereira

    2011-12-01

    A razão para o desenvolvimento deste trabalho baseia-se no fato de que muitos professores da Educação Básica (EB) não lidam com conceitos relacionados à astronomia, e quando o fazem eles simplesmente seguem livros didáticos que podem conter erros conceituais. Como é de conhecimento geral a astronomia é um dos conteúdos a serem ensinados na EB fazendo parte dos Parâmetros Curriculares Nacionais e das Propostas Curriculares do Estado de São Paulo, mas é um fato, que vários pesquisadores apontam, a existência de muitos problemas no ensino da astronomia. Com o propósito de minimizar algumas dessas deficiências foi realizado um trabalho de pesquisa com a utilização de questionários pré e pós pesquisa, para tanto foi desenvolvido um Curso de Extensão Universitária para professores da Diretoria de Ensino Regional (DE) que abrange Mauá, Ribeirão Pires e Rio Grande da Serra (no Estado de São Paulo) com os seguintes objetivos: levantar concepções alternativas; subsidiar os professores por meio de palestras, debates e workshops, e verificar o sucesso da aprendizagem após o curso, adotando-se como referência, para a análise dos resultados, os dicionários de Língua Portuguesa (FERREIRA, 2004) e Enciclopédico de Astronomia e Astronáutica (MOURĀO, 1995). Portanto, dezesseis questões foram aplicadas antes e após o curso, assim pode-se verificar após a pesquisa que 100,0% dos professores sabiam os nomes das fases da Lua, 97,0% entenderam que o Sistema Solar é composto por oito planetas, 78,1% foram capazes de explicar como ocorre um eclipse lunar, um eclipse solar e um solstício, 72,7% sabiam como explicar a ocorrência das estações do ano; 64,5% explicaram corretamente a ocorrência do equinócio, 89,7% foram capazes de definir adequadamente o termo cometa; 63,6% definiram asteróide, 54,5% meteoro, 58,1% galáxia, e 42,4% planeta. Os resultados obtidos indicam uma aprendizagem significativa por parte dos participantes.

  15. 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 ...

  16. 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...

  17. 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

  18. 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

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

    OpenAIRE

    Lacroizette i Mañas, Xavier

    2004-01-01

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

  20. 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.

  1. PSR B0329+54: Substructure in the scatter-broadened image discovered with RadioAstron on baselines of up to 235,000 km

    CERN Document Server

    Popov, M V; Bartel, N; Gwinn, C R; Johnson, M D; Joshi, B C; Kardashev, N S; Karuppusamy, R; Kovalev, Y Y; Kramer, M; Rudnitskii, A G; Safutdinov, E R; Shishov, V I; Smirnova, T V; Soglasnov, V A; Zensus, J A; Zhuravlev, V I

    2015-01-01

    We studied scattering properties of the pulsar PSR B0329+54 with a ground-space radio interferometer RadioAstron which included the 10-m Space Radio Telescope, the 110-m Green Bank Telescope, the 14x25-m Westerbork Synthesis Radio Telescope, and the 64-m Kalyazin Radio Telescope. The observations were performed at 324 MHz on baselines of up to 235,000 km in November 2012 and January 2014. At short ground-space baselines of less than about 20,000 km, the visibility amplitude decreases with the projected baseline length, providing a direct measurement of the diameter of the scattering disk of 4.7$\\pm$0.9 mas. The size of the diffraction spot near Earth is 15,000$\\pm$3,000 km. At longer baselines of up to 235,000 km, where no interferometric detection of the scattering disk would be expected, significant visibilities were observed with amplitudes scattered around a constant value. These detections result in a discovery of a substructure in the completely resolved scatter-broadened image of the pointlike source, ...

  2. 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. ...

  3. PSR B0329+54: Statistics of Substructure Discovered within the Scattering Disk on RadioAstron Baselines of up to 235,000 km

    Science.gov (United States)

    Gwinn, C. R.; Popov, M. V.; Bartel, N.; Andrianov, A. S.; Johnson, M. D.; Joshi, B. C.; Kardashev, N. S.; Karuppusamy, R.; Kovalev, Y. Y.; Kramer, M.; Rudnitskii, A. G.; Safutdinov, E. R.; Shishov, V. I.; Smirnova, T. V.; Soglasnov, V. A.; Steinmassl, S. F.; Zensus, J. A.; Zhuravlev, V. I.

    2016-05-01

    We discovered fine-scale structure within the scattering disk of PSR B0329+54 in observations with the RadioAstron ground–space radio interferometer. Here we describe this phenomenon, characterize it with averages and correlation functions, and interpret it as the result of decorrelation of the impulse-response function of interstellar scattering between the widely separated antennas. This instrument included the 10 m Space Radio Telescope, the 110 m Green Bank Telescope, the 14 × 25 m Westerbork Synthesis Radio Telescope, and the 64 m Kalyazin Radio Telescope. The observations were performed at 324 MHz on baselines of up to 235,000 km in 2012 November and 2014 January. In the delay domain, on long baselines the interferometric visibility consists of many discrete spikes within a limited range of delays. On short baselines it consists of a sharp spike surrounded by lower spikes. The average envelope of correlations of the visibility function shows two exponential scales, with characteristic delays of {τ }1=4.1+/- 0.3 μ {{s}} and {τ }2=23+/- 3 μ {{s}}, indicating the presence of two scales of scattering in the interstellar medium. These two scales are present in the pulse-broadening function. The longer scale contains 0.38 times the scattered power of the shorter one. We suggest that the longer tail arises from highly scattered paths, possibly from anisotropic scattering or from substructure at large angles.

  4. 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...

  5. 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

  6. 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.

  7. 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

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

    OpenAIRE

    María Álvarez Lires; Irene Pérez Rodríguez; Uxío Pérez Rodríguez

    2009-01-01

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

  9. 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.

  10. 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

  11. 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

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

    Directory of Open Access Journals (Sweden)

    María Álvarez Lires

    2009-11-01

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

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

    Science.gov (United States)

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

    2009-03-01

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

  14. 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.

  15. Expresiones de origen náutico en el nacimiento de las distintas formas de volar: aerostación, aviación y astronáutica Expressions of marine origin in the birth of the different ways to fly: aeronautics, aviation and astronautics

    OpenAIRE

    Lorena M. A. de-Matteis

    2012-01-01

    En la comunicación cotidiana se puede observar que el nivel léxico-semántico liga a la aerostación, la aviación y la astronáutica en una relación de continuidad de base analógica. Esta conexión se funda, en primer lugar, por procesos de trasvase terminológico de las respectivas técnicas y, luego, en la adopción social de las unidades léxicas de origen técnico, por el empleo de metáforas para explicar la nueva realidad. De esta manera, el análisis léxico muestra que aerostación, aviación y exp...

  16. 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.

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

    Science.gov (United States)

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

    2014-01-01

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

  18. 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.

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

    Science.gov (United States)

    Janot-Pacheco, E.

    2012-12-01

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

  20. La curiosa historia de… Un sencillo problema astronómico

    OpenAIRE

    Martinez, Mariano

    1990-01-01

    En el grupo de ciencia recreativa constatamos cómo un buen número de experiencias tienen un carácter ambivalente y sólo un cierto “enfoque” llevará a considerar la experiencia del campo de las matemáticas, la física o la biología.

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

    Science.gov (United States)

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

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

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

    OpenAIRE

    Bustos, Ricardo; Rubio, Mónica; 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, 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 (56...

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

    OpenAIRE

    Di Sisto, Romina Paula

    1999-01-01

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

  4. 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.

  5. 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

  6. Conservación de material histórico sobre papel en el Observatorio Astronómico de la Universidad Nacional de Córdoba

    Science.gov (United States)

    Laguzzi, N.; Tonini, A.; Andreoli, G.; Goldes, G.; Paolantonio, S.; Cequeira, F.; Landi, L.; Alba, J.

    At the recently created Astronomical Museum ``Pte. Sarmiento - Dr. Benjamin Gould", the task of preventive conservation of historic documents has been faced. These materials include: 1) letters exchanged between national authorities and the directors of the Observatory, during the first decades (1870-1880-1890); b) original observation logs from these very first times, containing astrometrical and photometrical data; c) a variety of ancient books and papers; d) administrative documents. The state of conservation of this patrimony was varied: since well-conserved books and letters, to highly degraded logs. The observation logs written by B. Gould and the astronomers who followed him had been stocked in a safe with a permanent humidity of about 70 %, without any ventilation and exposed to the attack of insects of the family ``dermestidae." These conditions could not be worse for the conservation of paper. In order to stop the proccess of degradation and create a healthy environment for written-paper conservation, a team was formed with personnel belonging to the Cultural Area of the Municipality. The tasks being performed on the observation logs are: 1) an initial, mechanical cleaning, performed once the material is extracted from the contaminated safe: by these means, adult insects and pupas are removed 2) a stage of about two weeks of duration, in which the logs are mantained in a vacuum chamber, in orden to completely eliminate the adult, pupa and egg stage insects by anoxia 3) the final mechanical cleaning 4) storage in a clean location. In order to perform these tasks, we work in collaboration with the Environmental Observatory of the City, and the group of Material-Science Research of Fa.M.A.F. Regarding the letters, a mechanical cleaning was performed. After that, the letters were digitized by means of a scanner, inventoried, put inside acid-free polipropylene envelops and filed for conservation, protected from intense light and external sources of contamination. Copies of these letters will be included as exhibits.

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

    OpenAIRE

    García Herrero, José Luis

    2014-01-01

    Astronomy is part of the scientific curriculum in compulsory education. It includes some basic traditional concepts as seasons, lunar phases, the movements of the Earth, eclipses…, but leaves aside some other more contemporary concepts such as exoplanets and cosmology. In the first place, this paper focuses on the level of basic knowledge on astronomy basic concepts by secondary education (ESO) teachers, in order to detect possible training gaps and alternative conceptions. The study included...

  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. Del ángulo de la geometría a los ángulos en el cielo : dificultades para la conceptualización de las coordenadas astronómicas acimut y altura

    OpenAIRE

    Lanciano, Nicoletta; Camino, Néstor

    2008-01-01

    Se presenta en este trabajo una discusión acerca de las dificultades en el proceso de aprendizaje de la definición y medición de los ángulos en el espacio físico (3D) necesarios para la determinación de posiciones sobre la esfera celeste. Se discuten en particular las características de las coordenadas acimut y altura, y los problemas que son propios al proceso de su medición. Se analizan además los datos obtenidos a partir de entrevistas personales, clases grupales y dibujos individuales rea...

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

    Directory of Open Access Journals (Sweden)

    José Luis GARCÍA HERRERO

    2014-11-01

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

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

    OpenAIRE

    José Luis GARCÍA HERRERO

    2014-01-01

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

  12. Pierre-François Tonduti-De-Saint-Légier. A forgotten astronomer. (German Title: Pierre-François Tonduti-De-Saint-Légier. Ein vergessener Astron )

    Science.gov (United States)

    Hein, Olaf; Mader, Rolf

    P.-F. Tonduti (1583-1669) was a recognised scholar of his time and communicated with many outstanding astronomers. He revised Kepler's "Rudolphine Tables" and made two tables for their easier usage. Tonduti carefully observed the annular solar eclipse of April 8, 1633. In 1634 he determined the geographical latitude of Avignon, which method is analysed here in detail. A pedigree of the family and a list of works by Tonduti are given as appendices.

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

    Science.gov (United States)

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

    2007-08-01

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

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

    Science.gov (United States)

    Pogrebinsky, L.; Francile, C.

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

  15. 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.

  16. 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.

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

    OpenAIRE

    García Martín, Rubén

    2009-01-01

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

  18. 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

  19. 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).

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

    OpenAIRE

    Peralta, Romina Alejandra; Canaparo, Juan Francisco

    2013-01-01

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

  1. The LOFAR Pulsar Data Pipeline

    NARCIS (Netherlands)

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

    2009-01-01

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

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

    Science.gov (United States)

    Del Popolo, A.; Pace, F.

    2016-05-01

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

  3. 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

  4. 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.

  5. O cômputo do tempo na civilização indiana

    OpenAIRE

    Thomaz, Luís Filipe F. R.

    2014-01-01

    Os sistemas de cômputo do tempo na Índia são extremamente complexos, devido a dois factores: em primeiro lugar a coexistência não só de diversas teorias e tabelas astronómicas mas também de diferentes calendários, que em parte resulta de a Índia raramente ao longo da sua história ter constituído uma unidade política; em segundo lugar uma grande preocupação, quiçá de origem mágica, com a objectividade astronómica dos dados utilizados no cômputo do tempo. Do primeiro factor indicado resultam, p...

  6. A New Look at Mode Conversion in a Stratified Isothermal Atmosphere

    CERN Document Server

    McDougall, A M D

    2007-01-01

    Recent numerical investigations of wave propagation near coronal magnetic null points (McLaughlin and Hood: Astron. Astrophys. 459, 641,2006) have indicated how a fast MHD wave partially converts into a slow MHD wave as the disturbance passes from a low-beta plasma to a high-beta plasma. This is a complex process and a clear understanding of the conversion mechanism requires the detailed investigation of a simpler model. An investigation of mode conversion in a stratified, isothermal atmosphere, with a uniform, vertical magnetic field is carried out, both numerically and analytically. In contrast to previous investigations of upward-propagating waves (Zhugzhda and Dzhalilov: Astron. Astrophys. 112, 16, 1982a; Cally: Astrophys. J. 548, 473, 2001), this paper studies the downward propagation of waves from a low-beta to high-beta environment. A simple expression for the amplitude of the transmitted wave is compared with the numerical solution.

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

    International Nuclear Information System (INIS)

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

  8. 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

  9. 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

  10. 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

  11. The properties of radio ellipticals

    International Nuclear Information System (INIS)

    Optical and additional radio data are presented for the bright galaxies of the Disney and Wall survey (1977 Mon. Not. R. Astron. Soc. 179, 235). These data form the basis of a statistical comparison of the properties of radio elliptical galaxies to radio-quiet ellipticals. The correlations may be explained by the depth of the gravitational potential well in which the galaxy resides governing the circumstances under which an elliptical galaxy rids itself of internally produced gas. (author)

  12. 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).

  13. Geiger avalanche photodiodes as tentative light detectors for VHE gamma ray astronomy

    OpenAIRE

    Pellion, D; Pellion, Denis; Jradi, K; Le Padellec, A.; Rennane, Abdelali; Moutier, F.; Borrel, V.; Estève, Daniel; Magenc, C.; R. Bazer-Bachi, A.

    2009-01-01

    Due to its sensitivity and speed, the detector still widely used in Cerenkov astrophysics experiments remains the PhotoMultiplier Tube (PMT). For instance, recent pathbreaking experiments in Very High Energy astrophysics (VHE), such as MAGIC and HESS, have used mainstream PMT technology (Aharonian et al, Astron Astrophys 492(1):L25-L28, 2008). Moreover the Cerenkov Telescope Array (CTA) which is now in its design phase, is also planed to be based on PMT's. However, there are some disadvantage...

  14. 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).

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

    OpenAIRE

    Groot, P.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 ...

  16. Different approaches to the thermonuclear fusion problem

    International Nuclear Information System (INIS)

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

  17. INVESTIGATION OF THE 0.84-M TELESCOPE GUIDING AT THE OAN-SPM

    OpenAIRE

    V. G. Orlov; Hiriart, D.; V. V. Voitsekhovich

    2014-01-01

    We report the results of experimental investigations of the 0.84-m telescope guiding at the Observatorio Astron ́mico Nacional at Sierra San Pedro M ́rtir, o a Mexico. The observations were carried out with an EMCCD Andor Luca-S camera which allows one to record sets of short-exposure images. The analysis of the data shows that three types of telescope guiding errors are present: linear trend, telescope vibrations, and telescope jumps.

  18. Los cometas de Atawallpa: acerca del papel de las profecías en la política del Estado Inka

    Directory of Open Access Journals (Sweden)

    Mariusz Ziólkowski

    1988-12-01

    Full Text Available En este artículo quisiera detenerme sólo sobre el eventual impacto que pudieron haber tenido el calendario estatal inca y las profecías basadas  en la interpretación de los fenómenos astronómicos extraordinarios, en la actitud que tomaron los dirigentes del Imperio, y especialmente Atawallpa, frente a los españoles.

  19. RF and microvawe plasma application for pre-sowing caryopsis treatments

    Czech Academy of Sciences Publication Activity Database

    Filatova, I.; Azharonok, V.; Kadyrov, M.; Beljavsky, V.; Šerá, Božena; Hrušková, Iveta; Špatenka, P.; Šerý, M.

    Belgrane : Publ. Astron. Obs, 2010 - (Popovic, L.; Kuraica, M.), s. 289-292 ISSN 0373-3742. [Summer School and International Symposium on the Physics of Ionized Gases /25./. Beograd (CS), 30.08.2010-03.09.2010] Institutional research plan: CEZ:AV0Z60870520 Keywords : seed modification * germination * seed desinfection * wheat * cold plasma * seedcoat Subject RIV: BL - Plasma and Gas Discharge Physics

  20. 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.

  1. 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.

  2. 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

  3. Effect of wind and atmospheric pressure variations on the mean sea level of salt marshes and estuaries

    OpenAIRE

    Abarca, Juan M.; Muñoz-Perez, Juan J.

    2009-01-01

    Se presentan tres formulaciones para predecir las variaciones de largo periodo en el nivel del mar debidas no a la marea astronómica, sino a fenómenos meteorológicos como el viento y los cambios de presión tanto de carácter estacionario como dinámico. Para validar estas fórmulas, se analiza una serie de datos del nivel del mar de tres meses de duración tomada en dos puntos del caño de Sancti Petri separados 5 km entre sí. Se advierten importantes variaciones del nivel medio diario y se demues...

  4. The rotational temperature of the FeH molecules in a large sunspot

    Science.gov (United States)

    Fawzy, Diaa

    2009-11-01

    Equivalent widths for four FeH bands (0-0), (1-0), (2-0), and (2-1) versus rotational quantum number J have been used to determine the rotational temperature of the molecule. The average value obtained from the first three bands is Trot=2900K±300K. This result agrees well with the temperatures derived for other molecules in sunspot umbrae. The current value is notably higher than that obtained earlier by (Mulchaey, J.S., 1989. Pub. Astron. Soc. Pacific 101, 211) for the same molecule.

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

    OpenAIRE

    Gonzalo Maier

    2015-01-01

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

  6. Evaluación de una propuesta para la enseñanza y el aprendizaje de la astronomía en secundaria

    OpenAIRE

    Palomar Fons, Rafael; Solbes Matarredona, Jordi

    2015-01-01

    Este trabajo de investigación presenta una propuesta para la enseñanza de la astronomía enmarcada en el socioconstructivismo que se ha implementado en alumnos de secundaria de 17 años, realizando un diseño de tipo pre-test y post-test. El análisis de los datos ha revelado la propuesta como muy eficaz, mostrando una mejora significativa en prácticamente todos los ítems analizados. También se ha mostrado que, a pesar de partir con conocimientos astronómicos similares, los alumnos de la modalida...

  7. Uso didáctico de recursos tic y software libre en la enseñanza de la observación lunar

    OpenAIRE

    Peña Parra, Juan Carlos

    2013-01-01

    Actualmente existe una gran diversidad de opciones pedagógicas frente a la implementación de ambientes de aprendizaje para la Educación en Tecnología y las Ciencias en general, hecho que constituye una riqueza para las prácticas pedagógicas de los docentes. El objetivo de este trabajo es presentar una propuesta de actividades fundamentada en tres pilares para el estudio de la astronomía básica: coordenadas astronómicas, constelaciones y la Luna, en un contexto en el que se construyen los conc...

  8. VizieR Online Data Catalog: PISCO speckle observations in 2007 (Prieur+, 2009)

    Science.gov (United States)

    Prieur, J.-L.; Scardia, M.; Pansecchi, L.; Argyle, R. W.; Sala, M.

    2015-07-01

    The observations were carried out with the PISCO speckle camera with the ICCD (Intensified Charged Coupled Device) detector belonging to Nice University (France). This instrumentation is presented in Prieur et al. (1998, Exp. Astron., 8, 297) and our observing procedure is described in detail in Paper VI (Scardia et al., 2009AN....330...55S). For the present observations, thanks to an improvement of our software and a faster computer, we were also able to compute in real time the restricted triple correlation (Aristidi et al., 1997A&AS..125..139A), used for resolving the 180° ambiguity. (2 data files).

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

    OpenAIRE

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

    2014-01-01

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

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

    OpenAIRE

    Noyelles, B.

    2007-01-01

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

  11. 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

  12. Specification of APERTIF Polyphase Filter Bank in CλaSH

    OpenAIRE

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

    2012-01-01

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

  13. 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.

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

    CERN Document Server

    Murphy, Michael T; Flambaum, Victor V

    2007-01-01

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

  15. 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.)

  16. Matemática aplicada y relaciones de proporcionalidad

    OpenAIRE

    Ros, Rosa María

    1996-01-01

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

  17. Estudio e implementación de una herramienta probabilística para la Cross-identificación de objetos extragalácticos

    OpenAIRE

    Manjón García, Alberto

    2015-01-01

    RESUMEN: En este trabajo se ha implementado y estudiado la eficacia de un método probabilístico bayesiano de cross-identificación de objetos extragalácticos, basado en el formalismo teórico propuesto por Tamás Budavári y Alexander S. Szalay [1]. Esta herramienta es capaz de cotejar dos catálogos astronómicos obtenidos con instrumentos de distintas resoluciones angulares, como son el Observatorio Espacial Herschel y el proyecto GAMA, e incorpora no sólo información tanto de las distintas resol...

  18. A note on electromagnetic fields of a slowly rotating magnetized neutron star

    Science.gov (United States)

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

    2003-05-01

    Using the electromagnetic fields of an aligned rotating magnetic dipole in a Schwarzschild background, the fields and the surface and bulk charge densities had been computed for an obliquely rotating dipole by De Paolis, Qadir and Tarman (Nuovo Cimento B, 114 (1999) 11). Rezzolla, Ahmedov and Miller (Mon. Not. R. Astron. Soc., 322 (2001) 723) had argued that the analysis was not valid as the Kerr background should have been used. As such the charge density and fields obtained earlier needed to be recomputed using their analysis. This suggestion has been followed here.

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

    OpenAIRE

    Malonek, Helmuth R.; Kharlamova, Vera I.

    2010-01-01

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

  20. 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.

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

    OpenAIRE

    Mauro Callejas Cuervo Óscar Yovany Baquero Moreno

    2010-01-01

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

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

    OpenAIRE

    Mario R. Araiza Quijano; Irene Cruz-González

    2011-01-01

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

  3. Eventos del Claustro 2008

    OpenAIRE

    Galindo , Nicolás; Sandoval Andrade, Olga

    2008-01-01

    En esta Galería fotográfica se muestra los evento realizados por el Sistema de Patrimonio Cultural y Museos de la Universidad Nacional de Colombia durante el periodo 2008-2009. Entre el Fondo de Imágenes están La Maestría en Museología al igual que Exposiciones importantes como "Museo de la Historia de la Medicina", "Observatorio Astronómico Nacional", "Expedición Botánica", "Jorge Eliecer Gaitán" entre otras.

  4. Cartas del Observatorio N° 2

    OpenAIRE

    Castell, Edmon; Torres Carreño, Guillermo Andrés; Diazgranados, Carlos Nicolás; Mora, Yaneth

    2011-01-01

    El boletín del OAN, "Cartas del Observatorio", es una pieza de comunicación desarrollada entre el Observatorio Astronómico Nacional (OAN) y el Área de Comunicación del SPM. El boletín periódico forma parte de los aportes del SPM al Bicentenario de la Independencia (2010) de Colombia. Este segundo número de Cartas del Observatorio, describe la construcción del edificio, el plan museológico por parte del SPM, una de las piezas importante del OAN, la publicación de la infografía y la partici...

  5. Análisis y diseño electromagnético de detectores Kid para aplicaciones espaciales a frecuencias de THZ

    OpenAIRE

    Blázquez Valles, Beatriz

    2011-01-01

    La banda submilimétrica, o del infrarrojo lejano, es la porción del espectro electromagnético de la que menos información se tiene. La investigación de esta banda se ha convertido en un tema importante y de gran alcance tanto para aplicaciones espaciales como terrestres. Hasta la fecha, los dispositivos criogénicos eran los detectores más sensibles que existían para muchas de estas aplicaciones. Sin embargo, la siguiente generación de instrumentos astronómicos requiere de grandes campos de vi...

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

    OpenAIRE

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

    2013-01-01

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

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

    Science.gov (United States)

    Villanueva, J. R.; Olivares, Marco

    2015-11-01

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

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

    OpenAIRE

    Echevarría, J.

    2007-01-01

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

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

    International Nuclear Information System (INIS)

    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.)

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

    International Nuclear Information System (INIS)

    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

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

    OpenAIRE

    Dupey García, Elodie

    2013-01-01

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

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

    OpenAIRE

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

    2010-01-01

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

  13. Aspectos numéricos y gráficos de la derivada de orden superior

    OpenAIRE

    Cantoral, Ricardo; Sánchez, Mario; Molina, Juan Gabriel

    2007-01-01

    En este trabajo se muestran algunos resultados de nuestras indagaciones sobre los significados y representaciones asociados con la derivada de orden superior. Estos resultados se plantean en contextos numéricos y gráficos; y son el resultado del estudio de algunas propiedades matemáticas, y el análisis de fuentes primarias como la producción astronómica de Isaac Newton (Newton, 1687). El trabajo se inscribe en la línea de investigación denominada Pensamiento y Lenguaje Variacional (PyLV) (Can...

  14. 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.

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

    OpenAIRE

    Inacio, María Alejandra

    2010-01-01

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

  16. Galileo y los telescopios

    OpenAIRE

    Vela Herranz, Nacho

    2010-01-01

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

  17. 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?

  18. 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.

  19. El profesor Pedro Carrasco Garrorena

    Directory of Open Access Journals (Sweden)

    E. Piña

    2008-01-01

    Full Text Available Relaci ́ n de los aspectos m ́ s importantes de la vida acad ́ mica del profesor Pedro Carrasco Garrorena, Director durante la Guerra Civil del o a e ̃ Observatorio Astron ́ mico de Madrid y Decano de la Facultad de Ciencias de la Universidad de Madrid. Tuvo que dejar Espana al triunfo de o Francisco Franco por haber sido perseguido de forma excepcional. Lleg ́ en 1939 al M ́ xico que empezaba a nacer cient ́ficamente y sirvi ́ a o e ı o la ciencia en su plena madurez por medio de su c ́ tedra y sus libros cient ́ficos.

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

    Science.gov (United States)

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

    2016-05-01

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

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

    OpenAIRE

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

    2016-01-01

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

  2. 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.

  3. 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.

  4. Improved electron collisional line broadening for low-temperature ions and neutrals in plasma modeling

    International Nuclear Information System (INIS)

    In this study, electron collisional broadening of observed spectral lines depends on plasma electron temperature and density. Including this effect in models of measured spectra is necessary to determine plasma conditions; however, computational limits make accurate line broadening treatments difficult to implement in large-scale plasma modeling efforts. In this paper, we report on improvements to the treatment of electron collisional line broadening and illustrate this with calculations using the Los Alamos ATOMIC code. We implement the Dimitrijevic and Konjevic modified semi-empirical model Dimitrijevic and Konjevic (1986 Astron. and Astrophy. 163 297 and 1987 Astron. Astrophys. 172 345), which we amend by employing oscillator strengths from Hartree-Fock calculations. This line broadening model applies to near-neutral plasmas with electron temperatures of Te ~ 1 eV and electron densities of Ne ~1017 cm-3. We evaluate the D.K.-inspired model against the previous hydrogenic approach in ATOMIC through comparison to NIST-rated measurements for selected neutral and singly-ionized Ca, O, Fe, and Sn lines using both fine-structure and configuration-averaged oscillator strengths. The new D.K.-inspired model is significantly more accurate than the previous hydrogenic model and we find the use of configuration-averaged oscillator strengths a good approximation for applications such as LIBS (laser induced breakdown spectroscopy), for which we demonstrate the use of the D.K.-inspired model

  5. 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)

  6. 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.

  7. The McLean-Watson line strength formula and its implementation

    International Nuclear Information System (INIS)

    We consider the application of the line strength formula recently derived by Watson (2006 J. Phys. B: At. Mol. Opt. Phys. 39 L291) to transitions between states of high principal quantum number in hydrogenic atoms and ions (Rydberg-Rydberg transitions). Apparent difficulties in the implementation of this formula are overcome by the use of recurrence relations derived by the ladder operator technique of Infeld and Hull (1951 Rev. Mod. Phys. 23 21), and set out in an earlier paper by the present author (2006 J. Phys. B: At. Mol. Opt. Phys. 39 2641). The use of the McLean-Watson formula for such cases is illustrated by the determination of the radiative lifetimes for levels with n ∼ 1000 and comparison of present results with approximate formulae. Interest in this work on the radial matrix elements for large n and n' is related both to measurements of radio recombination lines from tenuous space plasmas, e.g. Stepkin et al (2007 Mon. Not. R. Astron. Soc. 374 852) and to the calculation of Stark broadening for such spectra, e.g. Gigosos et al (2007 Astron. Astrophys. 466 1189), Stambulchik et al (2007 Phys. Rev. E 75 016401) and Stambulchik and Maron (2008 J. Phys. B: At. Mol. Opt. Phys. 41 095703). In addition, we discuss the question of inaccuracy caused by the omission of fine structure in such calculations, and the numerical stability of the recurrence relations used to implement the line strength formulae.

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

    Science.gov (United States)

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

    2016-07-01

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

  9. 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...

  10. 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.

  11. 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.

  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. 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.

  14. 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

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

    Science.gov (United States)

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

    2015-08-01

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

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

    Science.gov (United States)

    Irwin, Mike J.; Lewis, Geraint F.

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

  17. 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.

  18. 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.

  19. 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.

  20. 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.

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

    Directory of Open Access Journals (Sweden)

    Gonzalo Maier

    2015-12-01

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

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

    OpenAIRE

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

    2014-01-01

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

  3. Ion induction linacs: reference design and proposed test-bed

    International Nuclear Information System (INIS)

    The LBL HIF program has concentrated on the induction linac approach because this type of machine is able to accelerate the entire charge required for fusion in a single, high current bunch, and because of our experience ten years ago using the Astron induction linac at LLL and subsequently building and operating our own machine at LBL. The operation of an rf linac with storage rings is based on an operating line where, excluding the tree of linacs at the lowest energies, acceleration is along a constant current trajectory to peak energy, and then along a constant energy trajectory as the current is compressed and multiplied to reach the required of beam power (> 100 TW). The operation of the linear induction accelerator is along a trajectory where the energy and current are increased simultaneously; at the end of acceleration the beam is split transversely into two groups of beams to provide for higher peak power and a left-right symmetrical pellet bombardment

  4. Universal density profile for cosmic voids.

    Science.gov (United States)

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

    2014-06-27

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

  5. 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.

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

    OpenAIRE

    Hernández Fernández, Antonio

    2014-01-01

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

  7. 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.

  8. 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.

  9. 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

  10. 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.

  11. 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.

  12. Organización y creación del Museo de Física de la Universidad Nacional de La Plata

    OpenAIRE

    Santamaría, Mariana

    2010-01-01

    El Instituto de Física constituía una de las secciones en que se dividía originalmente la Facultad de Ciencias Físicas y Matemáticas y era uno de los centros de altos estudios y de investigación en el cuál se manifestaba el espíritu de la UNLP. Creado como dependencia del Observatorio Astronómico funcionaba en un local en la calle 5 y 46 bajo la dirección del ingeniero uruguayo Tebaldo Ricaldoni (1906 – 1909). En 1906, la U.N.L.P puso a disposición de Ricaldoni importantes recursos para es...

  13. International data transfer for space very long baseline interferometry

    Science.gov (United States)

    Wiercigroch, Alexandria B.

    1994-11-01

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

  14. Physics of collisionless phase mixing

    CERN Document Server

    Tsiklauri, D

    2008-01-01

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

  15. Spectroscopic aperture biases in inside-out evolving early-type galaxies from CALIFA

    Science.gov (United States)

    Gomes, J. M.; Papaderos, P.; Vílchez, J. M.; Kehrig, C.; Iglesias-Páramo, J.; Breda, I.; Lehnert, M. D.; Sánchez, S. F.; Ziegler, B.; Dos Reis, S. N.; Bland-Hawthorn, J.; Galbany, L.; Bomans, D. J.; Rosales-Ortega, F. F.; Walcher, C. J.; García-Benito, R.; Márquez, I.; Del Olmo, A.; Mollá, M.; Marino, R. A.; Catalán-Torrecilla, C.; González Delgado, R. M.; López-Sánchez, Á. R.; Califa Collaboration

    2016-02-01

    Integral field spectroscopy (IFS) studies based on CALIFA survey data have recently revealed ongoing low-level star formation (SF) in the periphery of a small fraction (~10%) of local early-type galaxies (ETGs), witnessing a still ongoing inside-out galaxy growth process. A distinctive property of the nebular component in these ETGs, classified i+, is a structure with two radial zones, the inner of which displays LINER emission with a Hα equivalent width EW(Hα) ≃ 1 Å, the outer (3 Å growth or inside-out SF quenching, and might be of considerable relevance to galaxy taxonomy and studies of the cosmic SFR density as a function of z. 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).

  16. 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.

  17. Survey of intense Sun-Earth Connection Events during Solar Cycle 23 (1995-2003)

    Science.gov (United States)

    Farrugia, C.; Matsui, H.; Kucharek, H.; Jordanova, V.; Smith, C.; Berdichevsky, D.; Torbert, R.

    In this work we compute in a specific formulation (Perreault and Akasofu, 1978) the energy extracted by the magnetosphere from the solar wind and the powering of the magnetosphere by the solar wind for the period 1995-2003 (i.e. 9 years), starting from the approach to the last solar minimum up to the approach to the coming solar minimum. We examine the largest events in terms of the interplanetary structures involved. We then correlate these with the strength of geomagnetic disturbances they elicited, as measured by the Dst index, corrected for magnetopause currents, and the auroral electrojects. The violent Sun-Earth Connection events of October - November 2003 are finally examined in this broader context. Perreault, P. and S.-I. Akasofu, A study of geomagnetic storms, Geophys. J. R. Astron. Soc, 54,} 547, 1978. This work is partially supported by NASA grants NAG5-10883, and NAG5-13512.

  18. 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.

  19. Síntese de genes de novo

    OpenAIRE

    Fernandes, Joana Pinto

    2011-01-01

    Devido ao facto do código genético ser degenerado, uma proteína composta por 300 aminoácidos, pode ser codificada por um valor verdadeiramente astronómico de mais de 10150 combinações de codões; mais do que o número estimado de átomos no Universo observável. Contudo, a escolha entre codões sinónimos na sequência de mRNA não é aleatória, mas pelo contrário, segue regras e apresenta funções importantes ao nível da precisão e eficiência de tradução, bem como no folding co-traducional de proteina...

  20. 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.

  1. 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.

  2. Atlas of monochromatic images of planetary nebulae

    Science.gov (United States)

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

    2016-08-01

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

  3. 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.

  4. 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.

  5. 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...

  6. 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).

  7. Rigorous estimates for the relegation algorithm

    Science.gov (United States)

    Sansottera, Marco; Ceccaroni, Marta

    2016-07-01

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

  8. Anomalous Earth flybys of spacecraft

    Science.gov (United States)

    Wilhelm, Klaus; Dwivedi, Bhola N.

    2015-07-01

    A small deviation from the potential is expected for the gravitational interaction of extended bodies. It is explained as a consequence of a recently proposed gravitational impact model (Wilhelm et al. in Astrophys. Space Sci. 343:135-144, 2013) and has been applied to anomalous perihelion advances by Wilhelm and Dwivedi (New Astron. 31:51-55, 2014). The effect—an offset of the effective gravitational centre from the geometric centre of a spherical symmetric body—might also be responsible for the observed anomalous orbital energy gains and speed increases during Earth flybys of several spacecraft. However, close flybys would require detailed considerations of the orbit geometry. In this study, an attempt is made to explain the anomalous Earth flybys of the Galileo, NEAR Shoemaker and Rosetta spacecraft.

  9. 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

  10. Keplerian frequency of uniformly rotating neutron stars in relativistic mean field theory

    International Nuclear Information System (INIS)

    Adopting the equation of states (EOSs) from the relativistic mean field (RMF) theory, the relationships among the Keplerian frequency fK, gravitational mass M and radius R for the rapidly rotating neutron stars with and without hyperons are presented and analyzed. For various RMF EOSs, the empirical formula fK (M) = 1.08 (M/M⊙)1/2(Rs/10 km)-3/2 kHz, proposed by P. Haensel et al. [Astron. Astrophys.502 (2009) 605], is found to be an approximation with the error at most 13% and such approximation is worse for the neutron stars with hyperons. It indicates that the errors should be considered when the empirical formula is used to discuss the properties of neutron stars. (author)

  11. Experimental investigation of the trapping and energy loss mechanisms of intense relativistic electron rings in hydrogen gas and plasma

    International Nuclear Information System (INIS)

    The results of an experimental study on the trapping and energy loss mechanisms of intense, relativistic electron rings confined in Astron-like magnetic field geometries are presented. The work is subdivided into four sections: gas trapping; average ring electron energetics; plasma trapping, and hollow-beam cusp-injection into gas and plasma. The mechanisms by which the injected beam coalesces into a current ring in the existing Cornell RECE-Berta facility are considered. To investigate the nature of ring electron energy loss mechanisms following completion of the trapping process, a diagnostic was developed utilizing multi-foil X-ray absorption spectroscopy to analyze the Bremsstrahlung generated by the electrons as they impinge upon a thin tungsten wire target suspended in the circulating current. Finally, a set of preliminary experimental results is presented in which an annular electron beam was passed through a coaxial, non-adiabatic magnetic cusp located at one end of a magnetic mirror well

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

    Institute of Scientific and Technical Information of China (English)

    Wang Guo-Li; Zhou Xiao-Xin

    2009-01-01

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

  13. Extended radio sources and elliptical galaxies. IV. Structures of 40 resolved sources

    International Nuclear Information System (INIS)

    Partial-synthesis maps are presented for a sample of extended radio galaxies at 2.7 and 8.1 GHz. These maps were used to determine the overall sizes, orientations, and gross morphologies of the sources during a study of the relative orientations of extended radio sources and their parent elliptical galaxies. The optical identifications of 13 sources have been confirmed by the detection of small-diameter radio components within their parent galaxies. Two radio galaxies in this group: 0238+085 and 1250-102: have extended radio cores and elongated structures suggestive of two-sided radio jets similar to those of 3C449, NGC 315, and 3C31. The spectrum-luminosity relation found for extended radio cores in Paper I ]Bridle, A. H., and Fomalont, E. B. [Astron. J. 83, 704 (1978)

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 15N/14N Ratio Determination in the ISM with Herschel with High Resolution Spectroscopy of Nitrogen Radicals

    Science.gov (United States)

    Margulès, L.; Bailleux, S.; Wlodarczak, G.; Pirali, O.; Martin-Drumel, M.-A.; Roy, P.; Roueff, E.; Gerin, M.

    2011-06-01

    The very high resolution of the HIFI instrument (134 kHz-1MHz) on board of Herschel needs very accurate laboratory measurements to detect unambiguously the signature of stable and unstable molecular species. Concerning the pure rotation spectra of new species, and particularly of open shell molecules, the first prediction could be far away and up to few hundred MHz. The 15N/14N ratio is not well measured in the ISM. However, the 15N/14N in the isotopomers is a potential tracer of the formation processes and the possible link with cometary molecules. Recent measurements include the detection of 15NH_2D N15NH+ and 15NH_3. The NH and NH_2 species are the simplest nitrogen radicals and are intermediate products in the NH_3 synthesis. They have been easily detected by Herschel and it therefore is interesting to now search for 15NH and 15NH_2. No spectrocopic data have been reported for these two radicals up to now. We present here the studies with high resolution spectroscopy in the THz range. The high sensitivity and the wide range of Synchrotron (0.6-6 THz) was essential to improve the prediction of the spectra of these two species in order to measure them in Lille (0.6-1 THz) with both a higher accuracy and resolution. The combined studies now give the most accurate predictions. ISM searches on these radicals are in progress in the HERSCHEL spectra. This work is supported by the Programme National de Physico-Chimie du Milieu Interstellaire (PCMI-CNRS) M. Gerin, N. Marcellino, N. Biver, et al., Astron. & Astrophys. 498 (2009) 9. L. Bizzochi, P. Caselli, and L. Dore, Astron. & Astrophys. 510 (2010) L5. D. C. Lis, A. Wooten, M. Gerin and E. Roueff, Astrophys. J. 710 (2010) L49.

  20. Is the Be star theta CrB an eclipsing binary

    International Nuclear Information System (INIS)

    The analysis of 19 published radial velocity measurements of the broad H I and He I lines covering the time span 1904 to 1979 indicates that theta CrB may be a long-periodic spectroscopic binary with an orbital period of 510.87 days. The predicted time of a hypothetical primary eclipse from the orbital solution coincides remarkably well with the 0.7/sup m/ deep photometric minimum observed by Roark (1971, Astron. J. 76, 634). It is argued that the proposal by Roark et al. (1972, Astrophys. Lett. 10, 55), i.e. that the visual companion to theta CrB, discovered by Couteau (1971, IAU Circ. 2339), is responsible for this light variation, is untenable. It may also be significant that the unusual disappearance of the C IV lines in the UV spectrum of theta CrB, reported by Doazan et al. (1983, preprint) occurred around the time of the predicted primary eclipse. Highly speculative conclusions, which should be subjected to critical tests by future observations and quantitative analyses of archival data, are: 1. theta CrB is a triple system, consisting of a spectroscopic eclipsing binary with P=510.87 days, and a distant visual companion with P>45 years. 2. Light variations observed by Roark (1971, Astron. J. 76, 634) are interpreted as a superimposition of an (atmospheric) eclipse of the primary, and of rapid physical variations of the spectroscopic secondary, detectable only during eclipses. 3. The next primary eclipse is expected to occur on May 25 to June 15, 1984. (author)

  1. Projeto observatórios virtuais: educação através de telescópios robóticos

    Science.gov (United States)

    Santana, P. H. S.; Shida, R. Y.

    2003-08-01

    O principal objetivo do projeto Observatórios Virtuais é o ensino na área de ciências através de atividades práticas desenvolvidas em colaboração entre instituições de pesquisa em astronomia e escolas de ensino médio e fundamental. Este ano deverá ser concluída a implantação do programa piloto de estudos, pesquisas e observação astronômica direta, com utilização em tempo real de telescópios robóticos, que assim funcionarão como "observatórios virtuais". O objetivo pedagógico das atividades práticas baseadas nas imagens atronômicas é desenvolver as habilidades e competências dos alunos no uso do método científico. Para isso, serão realizados projetos interdisciplinares, a partir de observações astronômicas, já que a astronomia é uma área interdisciplinar por excelência. Essas atividades terão níveis diferenciados de complexidade, que podem ser adequados aos vários graus do ensino e realidades regionais. Será dada ênfase ao desenvolvimento e aplicação em São Paulo, onde atua a equipe do IAG/USP. Como resultados apresentados no presente trabalho, temos a criação de um software em português para o processamento de imagens obtidas através de CCDs e a elaboração de material para as atividades educacionais relacionadas.

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

    International Nuclear Information System (INIS)

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

  3. Testing cosmology from fundamental considerations: Is the Friedmann universe intrinsically flat

    Science.gov (United States)

    Mitra, Abhas

    2014-02-01

    Recently Melia and Shevchuk (Mon Not R Astron Soc 419:2579,2012) (MS) have proposed the so-called cosmology where the "Gravitational Horizon" of the universe is equal to the distance travelled by light since "Big Bang". Here we would like to see whether the basic claim is correct or not because MS have not given any cogent derivation for the same. Essentially we will compare the twin expressions for the Einstein energy momentum complex (EMC) of the Friedmann universe obtained by using an appropriate superpotential and also by a direct method. To enable a meaningful comparison of the twin expressions, both are computed by using the same quasi-Cartesian coordinates. We however do not claim that Einstein EMC is superior to many other routes of defining EM of a self-gravitating system. In fact, for static isolated spherical syatems, the idea of a coordinate independent field energy of Lynden-Bell and Katz (Mon Not R Astron Soc 213:21, 1985) might be quite physically significant. Yet, here, we use Einstein EMC because (i) our system is non-static and not isolated one (ii) our primary aim is not find any absolute value of EM, and, finally, (iii) only Einstein pseudo-tensor offers equivalent twin expressions for EM which one can be equated irrespective of any physical significance. Following such comparison of equivalent twin expressions of Einstein energy, we find an exact proof as to why Friedmann universe must be spatially flat even though, mathematically one can conceive of curved spaces in any dimension. Additionally, it follows that, apparently, the scale factor as insisted by proposition. Nonetheless, because of close similarity of this form, , with the (vacuum) Milne metric, and also because of implied unphysical equation of state, cosmology is unlikely to represent the physical universe.

  4. Light bending in f(T) gravity

    Science.gov (United States)

    Ruggiero, Matteo Luca

    2016-05-01

    In the framework of f(T) gravity, we focus on a weak-field and spherically symmetric solution for the Lagrangian f(T) = T + αT2, where α is a small constant which parametrizes the departure from general relativity (GR). In particular, we study the propagation of light and obtain the correction to the general relativistic bending angle. Moreover, we discuss the impact of this correction on some gravitational lensing observables, and evaluate the possibility of constraining the theory parameter α by means of observations. In particular, on taking into account the astrometric accuracy in the Solar System, we obtain that |α|≤ 1.85 × 105m2; this bound is looser than those deriving from the analysis of Solar System dynamics, e.g. |α|≤ 5 × 10‑1m2 [L. Iorio, N. Radicella and M. L. Ruggiero, J. Cosmol. Astropart. Phys. 1508 (2015) 021, arXiv:1505.06996 [gr-qc].], |α|≤ 1.8 × 104m2 [L. Iorio and E. N. Saridakis, Mon. Not. R. Astron. Soc. 427 (2012) 1555, arXiv:1203.5781 [gr-qc].] or |α|≤ 1.2 × 102m2 [Y. Xie and X. M. Deng, Mon. Not. R. Astron. Soc. 433 (2013) 3584, arXiv:1312.4103 [gr-qc].]. However, we suggest that, since the effect only depends on the impact parameter, better constraints could be obtained by studying light bending from planetary objects.

  5. 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.

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

    Science.gov (United States)

    Toma, Kenji; Takahara, Fumio

    2016-06-01

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

  7. 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

  8. 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

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

    Directory of Open Access Journals (Sweden)

    Márcio Balbino Cavalcante

    2012-12-01

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

  10. 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

  11. Origin and Evolution of the Cometary Reservoirs

    Science.gov (United States)

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

    2015-12-01

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

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

    Science.gov (United States)

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

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

  13. Impact and cratering rates onto Pluto

    Science.gov (United States)

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

    2015-09-01

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

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

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    E. Graham

    2011-01-01

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

  15. 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

  16. 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)

  17. 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

  18. 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

  19. 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.

  20. 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

  1. Water, heat, bombardment: The evolution and current state of (2) Pallas

    Science.gov (United States)

    Schmidt, Britney Elyce; Castillo-Rogez, Julie C.

    2012-03-01

    Using recent constraints on the shape and density of (2) Pallas, we model the thermal evolution of the body as a function of possible formation scenarios that differ in the time of formation and composition assumed for the protoplanet. We develop possible evolution scenarios for Pallas and compare these to available observations. Our models imply two distinct types of end states: those with a hydrosphere and silicate core, and those where the body is dominated by hydrated silicates. We show that for an initial ice-rock mixture with density 2400 kg/m3, Pallas is likely to differentiate and form a rocky core and icy shell. If Pallas accreted from material with lower initial ice content, our models indicate that Pallas’s interior is dominated by hydrated silicates, possibly with a core of anhydrous silicates. We also investigate the possibility that Pallas’s initial density was similar to Ceres’, i.e., that it formed from an ice-rock mixture of density 2100 kg/m3. This implies that the object lost a significant fraction of its hydrosphere as a consequence of thermal oscillations and impacts, a distinct possibility given its density, evidence for impact excavation and current orbital parameters. Its blue spectral slope and observed surface variation may also be evidence for such a process (e.g. Jewitt, D.C. [2002]. Astron. J. 123, 1039-1049; Schmidt, B.E. et al. [2009]. Science 326, 275-279; Yang, B., Jewitt, D. [2010]. Astron. J. 140, 692-698). If Pallas still contains a thin layer of water ice, then that layer corresponds to the bottom of a former icy shell, and as such, could be enriched in non-ice materials such as organics. We evaluate the likeliness of each scenario and show the general magnitude of water loss processes for Pallas. Given a balance of observational and theoretical constraints, we favor a water-rich accretion for Pallas that implies that Pallas has lost a significant fraction of its initial water content through exogenic processes since its

  2. Global spectral energy distributions of the Large Magellanic Cloud with interstellar dust

    Science.gov (United States)

    Kim, Sungeun; Kwon, Eunjoo; Jeong, Kyoung-Sook; Kim, Kihun; Cho, Chiyoung; Chung, Eun Jung

    2014-01-01

    The effects of dust on infrared emission vary among galaxies of different morphological types. We investigated integrated spectral energy distributions (SEDs) in infrared and submillimeter/millimeter emissions from the Large Magellanic Cloud (LMC) based on observations from the Herschel Space Observatory (HSO) and near- to mid-infrared observations from the Spitzer Space Telescope (SST). We also used IRAS and WMAP observations to constrain the SEDs and present the results of radiative transfer calculations using the spectrophotometric galaxy model. We explain the observations by using dust models with different grain size distributions in the interstellar medium of the LMC, noting that the LMC has undergone processes that differ from those in the Milky Way. We determined a spectral index and a normalization factor in the range of -3.5 to -3.45 with grain radii in the range of 1 nm-300 nm for the silicate grain and 2 nm-1 μm for the graphite grain. The best fit to the observed SED was obtained with a spectral index of -3.47, similar to the value derived by Piovan et al. (Mon. Not. R. Astron. Soc. 366(3):923, 2006a). The grain size distribution is described using a power law but with a break that is introduced below a b , where a larger exponent is used. Changing the graphite grain size distribution significantly changed the SED pattern within the observational uncertainties. Based on the SED fits to the observations from submillimeter wavelengths to infrared radiation from the LMC using GRASIL (Silva et al., Astrophys. J. 509(1):103, 1998), we obtained a reasonable set of parameter values in chemical and geometric space together with the grain size distributions (Weingartner and Draine, Astrophys. J. 548(1):296, 2001) and a modified MRN model with the LMC extinction curve (Piovan et al., Mon. Not. R. Astron. Soc. 366(3):923, 2006a). For a given set of parameters including the disc scale height, synthesis of the starlight spectrum, optical depth, escape time scale

  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. Lab Astro and the Origins of the Chemical Elements

    Science.gov (United States)

    Lawler, James E.

    2010-03-01

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

  5. 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.

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

    Science.gov (United States)

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

    2015-08-01

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

  7. The Future of Astrometric Education

    Directory of Open Access Journals (Sweden)

    William van Altena

    2006-01-01

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

  8. 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.

  9. 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.

  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. 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.

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

    International Nuclear Information System (INIS)

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

  13. The LOFAR Pulsar Data Pipeline

    Science.gov (United States)

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

    2010-12-01

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

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

    International Nuclear Information System (INIS)

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

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

  16. Phantom crossing with collisional matter in f(T) gravity

    Science.gov (United States)

    Zubair, M.

    2016-02-01

    We study the late-time cosmological evolution of f(T) (where T is the torsion scalar) theories with matter contents consisting of collisional self-interacting matter and radiations. The power law, exponential and logarithmic f(T) models are considered to explore the evolution of Hubble parameter H(z), dark energy (DE) equation of state (EoS) ωDE and effective EoS parameter ωeff. We show that crossing of phantom divide line can be realized in the presence of collisional matter as compared to the results obtained for the choice of noncollisional matter [K. Bamba, C.-Q. Geng, C.-C. Lee and L.-W. Luo, J. Cosmol. Astropart. Phys. 01 (2011) 021; K. Bamba, C.-Q. Geng and C.-C. Lee, arXiv:1008.4036]. The evolutionary behavior of ωDE is consistent with the one developed in [P. Wu and H. Yu, Eur. Phys. J. C 71 (2011) 1552] and recent observational data [U. Alam, V. Sahni and A. A. Starobinsky, J. Cosmol. Astropart. Phys. 0406 (2004) 008; S. Nesseris and L. Perivolaropoulos, J. Cosmol. Astropart. Phys. 0701 (2007) 018; P. Wu and H. Yu, Phys. Lett. B 643 (2006) 315; U. Alam, V. Sahni and A. A. Starobinsky, J. Cosmol. Astropart. Phys. 0702 (2007) 011; H. K. Jassal, J. S. Bagla and T. Padmanabhan, Mon. Not. R. Astron. Soc. 405 (2010) 2639].

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

    CERN Document Server

    Best, P N

    2008-01-01

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

  18. 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.

  19. 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.

  20. Electron-impact excitation of H-like Fe at high temperatures

    International Nuclear Information System (INIS)

    There have been two previous works concerning the electron-impact excitation of H-like Fe employing the R-matrix technique. The calculations by Aggarwal and Kingston (Aggarwal K M and Kingston A E 1993 Astrophys. J. Suppl. Ser. 85 187-95) were carried out non-relativistically in LS coupling while those of Kisielius et al (Kisielius R, Berrington K A and Norrington P H 1996 Astron. Astrophys. Suppl. Ser. 118 157-62) allowed for relativistic effects by using the Dirac-Fock R-matrix method. There seems to general agreement about values of the effective collision strength up to about 106 K in temperature with Kisielius et al, but close inspection of the collision strengths for dipole transitions shows that they do not have the correct high-temperature form. We have carried out a new (Breit-Pauli) R-matrix calculation combined with close attention to high-energy behaviour and radiation damping (not included in the previous works). We present and discuss our results for improved effective collision strengths for the temperature range 106-108.5 K - the peak coronal fractional abundance of Fe25+ lies at ∼ 108 K. (author)

  1. 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

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

    Science.gov (United States)

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

    2016-08-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Schrader, Stefan, E-mail: stefan.schrader@vti.bund.d [Johann Heinrich von Thuenen-Institute (vTI), Federal Research Institute for Rural Areas, Forestry and Fisheries, Institute of Biodiversity, Bundesallee 50, 38116 Braunschweig (Germany); Bender, Juergen; Weigel, Hans-Joachim [Johann Heinrich von Thuenen-Institute (vTI), Federal Research Institute for Rural Areas, Forestry and Fisheries, Institute of Biodiversity, Bundesallee 50, 38116 Braunschweig (Germany)

    2009-12-15

    A 2-year open-top chamber experiment with field-grown winter wheat (Triticum aestivum L. cv. Astron) was conducted to examine the effects of ozone on plant growth and selected groups of soil mesofauna in the rhizosphere. From May through June in each year, plants were exposed to two levels of O{sub 3}: non-filtered (NF) ambient air or NF+ 40 ppb O{sub 3} (NF+). During O{sub 3} exposure, soil sampling was performed at two dates according to different plant growth stages. O{sub 3} exposure reduced above- and below-ground plant biomass in the first year, but had little effect in the second year. The individual density of enchytraeids, collembolans and soil mites decreased significantly in the rhizosphere of plants exposed to NF+ in both years. Differences were highest around anthesis, i.e. when plants are physiologically most active. The results suggest that elevated O{sub 3} concentrations may influence the dynamic of decomposition processes and the turnover of nutrients. - Ozone reduced the individual densities of enchytraeids, collembolans and soil mites in the rhizosphere of winter wheat indirectly via the plant-soil-system.

  4. 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

  5. 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.

  6. 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.

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

    Directory of Open Access Journals (Sweden)

    M. G. Richer

    2010-01-01

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

  8. An integral field spectroscopic survey for high redshift damped Lyman-α galaxies

    Science.gov (United States)

    Christensen, L.; Wisotzki, L.; Roth, M. M.; Sánchez, S. F.; Kelz, A.; Jahnke, K.

    2007-06-01

    Aims:We search for galaxy counterparts to damped Lyman-α absorbers (DLAs) at z > 2 towards nine quasars, which have 14 DLAs and 8 sub-DLAs in their spectra. Methods: We use integral field spectroscopy to search for Lyα emission line objects at the redshifts of the absorption systems. Results: Besides recovering two previously confirmed objects, we find six statistically significant candidate Lyα emission line objects. The candidates are identified as having wavelengths close to the DLA line where the background quasar emission is absorbed. In comparison with the six currently known Lyα emitting DLA galaxies the candidates have similar line fluxes and line widths, while velocity offsets between the emission lines and systemic DLA redshifts are larger. The impact parameters are larger than 10 kpc, and lower column density systems are found at larger impact parameters. Conclusions: Assuming that a single gas cloud extends from the QSO line of sight to the location of the candidate emission line, we find that the average candidate DLA galaxy is surrounded by neutral gas with an exponential scale length of ~5 kpc. Based on observations collected at the Centro Astronómico Hispano Alemán (CAHA), operated by the Max-Planck Institut für Astronomie and the Instituto Astrofisica de Andalucia (CSIC). Full Fig. [see full text] is only available in electronic form at http://www.aanda.org

  9. Divulgación del Programa Consolider-GTC

    Science.gov (United States)

    Ruiz Zelmanovitch, N.; Mass Hesse, M.; Alfaro, E.

    2013-05-01

    The Gran Telescopio Canarias (GTC) is the biggest telescope of its class in the world. The CONSOLIDER INGENIO 2010-GTC project, First Science with the GTC: Spanish Astron- omy on the Forefront of the European Astronomy, funded by the Spanish Ministry of Science and Innovation, MICINN (now the Ministry of Economy and competitiveness, MINECO) has used the GTC to: (i) obtain leading science with its data, (ii) increase the involvement of the Spanish astronomical community in developing astronomical instrumentation, (iii) get an important Spanish participation in the new extremely large telescopes generation (ELTs), and (iv) make outreach and communicating to the society the main results. The project CONSOLIDER INGENIO 2010-GTC is structured and defined by objectives: 1) GTC: To optimize the GTC and its instruments; 2) SCIENCE: To develop leading science with the GTC; 3) E-ELT: To take advantage of the technological experience obtained with the GTC for the new generation of giant telescopes; 4) INSTRUMENTATION: To promote the Spanish participation in the new instrument developments for the GTC, VLT and the future ELTs; 5) EDUCATION: International School for Advanced Instrumentation (IScAI); and 6) OUTREACH: Outreach and communication of the project scientific results. This poster resumes five years of science communication around the Consolider-GTC project.

  10. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Garaud, Pascale, E-mail: pgaraud@ucsc.edu [Department of Applied Mathematics and Statistics, Baskin School of Engineering, University of California at Santa Cruz, 1156 High Street, Santa Cruz, California 95064 (United States); Gallet, Basile [Service de Physique de l’Etat Condensé, DSM/IRAMIS, CNRS UMR 3680, CEA Saclay, 91191 Gif-sur-Yvette cedex (France); Bischoff, Tobias [Division of Geological and Planetary Sciences, California Institute of Technology, Mail Code 170-25, 1200 E. California Blvd., Pasadena, California 91125 (United States)

    2015-08-15

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

  12. Mercury's resonant rotation from secular orbital elements

    Science.gov (United States)

    Stark, Alexander; Oberst, Jürgen; Hussmann, Hauke

    2015-11-01

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

  13. 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

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

    International Nuclear Information System (INIS)

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

  15. 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.

  16. 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.

  17. Interpretation of the burst spectra from X-ray burster MXB 1728-34 with allowance for Thomson scattering

    International Nuclear Information System (INIS)

    Spectral evolution is investigated and interpretations of the spectra are considered for a burst from the X-ray burster MXB 1728-34 detected by ASTRON. Interpretation of the burst spectra in terms of black.body radiation leads to improbably small neutron star (NS) mass M and radius R as well as distance D to the burster. Interpretation of the spectra around the burst maximum (first ≅4 s) in terms of radiation from an isothermal NS photosphere with dominating role of the Thomson scattering allows one to obtain reasonable constraints on M, R, and D (in particular, M=(1.4-2) M Sun, R=(6.5-12) km for D=6 kpk and helium photosphere). This interpretation leads to a conclusion that the photosphere expands up to several tens of kilometers in the burst maximum. The luminosity remains close to the Eddington limit during expansion and contraction; maxima of the observed flux corresponding to minima of the luminosity due to general relativity effects. The burst tail spectra are close to those of thermal bremstrahlung. Such spectra might originate in a corona around NS with mass ∼ 10 -16 MSun, radius ∼ 100 km and electron density ∼ 1019 cm-3, or in a hot layer with thickness ∼ 1-10 gxcm-2 on the photosphere

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

    International Nuclear Information System (INIS)

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

  19. A Short History of Hindu Astronomy & Ephemeris

    CERN Document Server

    Rudra, P

    2009-01-01

    We have summarized here the astronomical knowledge of the ancient Hindu astronomers. This knowledge was accumulated from before 1500 B.C. up to around 1200 A.D. In Section \\ref{equiv} we have correlated terms used by the Hindu astronomers and their equivalents in modern astronomy. In Section \\ref{coord} we have defined the different astronomical coordinate systems and their transformation relations. In Sections \\ref{seasons} and \\ref{cycles} we have collected the main features of solar and lunar motions in terms of modern astronomical terminology. In Section \\ref{stars} we have given the names of the stars mentioned by the Hindu astronomers and their modern names with the present astronomical coordinates. In Section \\ref{hist} we have given a short survey of Indian history with emphasis to Hindu astronomy. In Sections \\ref{vedas} and \\ref{sid} we have given short descriptions of the main sources of Hindu astronomy. In Section \\ref{astron} the important features of Hindu astronomy have been described. All thro...

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

    International Nuclear Information System (INIS)

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

  1. 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

  2. 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.

  3. 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.

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

    Science.gov (United States)

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

    2014-10-01

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

  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. 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.

  7. 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...

  8. 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.

  9. Submillimeter Wave Spectroscopy and ISM Search for a Chiral Molecule : 2-AMINOPROPANENITRILE

    Science.gov (United States)

    Margulès, L.; Motiyenko, R.; Mollendal, H.; Guillemin, J.-C.; Belloche, A.

    2010-06-01

    The detection of chiral compounds in the interstellar medium is a great challenge and could tell us the connection between the chemistry of the ISM and the origin of life on the primitive Earth. Chiral C-3 sugar, α-aminonitriles and cyanohydrins or the corresponding chloro-derivatives are intuitively the simplest chiral candidates consistent with the nature of the heteroatoms observed in the ISM. The aminoacetonitrile being observed in Sgr B2(N) but not the simplest cyanohydrins and chloacetonitrile, our study was devoted to the 2-aminopropanenitrile, the methyl derivative of aminoacetonitrile and the precursor of alanine (an amino acid) by hydrolysis. The measurements were made in Oslo and in Lille from 7 to 660 GHz. More than 2000 lines were assigned. The search in Sgr B2(N) has been unsuccessful so far. The upper limit currently derived on the column density is comparable to the column density of aminoacetonitrile. This work is supported by the french Programme National de Physique Chimie du Milieu Interstellaire A. Belloche, K. M. Menten, C. Comito, et al., Astron. Astrophys. 482, 179-196 (2008)

  10. Free collisions in a microgravity many-particle experiment. III. The collision behavior of sub-millimeter-sized dust aggregates

    Science.gov (United States)

    Kothe, Stefan; Blum, Jürgen; Weidling, René; Güttler, Carsten

    2013-07-01

    We conducted micro-gravity experiments to study the outcome of collisions between sub-mm-sized dust agglomerates consisting of μm-sized SiO2 monomer grains at velocities of several cm s-1. Prior to the experiments, we used X-ray computer tomography (nano-CT) imaging to study the internal structure of these dust agglomerates and found no rim compaction so that their collision behavior is not governed by preparation-caused artefacts. We found that collisions between these dust aggregates can lead either to sticking or to bouncing, depending mostly on the impact velocity. While previous collision models derived the transition between both regimes from contact physics, we used the available empirical data from these and earlier experiments to derive a power law relation between dust-aggregate mass and impact velocity for the threshold between the two collision outcomes. In agreement with earlier experiments, we show that the transition between both regimes is not sharp, but follows a shallower power law than predicted by previous models (Güttler, C., Blum, J., Zsom, A., Ormel, C.W., Dullemond, C.P. [2010]. Astron. Astrophys. 513, A56). Furthermore, we find that sticking between dust aggregates can lead to the formation of larger structures. Collisions between aggregates-of-aggregates can lead to growth at higher velocities than homogeneous dust agglomerates.

  11. 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.

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

    Science.gov (United States)

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

    2016-06-01

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

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

    CERN Document Server

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

    2015-01-01

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

  14. 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.

  15. Petrografía y geoquímica de las anfibolitas del cerro La Cocha, Sierra Chica, Córdoba

    Directory of Open Access Journals (Sweden)

    Patricia A Anzil

    2012-06-01

    Full Text Available En la Sierra Chica de Córdoba, a dos kilómetros al sur del Observatorio Astronómico de Bosque Alegre, se encuentran dos variedades litológicas de anfibolitas asociadas al cuerpo ultramáfico de La Cocha. Estas variedades incluyen anfibolitas sin piroxeno, compuestas por hornblenda, plagioclasa, titanita y minerales opacos, emplazadas en el núcleo de la estructura plegada del cuerpo ultramáfico. El segundo grupo son anfibolitas con dos piroxenos, compuestas por hornblenda, plagioclasa, ortopiroxeno (En, clinopiroxeno (Di y como accesorios minerales opacos, apatita, escasa titanita y circón. Estas anfibolitas se encuentran en el encajonante del cuerpo ultramáfico de La Cocha, asociadas a gneises granatíferos sillimaníticos. Con el objetivo de determinar el protolito, que por metamorfismo dieron origen a las anfibolitas, se realizó un estudio geoquímico de roca total. Las anfibolitas con dos piroxenos se clasifican dentro de la serie toleítica y, en base al diagrama de tierras raras se las podría asociar a un ambiente tectónico de generación de tipo N-MORB. Las anfibolitas sin piroxeno, también corresponderían a un ambiente asimilable a N-MORB, con mayor depresión en las tierras raras livianas, sugiriendo probablemente un ambiente de generación del fundido en un manto empobrecido.

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

    International Nuclear Information System (INIS)

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

  17. Dark energy, matter creation and curvature

    International Nuclear Information System (INIS)

    The most studied way to explain the current accelerated expansion of the universe is to assume the existence of dark energy; a new component that fills the universe, does not form clumps, currently dominates the evolution, and has a negative pressure. In this work I study an alternative model proposed by Lima et al. (Abramo and Lima in Class. Quantum Gravity 13:2953, 1996; Zimdahl in Phys. Rev. D 53:5483, 1996; Zimdahl and Pavon in Mon. Not. R. Astron. Soc. 266:872, 1994), which does not need an exotic equation of state, but assumes instead the existence of gravitational particle creation. Because this model fits the supernova observations as well as the ΛCDM model, I perform in this work a thorough study of this model, considering an explicit spatial curvature. I found that in this scenario we can alleviate the cosmic coincidence problem, basically showing that these two components, dark matter and dark energy, are of the same nature, but they act at different scales. I also shown the inadequacy of some particle creation models, and I study a previously proposed new model that overcomes these difficulties. (orig.)

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

    Science.gov (United States)

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

    2010-11-01

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

  19. 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...

  20. 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...

  1. 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.

  2. 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...

  3. 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...

  4. 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.

  5. 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.

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

    Science.gov (United States)

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

    2016-05-01

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

  7. 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.

  8. 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...

  9. 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.

  10. 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.

  11. Búsqueda general con la cámara mosaico CCD del telescopio Schmidt de 1m del Observatorio Nacional de Venezuela

    Directory of Open Access Journals (Sweden)

    I. Ferr\\u00EDn

    2006-01-01

    Full Text Available En el presente trabajo se muestran los resultados del programa de búsqueda y seguimiento de diversos objetos astronómicos: estrellas variables, supernovas y objetos en movimiento dentro del Sistema Solar. Para ello estamos utilizando el telescopio Schmidt de 1m de diámetro del Observatorio Nacional de Venezuela, el cual tiene acoplado una cámara mosaico CCD de 67 Megapíxeles, en un arreglo de 4 x 4 CCDs, cada uno de 2048 x 2048 píxeles. Hasta la presente hemos detectado 372 nuevas estrellas variables, una de las cuales fue identificada como una radiofuente, y el resto son muy probablemente estrellas ráfagas de muy corto periodo. Dentro del Sistema Solar hemos encontrado TNOs (Trans-neptunianos, NEOs (Near-Earths-Objects, cometas y asteroides del cinturón principal. Se diseñó un programa de búsqueda automática para optimizar el procesamiento de los datos. La cámara ya ha demostrado sus grandes posibilidades de observación, siendo sus descubrimientos más representativos 12 nuevos asteroides, 372 estrellas variables y el TNO 38628 Huya.

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

    CERN Document Server

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

    2012-01-01

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

  13. 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...

  14. 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.

  15. Monitoring Light Pollution on the Starlight Reserve of Montsec

    Science.gov (United States)

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

    2015-05-01

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

  16. 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...

  17. 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 ...

  18. Relativistic viscous hydrodynamics for heavy-ion collisions with ECHO-QGP

    Energy Technology Data Exchange (ETDEWEB)

    Del Zanna, L. [Universita di Firenze, Dipartimento di Fisica e Astronomia, Sesto Fiorentino (Italy); INFN, Sezione di Firenze, Sesto Fiorentino (Italy); INAF, Osservatorio Astrofisico di Arcetri, Firenze (Italy); Chandra, V. [INFN, Sezione di Firenze, Sesto Fiorentino (Italy); Inghirami, G. [Universita di Firenze, Dipartimento di Fisica e Astronomia, Sesto Fiorentino (Italy); INFN, Sezione di Firenze, Sesto Fiorentino (Italy); Rolando, V.; Pagliara, G.; Drago, A. [Universita di Ferrara, Dipartimento di Fisica e Scienze della Terra, Ferrara (Italy); INFN, Sezione di Ferrara, Ferrara (Italy); Beraudo, A. [Theory Unit, CERN, Physics Department, Geneve (Switzerland); De Pace, A. [INFN, Sezione di Torino, Torino (Italy); Becattini, F. [Universita di Firenze, Dipartimento di Fisica e Astronomia, Sesto Fiorentino (Italy); INFN, Sezione di Firenze, Sesto Fiorentino (Italy); Frankfurt Institute for Advanced Studies, Frankfurt am Main (Germany)

    2013-08-15

    We present ECHO-QGP, a numerical code for (3+1)-dimensional relativistic viscous hydrodynamics designed for the modeling of the space-time evolution of the matter created in high-energy nuclear collisions. The code has been built on top of the Eulerian Conservative High-Order astrophysical code for general relativistic magneto-hydrodynamics (Del Zanna et al. in Astron. Astrophys. 473:11, 2007) and here it has been upgraded to handle the physics of the Quark-Gluon Plasma. ECHO-QGP features second-order treatment of causal relativistic viscosity effects both in Minkowskian and in Bjorken coordinates; partial or complete chemical equilibrium of hadronic species before kinetic freeze-out; initial conditions based on the Glauber model, including a Monte-Carlo routine for event-by-event fluctuating initial conditions; a freeze-out procedure based on the Cooper-Frye prescription. The code is extensively validated against several test problems and results always appear accurate, as guaranteed by the combination of the conservative (shock-capturing) approach and the high-order methods employed. ECHO-QGP can be extended to include evolution of the electromagnetic fields coupled to the plasma. (orig.)

  19. Formation of water in the interstellar medium

    Science.gov (United States)

    Vidali, Gianfranco; Jing, Dapeng; He, Jiao

    2012-07-01

    The formation of water in the interstellar medium is an important topic of research nowadays because water plays key roles in the cooling of collapsing clouds and, while condensed in ices that cover dust grains, in the formation and storage of molecules of biogenic interest. Furthermore, how water interacts with grains is of importance in understanding the delivery of water to planetary bodies. Water formation occurs largely on dust grains. In the last couple of years, a few laboratories have explored the network of reactions that lead to the formation of water on grain analogs. There are three main branches of this network^1: hydrogenation of O_2, hydrogenation of O_3, and O+H reactions. In our laboratory we studied the formation of water on amorphous silicate films by the interaction of hydrogen and oxygen atoms^2. We will also present measurements of the diffusion of oxygen atoms on amorphous silicate surfaces. Financial support from the NSF Astronomy and Astrophysics Division (grant No. 0908108) is gratefully acknowledged. We like to thank Dr. Brucato and his team (Astrophysical Observatory of Arcetri, Italy) for providing the samples. Tielens, A. G. G. M., & Hagen, W. 1982 ``Model calculations of the molecular composition of interstellar grain mantles'' Astron.& Astrophys., 114, 245. Jing, D., He, J., Brucato, J., De Sio, A., Tozzetti, L. & Vidali, G. 2011 ``On water formation in the interstellar medium: laboratory study of the O+D reaction on surfaces'' Astrophys.J., 741, L9.

  20. Water Formation and Oxygen Chemistry on Dust Grains

    Science.gov (United States)

    Vidali, Gianfranco; He, Jiao

    Water plays an important role in space. As ice on cold dust grains, it provides the medium for a rich chemistry; in the gas-phase, it gives information on the particular environment it is in. It is understood that the formation of water occurs both in the gas-phase and on grains. While the importance of water formation on dust grain surfaces has been recognized for a long time (1) , it is only recently that laboratory investigations have been undertaken to characterize the network of reactions (2) . Closely connected to this work on water formation, is the study of oxygen chemistry on dust grains. Of particular importance is the characterization of the energetics of adsorption, diffusion and desorption of oxygen-containing molecules. I will present data from recent experiments on the interaction of oxygen and hydroxyls with silicate surfaces and on the formation of water on warm (T>30K) amorphous silicates. Such results provide new values to parameters used in simulation codes of the chemical evolution of interstellar space environments. 1. A.G.G.M Tielens & W. Hagen, Astron. & Astrophys. 114, 245 (1982). 2. G. Vidali, J. Low Temp. Phys. 170,1 (2013). This work is supported by the NSF, Astronomy & Astrophysics Division (Grants No. 0908108 and 1311958), and NASA (Grant No. NNX12AF38G). We thank Dr. J.Brucato of the Astrophysical Observatory of Arcetri for providing the samples used in these experiments.

  1. Relativistic viscous hydrodynamics for heavy-ion collisions with ECHO-QGP

    CERN Document Server

    Del Zanna, L; Inghirami, G; Rolando, V; Beraudo, A; De Pace, A; Pagliara, G; Drago, A; Becattini, F

    2013-01-01

    We present ECHO-QGP, a numerical code for $(3+1)$-dimensional relativistic viscous hydrodynamics designed for the modeling of the space-time evolution of the matter created in high energy nuclear collisions. The code has been built on top of the \\emph{Eulerian Conservative High-Order} astrophysical code for general relativistic magneto-hydrodynamics [\\emph{Del Zanna et al., Astron. Astrophys. 473, 11, 2007}] and here it has been upgraded to handle the physics of the Quark-Gluon Plasma. ECHO-QGP features second-order treatment of causal relativistic viscosity effects in both Minkowskian or Bjorken coordinates; partial or complete chemical equilibrium of hadronic species before kinetic freeze-out; initial conditions based on the optical Glauber model, including a Monte-Carlo routine for event-by-event fluctuating initial conditions; a freeze-out procedure based on the Cooper-Frye prescription. The code is extensively validated against several test problems and results always appear accurate, as guaranteed by th...

  2. Axisymmetric equilibrium models for magnetized neutron stars in General Relativity under the Conformally Flat Condition

    CERN Document Server

    Pili, A G; Del Zanna, L

    2014-01-01

    Extremely magnetized neutron stars with magnetic fields as strong as $\\sim 10^{15-16}$ G, or magnetars, have received considerable attention in the last decade due to their identification as a plausible source for Soft Gamma Repeaters and Anomalous X-ray Pulsars. Moreover, this class of compact objects has been proposed as a possible engine capable of powering both Long and Short Gamma-Ray Bursts, if the rotation period in their formation stage is short enough (~1 ms). Such strong fields are expected to induce substantial deformations of the star and thus to produce the emission of gravitational waves. Here we investigate, by means of numerical modeling, axisymmetric static equilibria of polytropic and strongly magnetized stars in full general relativity, within the ideal magneto-hydrodynamic regime. The eXtended Conformally Flat Condition (XCFC) for the metric is assumed, allowing us to employ the techniques introduced for the X-ECHO code [Bucciantini & Del Zanna, 2011, Astron. Astrophys. 528, A101], pro...

  3. Finite axisymmetric charged dust disks in conformastatic spacetimes

    Science.gov (United States)

    González, Guillermo A.; Gutiérrez-Piñeres, Antonio C.; Ospina, Paolo A.

    2008-09-01

    An infinite family of axisymmetric charged dust disks of finite extension is presented. The disks are obtained by solving the vacuum Einstein-Maxwell equations for conformastatic spacetimes, which are characterized by only one metric function. In order to obtain the solutions, a functional relationship between the metric function and the electric potential is assumed. It is also assumed that the metric function is functionally dependent on another auxiliary function, which is taken as a solution of the Laplace equation. The solutions for the auxiliary function are then taken as given by the infinite family of generalized Kalnajs disks recently obtained by González and Reina [G. A. González and J. I. Reina, Mon. Not. R. Astron. Soc. 371, 1873 (2006).MNRAA40035-871110.1111/j.1365-2966.2006.10819.x], expressed in terms of the oblate spheroidal coordinates and corresponding to a family of well-behaved Newtonian axisymmetric thin disks of finite radius. The obtained relativistic thin disks have a charge density that is equal, except maybe by a sign, to their mass density, in such a way that the electric and gravitational forces are in exact balance. The energy density of the disks is everywhere positive and well behaved, vanishing at the edge. Accordingly, as the disks are made of dust, their energy-momentum tensor agrees with all the energy conditions.

  4. Finite axisymmetric charged dust disks in conformastatic spacetimes

    International Nuclear Information System (INIS)

    An infinite family of axisymmetric charged dust disks of finite extension is presented. The disks are obtained by solving the vacuum Einstein-Maxwell equations for conformastatic spacetimes, which are characterized by only one metric function. In order to obtain the solutions, a functional relationship between the metric function and the electric potential is assumed. It is also assumed that the metric function is functionally dependent on another auxiliary function, which is taken as a solution of the Laplace equation. The solutions for the auxiliary function are then taken as given by the infinite family of generalized Kalnajs disks recently obtained by Gonzalez and Reina [G. A. Gonzalez and J. I. Reina, Mon. Not. R. Astron. Soc. 371, 1873 (2006).], expressed in terms of the oblate spheroidal coordinates and corresponding to a family of well-behaved Newtonian axisymmetric thin disks of finite radius. The obtained relativistic thin disks have a charge density that is equal, except maybe by a sign, to their mass density, in such a way that the electric and gravitational forces are in exact balance. The energy density of the disks is everywhere positive and well behaved, vanishing at the edge. Accordingly, as the disks are made of dust, their energy-momentum tensor agrees with all the energy conditions.

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

    CERN Document Server

    Poluianov, Stepan

    2014-01-01

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

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

    Science.gov (United States)

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

    2008-06-01

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

  7. The latest on Apertif

    CERN Document Server

    Oosterloo, Tom; van Cappellen, Wim; (,; Astronomy, Netherlands Institute or Radio; Dwingeloo,; Institute, Kapteyn Astronomical; Groningen,

    2010-01-01

    We describe a Phased Array Feed (PAF) system, called Apertif, which will be installed in the Westerbork Synthesis Radio Telescope (WSRT). The aim of Apertif is, at frequencies from 1.0 to 1.7 GHz, to increase the instantaneous field of view of the WSRT 8 deg^2 and its observing bandwidth to 300 MHz with high spectral resolution. This system will turn the WSRT into an effective survey telescope with scientific applications ranging from deep surveys of the northern sky of HI and OH emission and polarised continuum to efficient searches for pulsars and transients. We present results obtained with a prototype PAF installed in one of the WSRT dishes. These results demonstrate that at decimetre wavelengths PAFs have excellent performance and that even for a single beam on the sky they outperform single feed radio dishes. PAFs turn radio telescopes into very effective survey instruments. Apertif is now fully funded and the community is invited to express their interest in using Apertif (http://www.astron.nl/radio-ob...

  8. 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.

  9. WSO-UV project

    Science.gov (United States)

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

    2014-03-01

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

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

    Science.gov (United States)

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

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

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

    Science.gov (United States)

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

    2014-01-01

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

  12. 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

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

    Science.gov (United States)

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

    2015-12-01

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

  14. 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...

  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. A REDUCE program for the normalization of polynomial Hamiltonians

    Science.gov (United States)

    Ukolov, Yu. A.; Chekanov, N. A.; Gusev, A. A.; Rostovtsev, V. A.; Vinitsky, S. I.; Uwano, Y.

    2005-02-01

    The program LINA01 is proposed for the direct and the inverse normalization of Hamiltonian systems and for the calculation of formal integrals of motion of them. The calculations required in LINA01 are made on the basis of Lie canonical transformation method. The program package of LINA01 is written on REDUCE. Program summaryTitle of program:LINA01 Catalogue identifier:ADUV Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADUV Program obtainable from:CPC Program Library, Queen's University of Belfast, N. Ireland Computer: IBM PC PENTIUM 4/2.40 GHz 512 Mb Operating systems under which the program has been tested: Windows XP Programming language used: REDUCE vs. 3.7 No. of lines in distributed program, including test data, etc.:485 No. of bytes in distributed program, including test data, etc.:4320 Distribution format:tar.gz Nature of physical problem. The transformation bringing a given Hamiltonian function into the normal form (namely, the normalization) is one of the conventional methods for non-linear Hamiltonian systems [A.J. Lichtenberg, M.A. Lieberman, Regular and Stochastic Motion, Springer-Verlag, Berlin, 1983; G.D. Birkhoff, Dynamical Systems, A.M.S. Colloquium Publications, New York, 1927; F. Gustavson, Astron. J. 71 (1966) 670; G.I. Hori, Astron. Soc. Japan 18 (1966) 287; A. Deprit, Cel. Mech. 1 (1969) 12; A.A. Kamel, Cel. Mech. 3 (1970) 90]. Recently, beyond classical mechanics, the normal form method has been applied to quantization of chaotic Hamiltonian systems with the aim of finding quantum signature of chaos [L.E. Reichl, The Transition to Chaos. Conservative Classical Systems: Quantum Manifestations, Springer, New York, 1992]. Besides those utilities, the normalization requires quite cumbersome algebraic calculations of polynomials, so that the computer algebraic approach is worth studying to promote further investigations around the normalization together with the ones around the inverse normalization. Method of solution. The canonical

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

    Science.gov (United States)

    Kuznetsova, Daria; Gritsevich, Maria

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

  18. Mutual Events in the Uranian satellite system in 2007

    Science.gov (United States)

    Arlot, J. E.

    2008-09-01

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

  19. To Mercury dynamics

    Science.gov (United States)

    Barkin, Yu. V.; Ferrandiz, J. M.

    frequencies of free oscillations of core-mantle system of Mercury. Based on the mentioned data about Mercury (Barkin, 1976) we have been obtained the following model values of moments of inertia of the Mercury and for its core:A=0.3499534, B=0.3499667, C=0.35; A_c =B_c =0.1749767, C_c =0.175000 (1quad unit=mR^2, m and R is a mass and a mean radius of the Mercury). Here we used model values for moments of inertia of the core using also some analogy with axysimmetrical model of the core of the Moon from paper Williams et al. (2003). Corresponding periods of free oscillations were determined on the base specially constructed equations of developed theory. They are equal: T_1 =260543\\cdot Trot years and T_2 =0.999468\\cdot Trot (Trot =58.6462 days is a period of Mercury rotation). Last period determines long period of relative oscillation of the core and mantleT_r . The mentioned periods are equal: T_1 =713years and T_r =302years. Barkin's work was accepted by grant SAB2000-0235 of Ministry of Education of Spain and partially by grants AYA2001-0787 and ESP2001-4533 is also aknowledged. References Anderson J.D., Colombo G., Esposito P.B., Lau E.L., Trager G.B.: 1987. The mass, gravity field and ephemeris of Mercury. Icarus, pp. 337-349. Anselmi A., Scoon G.E.N.: 2001. BepiColombo, ESA's Mercury Cornerstone mission. Planetary and Space Science, 49, pp. 1409-1420. Barkin Yu.V.: 1976. About plane periodic motions of a rigid body in gravitational field of a sphere. Astron. J., v. 53, pp. 1110-1119. In Russian. Barkin Yu.V.: 1987. An analytical theory of the lunar rotational motion. Proc. Int. Symp. ``Figure and Dynamics of Earth, Moon and Planets'' (September 1986, Prague). Monograph series of VUGTK. Prague. Pp. 657-677. Beletskij V.V.: 1972. Resonance rotation of celestial bodies and Cassini's laws. Celestial Mechanics, v.6, N3, pp. 356-378. Colombo G.: 1966. Cassini's second and third laws, Astron. J., 71, p. 891. Esposito P.B., Anderson J.D., Ng A.T.Y.: 1977. Experimental

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

    Science.gov (United States)

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

    2006-05-01

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

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

    Science.gov (United States)

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

    2007-09-01

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

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

    Science.gov (United States)

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

    2009-04-01

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

  3. Resonance line radiative transfer for hot atom coronae using Kappa distributions

    International Nuclear Information System (INIS)

    Hot atomic populations are an important component of the planetary exospheres. Usually, radiative transfer models describing the scattering of light by moving atoms assume that these populations have a Maxwellian velocity distribution. However, the velocity distributions of the hot populations could actually have some more extended wings. Popular velocity distributions often used in plasma physics and recently proposed to describe neutral planetary environments are Kappa velocity function distributions. In this paper, following the work of Hummer [Non-coherent scattering: I The redistribution functions with Doppler broadening. R Astron. Soc Month Not 1962;125:21] and Cranmer [Non-Maxwellian redistribution in solar coronal Lyα emission. Astrophys J 1998;508:925-39], we calculate the frequency redistribution functions of radiation scattered by moving atoms with Kappa velocity distribution. We also present a detailed study of a radiative transfer model taking into account Kappa velocity distribution functions, for integer and semi-integer values of κ. We apply this theory to a model of Jupiter hydrogen corona containing 0.1% column density of hot hydrogen to quantify the spectroscopic and imaging differences between Kappa velocity distributions and bi-Maxwellian velocity distributions. When assuming a Kappa velocity distribution with κ=2 for the hot population, intensity increases of ∼40% occur at the bright limb and ∼15% on the disk compared with the same calculations done using a Maxwellian velocity distribution. The line profile differs slightly from a Maxwellian distribution on the disk and at the bright limb, but the difference is larger above the limb. Kappa distributions used to study the Jovian atmosphere are speculative and further studies are needed to link the formation of the hot exospheric populations to the Kappa velocity distributions.

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

    Science.gov (United States)

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

    2015-12-01

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

  5. 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.

  6. 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.

  7. 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

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

    Science.gov (United States)

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

    2016-07-01

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

  9. Black holes in binary stellar systems and galactic nuclei

    Science.gov (United States)

    Cherepashchuk, A. M.

    2014-04-01

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

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

    Science.gov (United States)

    Sosa, Andrea; Fernández, Julio Angel

    2015-08-01

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

  11. 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.

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

    Science.gov (United States)

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

    1997-03-01

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

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

    International Nuclear Information System (INIS)

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

  14. Determination of D/H Ratio on Jupiter from ISO/SWS Observations

    Science.gov (United States)

    Lellouch, E.; Encrenaz, Th.; de Graauw, Th.; Schaeidt, S.; Feuchtgruber, H.; Beintema, D. A.; Bezard, B.; Drossart, P.; Griffin, M.; Heras, A.; Kessler, M.; Leech, K.; Morris, A.; Roelfsema, P. R.; Roos-Serote, M.; Salama, A.; Vandenbussche, B.; Valentijn, E. A.; Davies, G. R.; Naylor, D. A.

    1996-09-01

    Observations of Jupiter, performed on March 29, 1996, with the Short-Wavelength Spectrometer (SWS) of the Infrared Space Observatory (ISO) in Fabry-Perot mode, have allowed the first detection of the rotational R(2) line of HD at 37.7 mu m (265.3 cm(-1) ). The instrument aperture (a rectangular slit of 17" x 40") was approximately aligned with the jovian polar axis and the spectral resolution was about 31000 (FWHM = 0.0012 mu m). The HD line appears as a ~ 10% deep absorption feature at this resolution. We will present an analysis of these observations in terms of the jovian D/H ratio. Complications in the modelling are due to (1) the observing geometry (the aperture encompasses all ranges of airmasses at Jupiter, and Doppler shift effects due to Jupiter's rotation must be accounted for); and (2) possible opacity effects due to the ammonia clouds (synthetic calculations suggest that the continuum is formed near cloud level and Voyager/IRIS spectra indicate significant and latitudinally-varying cloud opacities in the far-infrared range). A preliminary analysis (Encrenaz et al., submitted to Astron. Astrophys.), in which a zero cloud opacity is assumed, shows that the line profile can be satisfactorily fit with a HD/H_2 mixing ratio of 4.4 x 10(-5) (i.e., D/H = 2.2 x 10(-5) ), but adding a cloud opacity will certainly result in an increase of the D/H ratio. A more refined modelling will be presented, and implications of the derived D/H value will be discussed.

  15. Dwarf planet Ceres: Ellipsoid dimensions and rotational pole from Keck and VLT adaptive optics images

    Science.gov (United States)

    Drummond, J. D.; Carry, B.; Merline, W. J.; Dumas, C.; Hammel, H.; Erard, S.; Conrad, A.; Tamblyn, P.; Chapman, C. R.

    2014-07-01

    The dwarf planet (1) Ceres, the largest object between Mars and Jupiter, is the target of the NASA Dawn mission, and we seek a comprehensive description of the spin-axis orientation and dimensions of Ceres in order to support the early science operations at the rendezvous in 2015. We have obtained high-angular resolution images using adaptive optics cameras at the W.M. Keck Observatory and the ESO VLT over ten dates between 2001 and 2010, confirming that the shape of Ceres is well described by an oblate spheroid. We derive equatorial and polar diameters of 967 ± 10 km and 892 ± 10 km, respectively, for a model that includes fading of brightness towards the terminator, presumably linked to limb darkening. These dimensions lie between values derived from a previous analysis of a subset of these images obtained at Keck by Carry et al. (Carry et al. [2008]. Astron. Astrophys. 478 (4), 235-244) and a study of Hubble Space Telescope observations (Thomas et al. [2005]. Nature 437, 224-226). Although the dimensions are 1-2% smaller than those found from the HST, the oblateness is similar. We find the spin-vector coordinates of Ceres to lie at (287°, +64°) in equatorial EQJ2000 reference frame (346°, +82° in ecliptic ECJ2000 coordinates), yielding a small obliquity of 3°. While this is in agreement with the aforementioned studies, we have improved the accuracy of the pole determination, which we set at a 3° radius.

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

    Science.gov (United States)

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

    2015-11-01

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

  17. SCUBA-2: A large-format TES array for submillimetre astronomy

    International Nuclear Information System (INIS)

    SCUBA-2, which replaces the Submillimetre Common User Bolometer Array (SCUBA) (Mon. Not. R. Astron. Soc. 303 (1999) 659) on the James Clerk Maxwell telescope in 2006, will be the first CCD-like array for submillimeter astronomy. Unlike previous detectors which have used discrete bolometers, SCUBA-2 has two DC-coupled, monolithic, filled arrays with a total of ∼10,000 bolometers. It will offer simultaneous imaging of an 8x8 arcmin field of view at wavelengths of 850 and 450 μm. SCUBA-2 is expected to have a huge impact on the study of galaxy formation and evolution in the early Universe as well as star and planet formation in our own Galaxy. Mapping the sky to the same S/N up to 1000 times faster than SCUBA, it will also act as a pathfinder for the new submillimetre interferometers such as ALMA. SCUBA-2's absorber-coupled pixels use superconducting transition edge sensors (Ph.D. Thesis, Stanford, 1995) operating at ∼120 mK for photon noise limited performance. The monolithic silicon detector arrays are deep-etched by the Bosch process to isolate the pixels on silicon nitride membranes (Nucl. Instr. and Meth. A, these proceedings). Electrical connections are made through indium bump bonds to a backplane that incorporates a SQUID time-domain multiplexer. We describe the key technologies that make SCUBA-2 possible and give an update on the considerable progress in the detector development and instrument design that has taken place over the last 2 years

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

    Science.gov (United States)

    Bodri, L.; Čermák, V.

    1998-06-01

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

  19. 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.

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

    Science.gov (United States)

    Blackman, Eric G.; Nauman, Farrukh

    2015-10-01

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

  1. Situação da Mulher na Astronomia Brasileira

    Science.gov (United States)

    Silva, Adriana V. R.

    2007-07-01

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

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

    Institute of Scientific and Technical Information of China (English)

    万映秋; 唐泉

    2014-01-01

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

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

    Science.gov (United States)

    Tennyson, Jonathan

    2013-06-01

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

  4. 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.

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

    Science.gov (United States)

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

    2012-09-01

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

  6. 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.

  7. THE BREAKDOWN OF CLASSICAL GRAVITY?

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    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.

  8. High Resolution Measurements and Electronic Structure Calculations of a Diazanaphthalene

    Science.gov (United States)

    Gruet, Sébastien; Goubet, Manuel; Pirali, Olivier

    2014-06-01

    Polycyclic Aromatic Hydrocarbons (PAHs) have long been suspected to be the carriers of so called Unidentified Infrared Bands (UIBs). Most of the results published in the literature report rotationally unresolved spectra of pure carbon as well as heteroatom-containing PAHs species. To date for this class of molecules, the principal source of rotational informations is ruled by microwave (MW) spectroscopy while high resolution measurements reporting rotational structure of the infrared (IR) vibrational bands are very scarce. Recently, some high resolution techniques provided interesting new results to rotationally resolve the IR and far-IR bands of these large carbonated molecules of astrophysical interest. One of them is to use the bright synchrotron radiation as IR continuum source of a high resolution Fourier transform (FTIR) spectrometer. We report the very complementary analysis of the [1,6] naphthyridine (a N-bearing PAH) for which we recorded the microwave spectrum at the PhLAM laboratory (Lille) and the high resolution far-infrared spectrum on the AILES beamline at synchrotron facility SOLEIL. MW spectroscopy provided highly accurate rotational constants in the ground state to perform Ground State Combinations Differences (GSCD) allowing the analysis of the two most intense FT-FIR bands in the 50-900 wn range. Moreover, during this presentation the negative value of the inertial defect in the GS of the molecule will be discussed. A. Leger, J. L. Puget, Astron. Astrophys. 137, L5-L8 (1984) L. J. Allamandola et al. Astrophys. J. 290, L25-L28 (1985). Z. Kisiel et al. J. Mol. Spectrosc. 217, 115 (2003) S. Thorwirth et al. Astrophys. J. 662, 1309 (2007) D. McNaughton et al. J. Chem. Phys. 124, 154305 (2011). S. Albert et al. Faraday Discuss. 150, 71-99 (2011) B. E. Brumfield et al. Phys. Chem. Lett. 3, 1985-1988 (2012) O. Pirali et al. Phys. Chem. Chem. Phys. 15, 10141 (2013).

  9. 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.

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

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    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.

  11. 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.

  12. On 17 22 January 2005 Events in Space Weather

    Science.gov (United States)

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

    2008-08-01

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

  13. Neptunian Satellites observed with Keck AO system

    Science.gov (United States)

    Marchis, F.; Urata, R.; de Pater, I.; Gibbard, S.; Hammel, H. B.; Berthier, J.

    2004-05-01

    The Neptunian system was observed on 9 different nights between July 2002 and October 2003 with the 10-m Keck telescope on Mauna Kea, Hawaii, and its facility instrument NIRC2 coupled with the Adaptive Optics system. Data were recorded in J (1.2μ m), and H (2.2μ m) bands. The angular resolution achieved on a one-minute integration time image is 0.50 arcsec, corresponding to a spatial resolution of 1100 km. The images display small structures such as the rings (de Pater et al. 2004), clouds in the atmosphere (Gibbard et al. 2003), and inner satellites, mainly Proteus, Larissa, Galatea, Despina, and Thalassa. On the 40 images, the positions and intensities of the satellites detected were accurately measured fitting the signal with a gaussian profile. The center of Neptune was obtained by fitting the disk position with an ellipse. After correcting for the detector distortion, we compared the satellite positions with the predicted ones delivered by several ephemerides. We used the JPL (NEP016 + NEP022 + DE405) and two IMCCE ephemerides, an old version (VSOP87+Owen et al., 1991) and a more recent one (DE405+Le Guyader et al., 1993). All cases, we confirmed the presence of an apparent shift between the predicted and the observed positions. Table 1 (see http://astron.berkeley.edu/ fmarchis/Science/Neptune/Satellites/) summarizes the mean distance of the shift for satellites most frequently observed and the various ephemerides. In this presentation, we will report the positions of the satellites, and present their color and possible photometric variations derived from the observations. This work has been partially supported by the National Science Foundation Science and Technology Center for Adaptive Optics, managed by the University of California at Santa Cruz under cooperative agreement No. AST - 9876783.

  14. A New Model for the Seasonal Evolution of Triton

    Science.gov (United States)

    Forget, F.; Decamp, N.; Berthier, J.; Le Guyader, C.

    2000-10-01

    The seasonal evolution of Triton's surface and atmosphere remains poorly understood. No model [1] has been able to fully reproduce the main characterictics of the Voyager 2 observations in 1989 in combination with the "Global warming" recently inferred from stellar occultations [2]. Within this context, we have developped a new thermal model to study the seasonal nitrogen cycle on Triton. The model is the surface part of a Triton atmosphere General circulation model developped at LMD [3]. The nitrogen cycle was found to be very sensitive to Triton complex seasonal variations of the subsolar point latitude, especially during the current decade (south summer solstice). Since only pre-Voyager formulations were available for such a study, this has motivated some new calculations of Triton's motion based on more recent rotationnal elements combined with a relatively complete dynamic solution [4] adapted to Triton. A new analytic formulation suitable for climate modelling has been derived. On this basis, we wish to suggest a new, realistic scenario to explain Triton's apparence and evolution based on solar-induced variation of the frost albedo. Such variations have been observed in Mars CO2 ice seasonal polar caps [5]. Although they seem to result from complex microphysical behavior, they are likely to occur on Triton since both Triton and Mars polar caps are composed of weakly absorbing ice (N2 or CO2) in vapor pressure equilibrium with the main constituant of the atmosphere. [1] e.g. Hansen and Paige, Icarus 99, 273-288 (1992); Brown and Kirk, J. Geophys. Res. 99, 1965-1981 (1994); Spencer and Moore, Icarus 99, 261-272 (1992). [2] Elliot et al., Nature 393, 765-767 (1998). [3] Forget, Descamp and Hourdin, in ``Pluto and Triton, comparisons and evolution over time", Lowell Observatory's fourth annual workshop, Flagstaff, Arizona. (1999) [4] Le Guyader, Astron. Astrophys. 272, 687-694 (1993). [5] Kieffer et al., J. Geophys. Res. 105, 9653-9700 (2000).

  15. 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.

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

    Science.gov (United States)

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

    2014-01-01

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

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

    Science.gov (United States)

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

    2007-01-01

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

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

    Science.gov (United States)

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

    2007-01-01

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

  19. Cartography intended to data gravimetric representation Cartografia destinada à representação de dados gravimétricos

    Directory of Open Access Journals (Sweden)

    Vivian de Oliveira Fernandes

    2013-06-01

    Full Text Available This work will be exposed to the application of thematic mapping techniques for proper representation of the gravity data, through explanation of the application isolines maps. The data used for this study are part of a database gravity from the Institute of Astronomy and Geophysics (IAG and Companhia Paranaense de Energia Eletrica (Copel Paraná, totaling approximately 9000 stations, among these geodetic data, gravity and topography. In the mapping process, first evaluated phenomenon classification in question to define the vertical intervals and points distribution analysis. Later interpolation was performed with the aid of the isolines Surfer and the representation of the final gravimetric map for the Curitiba city.Neste trabalho será exposta a aplicação de técnicas de cartografia temática para a adequada representação de dados gravimétricos, através da explanação da aplicação do mapeamento de isolinhas. Os dados utilizados para este estudo fazem parte de um banco de dados gravimétricos provenientes do Instituto Astronômico e Geofísico (IAG e Companhia Paranaense de Energia Elétrica (COPEL do Paraná, totalizando aproximadamente 9000 estações, entre estes dados geodésicos, gravimétricos e topográficos. No processo de mapeamento, primeiramente foi avaliada a classificação do fenômeno em questão para definição dos intervalos verticais e análise da distribuição dos pontos. Posteriormente foi realizada a interpolação das isolinhas com auxílio do programa Surfer e a representação final do mapa gravimétrico para o município de Curitiba.

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

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    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.

  1. Analysis of selected Kepler Mission planetary light curves

    Science.gov (United States)

    Rhodes, M. D.; Budding, E.

    2014-06-01

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

  2. 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)

  3. 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).

  4. 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.

  5. 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.

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

    Science.gov (United States)

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

    1997-05-01

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

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

    Science.gov (United States)

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

    2011-12-01

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

  8. A New Interstellar Cyclic Molecule, Ethylene Oxide

    Science.gov (United States)

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

    1997-12-01

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

  9. Radioastron studies of the nearby, turbulent interstellar plasma with the longest space-ground interferometer baseline

    Energy Technology Data Exchange (ETDEWEB)

    Smirnova, T. V.; Shishov, V. I. [Pushchino Radio Astronomy Observatory, Astro Space Center, Lebedev Physical Institute, Russian Academy of Sciences, Pushchino, Moscow Oblast' 142290 (Russian Federation); Popov, M. V.; Andrianov, A. S.; Kardashev, N. S.; Kovalev, Y. Y.; Soglasnov, V. A.; Zhuravlev, V. I. [Astro Space Center, Lebedev Physical Institute, Russian Academy of Sciences, Profsoyuznaya str.84/32, Moscow 117997 (Russian Federation); Gwinn, C. R.; Johnson, M. D. [Department of Physics, University of California, Santa Barbara, CA 93106 (United States); Anderson, J. M.; Karuppusamy, R.; Kramer, M.; Zensus, J. A. [Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn (Germany); Bartel, N. [York University, Department of Physics and Astronomy, 4700 Keele Street, Toronto, Ontario M3J 1P3 (Canada); Deller, A. [The Netherlands Institute for Radio Astronomy (ASTRON), Dwingeloo (Netherlands); Joshi, B. C., E-mail: zhur@asc.rssi.ru [National Centre for Radio Astrophysics, Post Bag 3, Ganeshkhind, Pune 411007 (India)

    2014-05-10

    RadioAstron space-ground very long baseline interferometry observations of the pulsar B0950+08, conducted with the 10 m Space Radio Telescope in conjunction with the Arecibo 300 m telescope and the 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 θ{sub 0} = 1.1-4.4 mas, with the refraction direction being approximately perpendicular to the observer velocity. We show that the observed parameters of scintillation effects indicate that two plasma layers lie along the line of sight to the pulsar, at distances of 4.4-16.4 pc and 26-170 pc, and traveling in different directions relative to the line of sight. Spectra of turbulence for the two layers are found to follow a power law with the indices γ{sub 1} = γ{sub 2} = 3.00 ± 0.08, significantly different from the index expected for a Kolmogorov spectrum of turbulence, γ = 11/3.

  10. Radioastron studies of the nearby, turbulent interstellar plasma with the longest space-ground interferometer baseline

    International Nuclear Information System (INIS)

    RadioAstron space-ground very long baseline interferometry observations of the pulsar B0950+08, conducted with the 10 m Space Radio Telescope in conjunction with the Arecibo 300 m telescope and the 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 θ0 = 1.1-4.4 mas, with the refraction direction being approximately perpendicular to the observer velocity. We show that the observed parameters of scintillation effects indicate that two plasma layers lie along the line of sight to the pulsar, at distances of 4.4-16.4 pc and 26-170 pc, and traveling in different directions relative to the line of sight. Spectra of turbulence for the two layers are found to follow a power law with the indices γ1 = γ2 = 3.00 ± 0.08, significantly different from the index expected for a Kolmogorov spectrum of turbulence, γ = 11/3.

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

    Science.gov (United States)

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

    2016-01-01

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

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

    Science.gov (United States)

    Correia, Alexandre C. M.; Laskar, Jacques

    2009-05-01

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

  13. 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

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

    Science.gov (United States)

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

    2011-11-01

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

  15. 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.

  16. 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.

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

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    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.

  18. Estimación espectral de datos ambientales no equiespaciados vía el periodograma suavizado de Lomb-Scargle. Una breve revisión

    Directory of Open Access Journals (Sweden)

    Josué M. Polanco-Martínez

    2014-12-01

    Full Text Available El periodograma suavizado de Lomb-Scargle es una técnica de análisis espectral que se aplica de modo directo a series temporales no equiespaciadas. Aunque derivado originalmente para operar con series temporales astronómicas no equiespaciadas temporalmente [2, 17, 38, 39], a finales de los noventa fue adaptado por Schulz y Stattegger [43] en combinación con la técnica WOSA (Welch-Overlapped-Segment-Averaging [49] para operar con series temporales ambientales (principalmente climáticas no equiespacidas temporalmente. Un poco más tarde, Schulz y Mudelsee [42] hicieron mejoras al trabajo de Schulz y Stattegger para tener en cuenta el tipo de ruido de fondo (“rojo” que suelen presentar las series ambientales. Debido a la necesidad de estimar el espectro suavizado a series temporales ambientales no equiespaciadas temporalmente, es necesario contar con información suficiente y de libre acceso sobre esta temática. Hoy por hoy, es posible encontrar una buena cantidad de publicaciones en inglés sobre este método (v. gr., [23, 24, 28, 29, 42, 43], pero hay una carencia de información en idioma español (salvo algunas excepciones, como Polanco-Martínez [31] y Pardo-Igúzquiza y Rodríguez-Tovar [27]. Por estas razones, en este artículo de revisión, se presenta de manera concisa toda la información pertinente para estimar el espectro suavizado de series temporales ambientales no equiespaciadas, mediante el periodograma de Lomb-Scargle y teniendo en cuenta el ruido de fondo rojo de las series ambientales.

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

    Science.gov (United States)

    Sepehri, Alireza; Pradhan, Anirudh; Shoorvazi, Somayyeh

    2016-02-01

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

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

    Science.gov (United States)

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

    2014-11-01

    We present a series of numerical integrations of observed and fictitious Jupiter Trojan asteroids, under the gravitational effects of the four outer planets, for time-spans comparable with the age of the Solar System. From these results we calculate the escape rate from each Lagrange point, and construct dynamical maps of "permanence" time in different regions of the phase space. Fictitious asteroids in L4 and L5 show no significant difference, showing almost identical dynamical maps and escape rates. For real Trojans, however, we found that approximately 23% of the members of the leading swarm escaped after 4.5 Gyrs, while this number increased to 28.3% for L5 . This implies that the asymmetry between the two populations increases with time, indicating that it may have been smaller at the time of formation/capture of these asteroids. Nevertheless, the difference in chaotic diffusion cannot, in itself, account for the current observed asymmetry (∼40%), and must be primarily primordial and characteristic of the capture mechanism of the Trojans. Finally, we calculate new proper elements for all the numbered Trojans using the semi-analytical approach of Beaugé and Roig (Beaugé, C., Roig, F.V. [2001]. Icarus, 153, 391-415), and compare the results with the numerical estimations by Brož and Rosehnal (Brož, M., Rosehnal, J. [2011]. Mon. Not. R. Astron. Soc. 414, 565-574). For asteroids that were already numbered in 2011, both methods yield very similar results, while significant differences were found for those bodies that became numbered after 2011.

  1. 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

  2. Evolution of the Astronomy Concepts Along Basic Education Cycle. (Breton Title: Evolução dos Conceitos de Astronomia no Decorrer da Educação Básica.) La Evolución de los Conceptos de Astronomía Durante la Educación Básica

    Science.gov (United States)

    Darroz, Luiz Marcelo; da Rosa, Cleci Werner; Becker da Rosa, Álvaro; Samudio Pèrez, Carlos Ariel

    2014-07-01

    learning of astronomy in basic education. Embora a astronomia seja considerada uma das ciências mais antigas da humanidade e ainda que a compreensão de seus conceitos tenha trazido enormes avanços para a Ciência e, consequentemente, para a sociedade, observa-se que uma parcela significativa de pessoas encontra-se à margem desses conhecimentos. De acordo com os Parâmetros Curriculares Nacionais para a Educação Básica, cabe à escola a difusão dos conceitos cientificamente corretos, entre eles os relacionados à área de astronomia. Pertinente a essa questão, apresenta-se uma pesquisa realizada com 140 estudantes do nono ano do ensino fundamental e com 120 estudantes da terceira série do ensino médio de quatro escolas da região de Passo Fundo/RS. Buscou-se averiguar, por meio de um questionário composto de questões abertas e de múltipla escolha, o conhecimento desse grupo de estudantes acerca de termos e fenômenos astronômicos básicos e, também, verificar se o índice de acertos cresce à medida que eles avançam nas diferentes e gradativas séries dos ensinos fundamental e médio. De modo geral, os resultados apresentados demonstram que o ensino de astronomia na educação básica enfrenta deficiências. Das 20 questões investigadas, em 17 os índices de acertos são semelhantes nas respostas dadas por estudantes de nível fundamental e médio, revelando que muitas concepções equivocadas permanecem ao longo da educação básica. Isso evidencia que tais temas não são - ou são pouco - abordados durante esses dois níveis de escolarização. Assim, conclui-se que a discussão dos conceitos relacionados com a astronomia deve receber maior ênfase na abordagem dos diferentes conteúdos, sendo necessária uma ação nacional em prol do seu ensino. Acredita-se que essa ação nacional deve estar apoiada em um pilar triplo de atores coletivos: comunidade científica, comunidade astronômica semiprofissional e comunidade escolar. Por fim, esse pilar seria

  3. Accurate PSF-matched photometry for the J-PAS survey

    Science.gov (United States)

    Jimenez-Teja, Yolanda; Benitez, Txitxo; Dupke, Renato a.

    2015-08-01

    & Arnouts 1996, Astron Astrophys Sup, 117, 393) and ColorPro (Coe et al. 2006, AJ, 132, 926), using real data from the COSMOS survey, the HUDF, and the XDF.

  4. R&D at JIVE: transforming the way VLBI is done

    Science.gov (United States)

    Szomoru, Arpad; van Langevelde, Huib

    2015-08-01

    Arpad Szomoru, Huib van Langevelde and the JIVE staffFor many years, the heart of operations at JIVE has been the MkIV hardware correlator, a custom-built high-performance data processor. At this time the MkIV has been replaced by the locally developed EVN software correlator (SFXC).This development has vastly improved the science capacity of the EVN, by providing higher spectral resolution and polarization accuracy, but most notably, by enabling completely new observing modes. Observing multiple simultaneous field centers has enabled wide-field imaging, while a phased-array mode has made it possible to do pulsar time series with the EVN. New algorithms have been developed for near-field VLBI, making it possible to focus on objects within our solar system. This has been used to track the RadioAstron satellite, and by applying the derived orbital parameters to improve subsequent space VLBI observations.New digital baseband convertors will allow higher observing bandwidths in the EVN. In anticipation of this, and of the even higher bandwidths of future mm-VLBI observations, added to the deployment of much larger arrays (including the AVN, the SKA precursors and the SKA itself), we are investigating more powerful and economical solutions. The JIVE UniBoard Correlator is the first FPGA-based EVN correlator; its scalability and flexibility are now under assessment. The new UniBoard2 project, also sponsored by the EC, will skip two generations of FPGA technology and deliver enormous processing power at lower power consumption.Maybe just as importantly, research is ongoing into software tools to enable the efficient handling of the vast data sets that the EVN and other current and future instruments will produce. New data processing pipelines are being designed that will be able to cache intermediate products, and upon changing parameters only re-calculate what is needed, as opposed to re-starting every time from scratch.Finally, we will discuss the development of time

  5. Ionized gas diagnostics from protoplanetary discs in the Orion nebula and the abundance discrepancy problem

    Science.gov (United States)

    Mesa-Delgado, A.; Núñez-Díaz, M.; Esteban, C.; García-Rojas, J.; Flores-Fajardo, N.; López-Martín, L.; Tsamis, Y. G.; Henney, W. J.

    2012-10-01

    for the intrinsic spectra of 177-341, while the background emission presents the typical ADF(O2 +) observed in the Orion nebula (0.16 ± 0.11 dex). We conclude that the presence of high-density ionized gas is severely affecting the abundances determined from CELs and, therefore, those from RLs should be considered as a better approximation to the true abundances. Based on observations collected at the Centro Astronómico Hispano Alemán (CAHA) at Calar Alto, operated jointly by the Max-Planck Institut für Astronomie and the Instituto de Astrofísica de Andalucía (CSIC).

  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. A new method to find the potential center of N-Body systems

    Directory of Open Access Journals (Sweden)

    F. Cruz

    2002-01-01

    Full Text Available Se presenta un método rápido para encontrar el centro del potencial de una distribución de N-cuerpos. El método usa un algoritmo iterativo que aprovecha el hecho de que el gradiente del potencial es nulo en su centro; emplea asimismo un radio de suavizado para evitar quedar atrapado en mínimos locales. Se ha probado el método con modelos de King (cuyos núcleos, de densidad relativamente constante, hacen particularmente difícil la determinación numérica de este centro, y se ha comparado su eficiencia y precisión con un método más directo, aunque de cálculo intensivo, basado en mallas cartesianas de resolución espacial creciente. En todos los casos, ambos métodos convergen al mismo centro dentro de la resolución de la malla, aunque el método iterativo es dos _ordenes de magnitud más rápido. Utilizamos este método en un problema astronómico: la evolución de un modelo de King de 105 partículas, en orbita alrededor de un potencial fijo representativo de nuestra Galaxia. Se utilizó un código de N-cuerpos con expansión en armónicos esféricos, en el que la determinación del centro del potencial es esencial para un cálculo correcto de las fuerzas. Se comparó esta simulación con el mismo código pero con un método empleado anteriormente para determinar el centro de expansión (White 1983. Con nuestra rutina se obtienen mejores resultados en la conservación de energía y de la masa.

  8. Evaluación de la escala Borg de esfuerzo percibido aplicada a la rehabilitación cardiaca Instrument evaluation of Borg's perceived exertion scale in cardiac rehabilitation

    Directory of Open Access Journals (Sweden)

    Natalie Burkhalter

    1996-12-01

    Full Text Available La escala Borg de esfuerzo percibido mide la gama entera del esfuerzo que el individuo percibe al hacer ejercicio. Esta escala da criterios para hacerle ajustes a la intensidad de ejercicio, o sea, a la carga de trabajo, y así pronosticar y dictaminar las diferentes intensidades del ejercicio en los deportes y en la rehabilitación médica (BORG, 1982. También se puede usar tanto en el atletismo, en la astronáutica, la industria y ambientes militares, como en las situaciones cotidianas. El concepto del esfuerzo percibido es una valoración subjetiva que indica la opinión del sujeto respecto a la intensidad del trabajo realizado (MORGAN, 1973. El sujeto que hace el ejercicio debe asignar un número del 1 al 20, para representar la sensación subjetiva de la cantidad de trabajo desempeñado. La escala es una herramienta valiosa dentro del ámbito del desempeño humano, en que a menudo la consideración importante no es tanto "lo que haga el individuo" "sino" "lo que cree que hace" (MORGAN, 1973.Borg's perceived exertion scale measures the extent of perceived exertion which a person experiences during exercise. The perceived exertion scale is used to adjust exercise intensity (workload for predictions and prescriptions of exercise intensities in sports and medical rehabilitation (BORG, 1982. In addition, Borg's scale can be used in the athletic arena, space, industry, military settings, or under everyday circumstances. The concept of perceived exertion is a subjective rating, indicating the subject's opinion about the intensity of the work being performed (MORGAN, 1973. The task of exercising subjects is to assign a number (from 1-20 to represent the subjective sensation of the amount of work being performed. This is a valuable tool in human performance setting, where an important consideration is not "what the individual is doing, but what he thinks and is doing" (MORGAN, 1973.

  9. Usina de ciências: um espaço pedagógico para aprendizagens múltiplas

    Science.gov (United States)

    Martin, V. A. F.; Poppe, P. C. R.; Orrico, A. C. P.; Pereira, M. G.

    2003-08-01

    Entendemos que o Ensino de Astronomia é especialmente apropriado para motivar os alunos e aprofundar conteúdos em diversas áreas do conhecimento, pois envolve temas ligados à Física, Matemática, Química, Computação, Tratamento de Imagens e Instrumentação de Alta Precisão, além daqueles pertinentes as áreas de Geografia, História e Antropologia. Contudo, apesar do caráter interdisciplinar que esta ciência possui, a realidade atual é que a maioria dos professores em sala de aula não foram devidamente capacitados, durante o período de formação acadêmica, para ministrar conteúdos de Astronomia nos atuais Ensinos Fundamental e Médio. Neste trabalho, discutiremos de maneira ampla, num primeiro momento, a realidade do atual ensino de ciências praticado no Estado da Bahia, apontando por dependência administrativa, o crescimento e a redução do número de escolas, da taxa de analfabetismo por faixa etária, da escolarização, do atendimento, da aprovação, reprovação e abandono, de equipamentos e laboratórios e o grau de formação dos nossos atuais professores em pleno exercício de atividade docente. Num segundo momento, discutiremos o papel do Observatório Astronômico Antares/UEFS dentro desse contexto, ou seja, suas ações implementadas ao longo dos últimos anos e em particular, o recente projeto de extensão Ensino e Difusão de Astronomia, financiado pela Fundação Vitae, que procura traduzir no lúdico, no brincar de ciências, um espaço pedagógico para aprendizagens múltiplas. Neste, o papel do professor multiplicador associado ao laboratório de kits didáticos, de fácil construção e manipulação (alguns dos quais serão mostrados), perfazem os principais veículos para o desenvolvimento de conhecimentos, atitudes, habilidades e valores que preparam os nossos alunos para a carreira técnico-científica e para sua participação crítica e criativa na Sociedade.

  10. Simulation of an X-ray CdTe:Cl detector in counting mode at high flows for radiography and tomography

    International Nuclear Information System (INIS)

    The use of a semiconductor detector CdTe:Cl for a counting measure of a strong X-photon flux is possible. However, for flows in excess of one hundred million photons per second per square millimeter, we observe a temporal instability in the measures because of the appearance of a space charge in the material. Moreover, this space charge also has an impact on the shape of the 20 image count by changing the curvature of the field lines. The work of this thesis focused on the simulation of the measurement chain, from the Interaction of the photon radiation field X in the semiconductor to the response of the counting electronics. For this, the main obstacle has been the dynamic modeling of space charge and we concentrated our efforts on this particular point. lt is apparent that the precise knowledge of trap levels in the detector was unthinkable. So to overcome this difficulty, rather than modeling the electric field, we have measured it by Pockels effect. For this. we developed an experimental bench capable of measuring a dynamic electrical field in a detector during astron X-rays irradiation. In addition, we have coupled the measure of field at the counting measure to allow us to connect the two. We validated our simulation of the acquisition of three points: the electric field, the signals due to the interaction of X-rays and measured at the electrodes and the counting response. Thus, our work has resulted in the development and the validation of two tools, useful for understanding the phenomena related to the appearance of a space charge. The first tool is our bench measuring electric field Pockels effect. It allows us to know the amplitude of the field at any point at any moment. And the second tool is our complete simulation of a CdTe detector Cl in counting mode with high flows, ranging from the interaction radiation-matter to the response count. We were able to show that space charge is the origin of temporal and spatial instabilities of the measure count

  11. 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)

  12. Developing the Planetary Science Virtual Observatory

    Science.gov (United States)

    Erard, Stéphane; Cecconi, Baptiste; Le Sidaner, Pierre; Henry, Florence; Chauvin, Cyril; Berthier, Jérôme; André, Nicolas; Génot, Vincent; Schmitt, Bernard; Capria, Teresa; Chanteur, Gérard

    2015-08-01

    In the frame of the Europlanet-RI program, a prototype Virtual Observatory dedicated to Planetary Science has been set up. Most of the activity was dedicated to the definition of standards to handle data in this field. The aim was to facilitate searches in big archives as well as sparse databases, to make on-line data access and visualization possible, and to allow small data providers to make their data available in an interoperable environment with minimum effort. This system makes intensive use of studies and developments led in Astronomy (IVOA), Solar Science (HELIO), and space archive services (IPDA).The current architecture connects existing data services with IVOA or IPDA protocols whenever relevant. However, a more general standard has been devised to handle the specific complexity of Planetary Science, e.g. in terms of measurement types and coordinate frames. This protocol, named EPN-TAP, is based on TAP and includes precise requirements to describe the contents of a data service (Erard et al Astron & Comp 2014). A light framework (DaCHS/GAVO) and a procedure have been identified to install small data services, and several hands-on sessions have been organized already. The data services are declared in standard IVOA registries. Support to new data services in Europe will be provided during the proposed Europlanet H2020 program, with a focus on planetary mission support (Rosetta, Cassini…).A specific client (VESPA) has been developed at VO-Paris (http://vespa.obspm.fr). It is able to use all the mandatory parameters in EPN-TAP, plus extra parameters from individual services. A resolver for target names is also available. Selected data can be sent to VO visualization tools such as TOPCAT or Aladin though the SAMP protocol.Future steps will include the development of a connection between the VO world and GIS tools, and integration of heliophysics, planetary plasma and reference spectroscopic data.The EuroPlaNet-RI project was funded by the European

  13. Models of dark matter halos based on statistical mechanics: The fermionic King model

    Science.gov (United States)

    Chavanis, Pierre-Henri; Lemou, Mohammed; Méhats, Florian

    2015-12-01

    We discuss the nature of phase transitions in the fermionic King model which describes tidally truncated quantum self-gravitating systems. This distribution function takes into account the escape of high-energy particles and has a finite mass. On the other hand, the Pauli exclusion principle puts an upper bound on the phase-space density of the system and stabilizes it against gravitational collapse. As a result, there exists a statistical equilibrium state for all accessible values of energy and temperature. We plot the caloric curves and investigate the nature of phase transitions as a function of the degeneracy parameter in both microcanonical and canonical ensembles, extending the work of Chavanis [Int. J. Mod. Phys. B 20, 3113 (2006)] for box-confined configurations. We consider stable and metastable states and emphasize the importance of the latter for systems with long-range interactions. Phase transitions can take place between a "gaseous" phase unaffected by quantum mechanics and a "condensed" phase dominated by quantum mechanics. The phase diagram exhibits two critical points, one in each ensemble, beyond which the phase transitions disappear. There also exists a region of negative specific heats and a situation of ensemble inequivalence for sufficiently large systems. In the microcanonical ensemble, gravitational collapse (gravothermal catastrophe) results in the formation of a small degenerate object containing a small mass. This is accompanied by the expulsion of a hot envelope containing a large mass. In the canonical ensemble, gravitational collapse (isothermal collapse) leads to a small degenerate object containing almost all the mass. It is surrounded by a tenuous envelope. We apply the fermionic King model to the case of dark matter halos made of massive neutrinos following the work of de Vega, Salucci, and Sanchez [Mon. Not. R. Astron. Soc. 442, 2717 (2014)]. The gaseous phase describes large halos and the condensed phase describes dwarf halos

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

    Science.gov (United States)

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

    2016-01-01

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

  15. Quantum Chemical Evaluation of the Astrochemical Significance of Reactions between S Atom and Acetylene or Ethylene

    Science.gov (United States)

    Woon, David E.

    2007-01-01

    Addition-elimination reactions of S atom in its P-3 ground state with acetylene (C2H2) and ethylene (C2H4) were characterized with both molecular orbital and density functional theory calculations employing correlation consistent basis sets in order to assess the likelihood either reaction might play a general role in astrochemistry or a specific role in the formation of S2 (X (sup 3 SIGMA (sub g) (sup -)) via a mechanism proposed by Saxena and Misra (Mon. Not. R. Astron. Soc. 1995, 272, 89). The acetylene and ethylene reactions proceed through C2H2S ((sup 3)A")) and C2H4S ((sup 3)A")) intermediates, respectively, to yield HCCS ((sup 2)II)) and C2H3S ((sup 2)A')). Substantial barriers were found in the exit channels for every combination of method and basis set considered in this work, which effectively precludes hydrogen elimination pathways for both S + C2H2 and S + C2H4 in the ultracold interstellar medium where only very modest barriers can be surmounted and processes without barriers tend to predominate. However, if one or both intermediates is formed and stabilized efficiently under cometary or dense interstellar cloud conditions, they could serve as temporary reservoirs for S atom and participate in reactions such as S + C2H2S (right arrow) S2 = C2H2 or S + C2H4S (right arrow) S2 + C2H4. For formation and stabilization to be efficient, the reaction must possess a barrier height small enough to be surmountable at low temperatures yet large enough to prevent redissociation to reactants. Barrier heights computed with B3LYP and large basis sets are very low, but more rigorous QCISD(T) and RCCSD(T) results indicate that the barrier heights are closer to 3-4 kcal/mol. The calculations therefore indicate that S + C2H2 or S + C2H4 could contribute to the formation of S2 in comets and may serve as a means to gauge coma temperature. The energetics of the ethylene reaction are more favorable.

  16. Petrografía y geoquímica de las anfibolitas del cerro La Cocha, Sierra Chica, Córdoba Petrography and geochemistry of the anphibolites from La Cocha Hill, Sierra Chica, Córdoba, Argentina

    Directory of Open Access Journals (Sweden)

    Patricia A Anzil

    2012-06-01

    Full Text Available En la Sierra Chica de Córdoba, a dos kilómetros al sur del Observatorio Astronómico de Bosque Alegre, se encuentran dos variedades litológicas de anfibolitas asociadas al cuerpo ultramáfico de La Cocha. Estas variedades incluyen anfibolitas sin piroxeno, compuestas por hornblenda, plagioclasa, titanita y minerales opacos, emplazadas en el núcleo de la estructura plegada del cuerpo ultramáfico. El segundo grupo son anfibolitas con dos piroxenos, compuestas por hornblenda, plagioclasa, ortopiroxeno (En, clinopiroxeno (Di y como accesorios minerales opacos, apatita, escasa titanita y circón. Estas anfibolitas se encuentran en el encajonante del cuerpo ultramáfico de La Cocha, asociadas a gneises granatíferos sillimaníticos. Con el objetivo de determinar el protolito, que por metamorfismo dieron origen a las anfibolitas, se realizó un estudio geoquímico de roca total. Las anfibolitas con dos piroxenos se clasifican dentro de la serie toleítica y, en base al diagrama de tierras raras se las podría asociar a un ambiente tectónico de generación de tipo N-MORB. Las anfibolitas sin piroxeno, también corresponderían a un ambiente asimilable a N-MORB, con mayor depresión en las tierras raras livianas, sugiriendo probablemente un ambiente de generación del fundido en un manto empobrecido.In the Sierra Chica of Córdoba (Argentina, two lithological varieties of amphibolites associated with the La Cocha ultramafic body, crops out two kilometer south of the Bosque Alegre Astronomical Observatory. These varieties include non-pyroxene amphibolite composed of hornblende, plagioclase, titanite and opaque minerals, situated in the core of the ultramafic body folded structure. The second group is pyroxene amphibolites comprising hornblende, plagioclase, orthopyroxene (En, clino-pyroxene (Di and accessories including opaque minerals, apatite, more rarely titanite and zircon. This group appears in the ultramafic country rock represented by garnet

  17. 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.

  18. Poluição atmosférica e atendimentos por pneumonia e gripe em São Paulo, Brasil

    Directory of Open Access Journals (Sweden)

    Martins Lourdes Conceição

    2002-01-01

    Full Text Available OBJETIVO: Investigar os efeitos causados pela poluição atmosférica na morbidade por pneumonia e por gripe em idosos entre 1996 e 1998. MÉTODOS: Foram obtidos dados diários de atendimentos por pneumonia e gripe para idosos em pronto-socorro médico de um hospital-escola de referência no Município de São Paulo, SP, Brasil. Os níveis diários de CO, O3, SO2, NO2 e PM10 foram obtidos na Companhia de Tecnologia de Saneamento Ambiental, e os dados diários de temperatura e umidade relativa do ar foram obtidos no Instituto Astronômico e Geofísico da USP. Para verificar a relação existente entre pneumonia e gripe e poluição atmosférica, utilizou-se o modelo aditivo generalizado de regressão de Poisson, tendo como variável dependente o número diário de atendimentos por pneumonia e gripe e como variáveis independentes as concentrações médias diárias dos poluentes atmosféricos. A análise foi ajustada para sazonalidade de longa duração (número de dias transcorridos, sazonalidade de curta duração (dias da semana, temperatura mínima, umidade média, períodos de rodízio e os atendimentos por doenças não-respiratórias em idosos. RESULTADOS: O3 e SO2 estão diretamente associados à pneumonia e à gripe, independentemente das variáveis de controle. Porém, na análise conjunta, eles perdem sua significância estatística. Pôde-se observar que um aumento interquartil (25%-75% para o O3 (38,80 mig/m³ e SO2 (15,05 mig/m³ levaram a um acréscimo de 8,07% e 14,51%, respectivamente, no número de atendimentos por pneumonia e gripe em idosos. CONCLUSÕES: Os resultados sugerem que a poluição atmosférica promove efeitos adversos para a saúde de idosos.

  19. Hα3: an Hα imaging survey of HI selected galaxies from ALFALFA. VI. The role of bars in quenching star formation from z = 3 to the present epoch

    Science.gov (United States)

    Gavazzi, G.; Consolandi, G.; Dotti, M.; Fanali, R.; Fossati, M.; Fumagalli, M.; Viscardi, E.; Savorgnan, G.; Boselli, A.; Gutiérrez, L.; Hernández Toledo, H.; Giovanelli, R.; Haynes, M. P.

    2015-08-01

    redshift evolution for Mknee. Our study highlights how the formation of strong bars in massive galaxies is an important mechanism in regulating the redshift evolution of the sSFR for field main-sequence galaxies. Based on observations taken at the observatory of San Pedro Martir (Baja California, Mexico), belonging to the Mexican Observatorio Astronómico Nacional.

  20. Laboratory and theoretical work in the service of planetary atmospheric research

    Science.gov (United States)

    Coustenis, Athena

    2015-08-01

    . Astron. Astrophys. Rev. 21, #63. [5] Encrenaz, T., et al., 2014. Experimental Astronomy, DOI: 10.1007/s10686-014-9415-0.

  1. On the secular recession of the Earth-Moon system as an azimuthal gravitational phenomenon

    Science.gov (United States)

    Nyambuya, G. G.; Makwanya, T.; Tuturu, B. A.; Tsoka, W.

    2015-07-01

    We here apply the ASTG-model to the observed secular trend in the mean Sun-(Earth-Moon) and Earth-Moon distances thereby providing an alternative explanation as to what the cause of this secular trend may be. Within the margins of observational error; for the semi-major axis rate of the Earth-Moon system, in agreement with observations (of Standish and Kurtz, Proceedings IAU Colloquium, IAU, pp. 163-179, Cambridge University Press, Cambridge, 2005), we obtain a value of about +(5.10±0.10) cm/yr. The ASTG-model predicts orbital drift as being a result of the orbital inclination and the Solar mass loss rate. The Newtonian gravitational constant G is assumed to be an absolute time constant. Krasinsky and Brumberg (Celest. Mech. Dyn. Astron. 90(3-4):267-288, 2004); Standish and Kurtz (2005) reported for the Earth-Moon system, an orbital recession from the Sun of about +(15.00±4.00) cm/yr and +(7.00±2.00) cm/yr respectively; while Williams et al. (Phys. Rev. Lett. 93:261101, 2004); Williams and Boggs (Proceedings of 16th International Workshop on Laser Ranging, Space Research Centre, Polish Academy of Sciences, Poland, 2009), Williams et al. (Planet. Sci. 3(1):2, 2014) report for the Moon, a semi-major axis rate of about +(38.08±0.04) mm/yr from the Earth. The predictions of the ASTG-model for the Earth-Moon system agrees very well with those the findings of Standish and Kurtz (2005), Krasinsky and Brumberg (2004). The lost orbital angular momentum for the Earth-Moon system—which we here hypothesize to be gained as spin by the two body Earth-Moon system; this lost angular momentum accounts very well for the observed Lunar drift, therefore, one can safely say that the ASTG-model does to a reasonable degree of accuracy predict the observed Lunar semi-major axis rate of about +(38.08±0.04) mm/yr from the Earth.

  2. Orbital and physical characteristics of meter-scale impactors from airburst observations

    Science.gov (United States)

    Brown, P.; Wiegert, P.; Clark, D.; Tagliaferri, E.

    2016-03-01

    We have analyzed the orbits and ablation characteristics in the atmosphere of 59 Earth-impacting fireballs, produced by meteoroids 1 m in diameter or larger, described here as meter-scale. Using heights at peak luminosity as a proxy for strength, we determine that there is roughly an order of magnitude spread in strengths of the population of meter-scale impactors at the Earth. We use fireballs producing recovered meteorites and well documented fireballs from ground-based camera networks to calibrate our ablation model interpretation of the observed peak height of luminosity as a function of speed. The orbits and physical strength of these objects are consistent with the majority being asteroidal bodies originating from the inner main asteroid belt. This is in contrast to earlier suggestions by Ceplecha (Ceplecha, Z. [1994]. Astron. Astrophys. 286, 967-970) that the majority of meter-tens of meter sized meteoroids are "… cometary bodies of the weakest known structure". We find a lower limit of ∼10-15% of our objects have a possible cometary (Jupiter-Family comet and/or Halley-type comet) origin based on orbital characteristics alone. Only half this number, however, also show evidence for weaker than average structure. Two events, Sumava and USG 20131121, have exceptionally high (relative to the remainder of the population) heights of peak brightness. These are physically most consistent with high microporosity objects, though both were on asteroidal-type orbits. We also find three events, including the Oct 8, 2009 airburst near Sulawesi, Indonesia, which display comparatively low heights of peak brightness, consistent with strong monolithic stones or iron meteoroids. Based on orbital similarity, we find a probable connection among several events in our population with the Taurid meteoroid complex; no other major meteoroid streams show probable linkages to the orbits of our meter-scale population. Our impactors cover almost four orders of magnitude in mass, but

  3. First survey of Wolf-Rayet star populations over the full extension of nearby galaxies observed with CALIFA

    Science.gov (United States)

    Miralles-Caballero, D.; Díaz, A. I.; López-Sánchez, Á. R.; Rosales-Ortega, F. F.; Monreal-Ibero, A.; Pérez-Montero, E.; Kehrig, C.; García-Benito, R.; Sánchez, S. F.; Walcher, C. J.; Galbany, L.; Iglesias-Páramo, J.; Vílchez, J. M.; González Delgado, R. M.; van de Ven, G.; Barrera-Ballesteros, J.; Lyubenova, M.; Meidt, S.; Falcon-Barroso, J.; Mast, D.; Mendoza, M. A.; Califa Collaboration

    2016-08-01

    binary star channel (which could extend theWR phase up to 10 Myr), fast rotation, or other physical processes that cause the loss of observed Lyman continuum photons, very likely affect the derived WR properties, and hence should be considered when modelling the evolution of massive stars. Based on observations collected at the Centro Astronómico Hispano-Alemán (CAHA) at Calar Alto, operated jointly by the Max-Planck Institut für Astronomie and the Instituto de Astrofísica de Andalucía (CSIC).

  4. VISIR upgrade overview and status

    Science.gov (United States)

    Kerber, Florian; Käufl, Hans-Ulrich; Baksai, Pedro; Di Lieto, Nicola; Dobrzycka, Danuta; Duhoux, Philippe; Finger, Gert; Heikamp, Stephanie; Ives, Derek; Jakob, Gerd; Lundin, Lars; Mawet, Dimitri; Mehrgan, Leander; Momany, Yazan; Moreau, Vincent; Pantin, Eric; Riquelme, Miguel; Sandrock, Stefan; Siebenmorgen, Ralf; Smette, Alain; Taylor, Julian; van den Ancker, Mario; Valdes, Guillermo; Venema, Lars; Weilenmann, Ueli

    2014-07-01

    We present an overview of the VISIR upgrade project. VISIR is the mid-infrared imager and spectrograph at ESO's VLT. The project team is comprised of ESO staff and members of the original VISIR consortium: CEA Saclay and ASTRON. The project plan is based on input from the ESO user community with the goal of enhancing the scientific performance and efficiency of VISIR by a combination of measures: installation of improved hardware, optimization of instrument operations and software support. The cornerstone of the upgrade is the 1k by 1k Si:As AQUARIUS detector array (Raytheon) which has been carefully characterized in ESO's IR detector test facility (modified TIMMI 2 instrument). A prism spectroscopic mode will cover the N-band in a single observation. New scientific capabilities for high resolution and high-contrast imaging will be offered by sub-aperture mask (SAM) and phase-mask coronagraphic (4QPM/AGPM) modes. In order to make optimal use of favourable atmospheric conditions a water vapour monitor has been deployed on Paranal, allowing for real-time decisions and the introduction of a user-defined constraint on water vapour. During the commissioning in 2012 it was found that the on-sky sensitivity of the AQUARIUS detector was significantly below expectations and that VISIR was not ready to go back to science operations. Extensive testing of the detector arrays in the laboratory and on-sky enabled us to diagnose the cause for the shortcoming of the detector as excess low frequency noise (ELFN). It is inherent to the design chosen for this detector and can't be remedied by changing the detector set-up. Since this is a form of correlated noise its impact can be limited by modulating the scene recorded by the detector. We have studied several mitigation options and found that faster chopping using the secondary mirror (M2) of the VLT offers the most promising way forward. Faster M2 chopping has been tested and is scheduled for implementation before the end of 2014

  5. Sistemas Correctores de Campo Para EL Telescopio Cassegrain IAC80

    Science.gov (United States)

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

    1987-05-01

    El proyecto de instrumentación de mayor importancia que ha tenido el Instituto de Astrofisica de Canarias en los últimos afios ha sido el diseflo y construcción del te1escopio IAC8O. Este requería del esfuerzo con junto en mec´nica, óptica y electrónica, lo que facilitó la estructuración y el crecimiento de los respectivos grupos de trabajo, que posteriormente se integraron en departamentos En su origen (1977), el telescopio IAC80 fue concebido como un sistema clásico tipo Cassegrain, con una razón focal F/i 1.3 para el sistema Casse grain y una razón focal F/20 para el sistema Coudé. Posteriormente, aunque se mantuvo la filosofia de que el sistema básico fuera el F/11.3, se consideró conveniente el diseño de secundarios para razones focales F/16 y F/32, y se eliminó el de F/20. Sin embargo, dada la importancia relativa que un foco estrictamente fotográfico tiene en un telescopio moderno, diseñado básicamente para fotometría fotoeléctrica y con un campo util mínimamente de 40 minutos de arco, se decídió Ilevar a cabo el diseño de un secundario F/8 con un sistema corrector de campo, pero que estuviera formado únicamente por lentes con superficies esféricas para que asl su construcción fuera posible en España ó en México. La creciente utilización de detectores bidimensionales para fines de investigación astron6mica y la viabilidad de que en un futuro cercano éstos tengan un área sensible cada vez mayor, hicieron atractiva la idea de tener diseñado un sistema corrector de campo para el foco primario (F/3), con un campo útil mínimo de un grado, y también con la limitante de que sus componentes tuvieron sólamente supérficies esféricas. Ambos diseños de los sis-temas correctores de campo se llevaron a cabo, en gran medida, como parte de un proyecto de colaboración e intercambio en el área de diseño y evaluación de sistemas ópticos.

  6. Var C: Long-term photometric and spectral variability of a luminous blue variable in M 33

    Science.gov (United States)

    Burggraf, B.; Weis, K.; Bomans, D. J.; Henze, M.; Meusinger, H.; Sholukhova, O.; Zharova, A.; Pellerin, A.; Becker, A.

    2015-09-01

    Aims: So far the highly unstable phase of luminous blue variables (LBVs) has not been understood well. It is still uncertain why and which massive stars enter this phase. Investigating the variabilities by looking for a possible regular or even (semi-)periodic behaviour could give a hint at the underlying mechanism for these variations and might answer the question of where these variabilities originate. Finding out more about the LBV phase also means understanding massive stars better in general, which have (e.g. by enriching the ISM with heavy elements, providing ionising radiation and kinetic energy) a strong and significant influence on the ISM, hence also on their host galaxy. Methods: Photometric and spectroscopic data were taken for the LBV Var C in M 33 to investigate its recent status. In addition, scanned historic plates, archival data, and data from the literature were gathered to trace Var C's behaviour in the past. Its long-term variability and periodicity was investigated. Results: Our investigation of the variability indicates possible (semi-)periodic behaviour with a period of 42.3 years for Var C. That Var C's light curve covers a time span of more than 100 years means that more than two full periods of the cycle are visible. The critical historic maximum around 1905 is less strong but discernible even with the currently rare historic data. The semi-periodic and secular structure of the light curve is similar to the one of LMC R71. Both light curves hint at a new aspect in the evolution of LBVs. Based on observations collected at the Thüringer Landessternwarte (TLS) Tautenburg.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).Tables 2-4, and 6 are available in electronic form at http://www.aanda.org

  7. A Tri-band Cryogenic Receiver for the RAEGE Project Antennas

    Science.gov (United States)

    López-Pérez, J. A.; Tercero, F.; Serna, J. M.; López-Fernández, J. A.

    2012-12-01

    The Spanish Centro de Desarrollos Tecnológicos (CDT) is developing a tri-band cryogenic receiver for the first light observations of the first RAEGE project antenna in Centro Astronómico de Yebes observatory in the framework of the VLBI2010 project. The RAEGE project plans to install three new ring-focus 13.2 meter antennas in compliance with the VLBI2010 specifications. These antennas are under construction. The first light receiver envisaged for these antennas will operate in the S (2.2 — 2.7 GHz), X (7.5 — 9 GHz), and Ka (28 — 33 GHz) bands, simultaneously, in order to be backward compatible with non-VLBI2010 stations and forward compatible with new ones. The receiver feed designed to illuminate the ring-focus antenna is made of a coaxial waveguide, for the S and X bands, and a circular waveguide for the Ka band. Four outputs from their corresponding field probes at S and X bands must be combined with 180 ° and 90 ° hybrid circuits to get simultaneous dual-circular polarization. In the Ka band case, the two circular polarizations are split by means of a classical septum polarizer. The feed, hybrids, and polarizer will operate at cryogenic temperature in order to minimize their contribution to system noise. The estimated equivalent noise temperature for this receiver is lower than 15 Kelvin for S-band, 20 Kelvin for X-band, and 25 Kelvin for Ka-band. The output signals from the cryostat will be sent to their corresponding room temperature downconverters for later amplification, filtering, and mixing. The final IF signal will range from 500 to 1000 MHz, as in a classical geodetic VLBI receiver, to be backward compatible with non-VLBI2010 stations. An advantage of having the Ka band receiver is that it will allow the radiometric characterization (pointing, tracking, and efficiency) of these antennas during commissioning. In addition, simultaneous X/Ka operation would be possible. The first receiver of this type is planned to be finished by September, 2012

  8. Prospective Work for Alma: the Millimeterwave and Submillimeterwave Spectrum of 13C-GLYCOLALDEHYDE

    Science.gov (United States)

    Haykal, Imane; Margulès, Laurent; Huet, Therese R.; Motiyenko, Roman; Guillemin, J.-C.

    2011-06-01

    Glycolaldehyde has been identified in interstellar sources. The relative abundance ratios of the three isomers (acetic acid) : (glycolaldehyde) : (methylformate) were estimated . The detection of 13C_1 and 13C_2 isotopomers of methylformate has been recently reported in Orion, as a result of the detailled labororatory spectroscopic study. Therefore the spectroscopy of the 13C isotopomers of glycolaldehyde is investigated in laboratory in order to provide data for an astronomical search. The instrument ALMA will certainly be a good instrument to detect them. Up to now, only the microwave spectra of 13CH_2OH-CHO and of CH_2OH-13CHO have been observed several years ago in the 12-40 GHz range. Spectra of both species are presently recorded in Lille in the 150-950 GHz range with the new submillimetre-wave spectrometer based on harmonic generation of a microwave synthesizer source, using only solid-state devices, and coupled to a cell of 2.2 m length The absolute accuracy of the line positions is better than 30 KHz. The rotational structure of the ground state and of the three first excited vibrational states has been observed. Two 13C enriched samples were used. The analysis is in progress. This work is supported by the Programme National de Physico-Chimie du Milieu Interstellaire (PCMI-CNRS) and by the contract ANR-08-BLAN-0054 J. M. Hollis, S. N. Vogel, L. E. Snyder, et al., Astrophys. J. 554(2001) L81 R. A. H. Butler, F. C. De Lucia, D. T Petkie, et al., Astrophys. J. Supp. 134 (2001) 319 M. T. Beltran, C. Codella, S. Viti, R. Niri, R. Cesaroni, Astrophys. J. 690 (2009) L93. M. Carjaval, L. Margulès, B. Tercero et al., Astron. Astrophys. 500 (2009) 1109. K.-M. Marstokk and H. Møllendal, J. Mol. Struct. 16 (1973) 259. R. A. Motiyenko, L. Margulès, E. A. Alekseev et al., J. Mol. Spectrosc. 264 (2010) 94.

  9. Photochemistry in Saturn's Ring-Shadowed Atmosphere: Modeling of Key Molecules and Observations of Dust Content

    Science.gov (United States)

    Edgington, S. G.; Atreya, S. K.; Wilson, E. H.; West, R. A.; Fletcher, L. N.; Baines, K. H.; Bjoraker, G. L.; Momary, T.

    2014-12-01

    -generated molecules and haze. [1] Edgington, S.G., et al., 2012. Photochemistry in Saturn's Ring Shadowed Atmosphere: Modeling, Observations, and Preliminary Analysis. Bull. American. Astron. Soc., 38, 499 (#11.23).

  10. Photochemistry in Saturn’s Ring-Shadowed Atmosphere: Modeling of Key Molecules and Observations of Dust Content

    Science.gov (United States)

    Edgington, Scott G.; Atreya, Sushil K.; Wilson, Eric H.; West, Robert A.; Baines, Kevin H.; Bjoraker, Gordon L.; Fletcher, Leigh N.; Momary, Tom

    2014-11-01

    -generated molecules and haze. [1] Edgington, S.G., et al., 2012. Photochemistry in Saturn’s Ring Shadowed Atmosphere: Modeling, Observations, and Preliminary Analysis. Bull. American. Astron. Soc., 38, 499 (#11.23).

  11. Photochemistry in Saturn’s Ring-Shadowed Atmosphere: Venetian Blinds, Atmospheric Molecules and Observations

    Science.gov (United States)

    Edgington, Scott G.; Atreya, S. K.; Wilson, E. H.; Baines, K. H.; West, R. A.; Bjoraker, G. L.; Fletcher, L. N.; Momary, T.

    2013-10-01

    dynamical mixing. [1] Edgington, S.G., et al., 2012. Photochemistry in Saturn’s Ring Shadowed Atmosphere: Modeling, Observations, and Preliminary Analysis. Bull. American. Astron. Soc., 38, 499 (#11.23).

  12. Photochemistry in Saturn's Ring-Shadowed Atmosphere: Modulation of Key Molecules and Observations of Dust Content

    Science.gov (United States)

    Edgington, Scott G.; Atreya, Sushil H.; Wilson, Eric H.; Baines, Kevin H.; West, Robert A.; Bjoraker, Gordon L.; Fletcher, Leigh N.; Momary, Tom

    2015-04-01

    -generated molecules and haze. [1] Edgington, S.G., et al., 2012. Photochemistry in Saturn's Ring Shadowed Atmosphere: Modeling, Observations, and Preliminary Analysis. Bull. American. Astron. Soc., 38, 499 (#11.23).

  13. Photochemistry in Saturn's Ring-Shadowed Atmosphere: Of Venetian Blinds, Atmospheric Molecules and Observations

    Science.gov (United States)

    Edgington, S. G.; Atreya, S. K.; Wilson, E. H.; Baines, K. H.; West, R. A.; Bjoraker, G. L.; Fletcher, L. N.; Momary, T.

    2013-12-01

    dynamical mixing. [1] Edgington, S.G., et al., 2012. Photochemistry in Saturn's Ring Shadowed Atmosphere: Modeling, Observations, and Preliminary Analysis. Bull. American. Astron. Soc., 38, 499 (#11.23).

  14. OJ 287 and the predicted fade of 1998

    Science.gov (United States)

    Pietilä, H.; Takalo, L. O.; Tosti, G.; Benítez, E.; Chiattelli, B.; Corradi, R. L. M.; Cox, G.; de Diego, J. A.; de Francesco, G.; Dultzin-Hacyan, D.; Heinämäki, P.; Katajainen, S.; Keinänen, P.; Korhonen, H.; Kotilainen, J.; Lainela, M.; Licandro, J.; Luciani, M.; Nilsson, K.; Pursimo, T.; Raiteri, C. M.; Rekola, R.; Sillanpää, A.; Sobrito, G.; Teräsranta, H.; Villata, M.; Zurita, A.

    1999-05-01

    There were predictions that blazar OJ 287 should have faded in late 1997 or early 1998. The observational background for these predictions is the sudden fade of OJ 287 in 1989. Back then, the radio flux decreased steadily for 4-5 months and then the brightness dropped also in the optical region suddenly for 2-3 weeks to all time low values, e.g. V=17.4 mag. The predictions are based on a binary black hole model, where the companion black hole and its accretion disk eclipse the emission areas of the primary black hole. We have made observations of OJ 287 during the time of the predicted fade. The results show that, in the optical, OJ 287 starts to fade almost linearly in December 1997 until mid-February 1998, when it suddenly shows a sharp rise and sharp fade, and starts to get brighter again. The radio observations show no signs of variability, but the radio flux has been very low since the 1995 outburst. We also have earlier observations since Fall 1993 to Spring 1998, which show that the local minimum reached in February 1998 was the lowest since 1995. We have made observations with several telescopes in the optical (UBVRI) and radio (22 and 37 GHz) bands. We discuss the various events in the light curves and their implications on the proposed models, especially the binary black hole model by Lehto & Valtonen (\\cite{lv96}), which was used to make the prediction of the time of the fade. Based on observations made with the Nordic Optical Telescope, operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway, and Sweden, in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias, observations at the Perugia Observatory, Perugia, Italy, observations at the Observatorio Astronómico Nacional, San Pedro Mártir, Baja California, México, observations at the Torino Observatory, Torino, Italy, observations at the Tuorla Observatory, Piikkiö, Finland, and observations at the Metsähovi Radio Research Station

  15. Binary asteroid population. 3. Secondary rotations and elongations

    Science.gov (United States)

    Pravec, P.; Scheirich, P.; Kušnirák, P.; Hornoch, K.; Galád, A.; Naidu, S. P.; Pray, D. P.; Világi, J.; Gajdoš, Š.; Kornoš, L.; Krugly, Yu. N.; Cooney, W. R.; Gross, J.; Terrell, D.; Gaftonyuk, N.; Pollock, J.; Husárik, M.; Chiorny, V.; Stephens, R. D.; Durkee, R.; Reddy, V.; Dyvig, R.; Vraštil, J.; Žižka, J.; Mottola, S.; Hellmich, S.; Oey, J.; Benishek, V.; Kryszczyńska, A.; Higgins, D.; Ries, J.; Marchis, F.; Baek, M.; Macomber, B.; Inasaridze, R.; Kvaratskhelia, O.; Ayvazian, V.; Rumyantsev, V.; Masi, G.; Colas, F.; Lecacheux, J.; Montaigut, R.; Leroy, A.; Brown, P.; Krzeminski, Z.; Molotov, I.; Reichart, D.; Haislip, J.; LaCluyze, A.

    2016-03-01

    We collected data on rotations and elongations of 46 secondaries of binary and triple systems among near-Earth, Mars-crossing and small main belt asteroids. 24 were found or are strongly suspected to be synchronous (in 1:1 spin-orbit resonance), and the other 22, generally on more distant and/or eccentric orbits, were found or are suggested to have asynchronous rotations. For 18 of the synchronous secondaries, we constrained their librational angles, finding that their long axes pointed to within 20° of the primary on most epochs. The observed anti-correlation of secondary synchroneity with orbital eccentricity and the limited librational angles agree with the theories by Ćuk and Nesvorný (Ćuk, M., Nesvorný, D. [2010]. Icarus 207, 732-743) and Naidu and Margot (Naidu, S.P., Margot, J.-L. [2015]. Astron. J. 149, 80). A reason for the asynchronous secondaries being on wider orbits than synchronous ones may be longer tidal circularization time scales at larger semi-major axes. The asynchronous secondaries show relatively fast spins; their rotation periods are typically synchronous secondaries with greater elongations appears consistent, considering uncertainties of the axis ratio estimates, with the theory by Ćuk and Nesvorný that predicts large regions of chaotic rotation in the phase space for a2 /b2 ≳√{ 2 } . Alternatively, secondaries may not form or stay very elongated in gravitational (tidal) field of the primary. It could be due to the secondary fission mechanism suggested by Jacobson and Scheeres (Jacobson, S.A., Scheeres, D.J. [2011]. Icarus 214, 161-178), as its efficiency is correlated with the secondary elongation. Sharma (Sharma, I. [2014]. Icarus 229, 278-294) found that rubble-pile satellites with a2 /b2 ≲ 1.5 are more stable to finite structural perturbations than more elongated ones. It appears that more elongated secondaries, if they originally formed in spin fission of parent asteroid, are less likely to survive intact and they more

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

    Science.gov (United States)

    Tennyson, J.; Barber, R. J.; Azzam, A.; Down, M.; Hill, C.; Yurchenko, S. N.

    2011-06-01

    such as ammonia, acetylene, hydrogen peroxide and formaldehyde, are at the very limit of what is computationally possible at present. These will be computed either by direct calculation of the full line list, such as our hot ammonia line list BYTe developed recently [S. N. Yurchenko, R. J. Barber , and J. Tennyson, Mon. Not. R. Astron. Soc., in press, (2011)], or by use of high accuracy vibrational calculations onto which the rotational structure will be grafted using ideas developed from the standard perturbation theory approach to molecular spectroscopy. Tests for acetylene suggest that this latter approach, although intrinsically less accurate, is still able to give reliable results [A. Urru, I. N. Kozin, G. Mulas, B. J. Braams, and J. Tennyson, Mol. Phys., 108, 1973 (2010)]. Data from this project can be accessed at www.exomol.com.

  17. Investigation of a transiting planet candidate in Trumpler 37: An astrophysical false positive eclipsing spectroscopic binary star

    Science.gov (United States)

    Errmann, R.; Torres, G.; Schmidt, T. O. B.; Seeliger, M.; Howard, A. W.; Maciejewski, G.; Neuhäuser, R.; Meibom, S.; Kellerer, A.; Dimitrov, D. P.; Dincel, B.; Marka, C.; Mugrauer, M.; Ginski, Ch.; Adam, Ch.; Raetz, St.; Schmidt, J. G.; Hohle, M. M.; Berndt, A.; Kitze, M.; Trepl, L.; Moualla, M.; Eisenbeiß, T.; Fiedler, S.; Dathe, A.; Graefe, Ch.; Pawellek, N.; Schreyer, K.; Kjurkchieva, D. P.; Radeva, V. S.; Yotov, V.; Chen, W. P.; Hu, S. C.-L.; Wu, Z.-Y.; Zhou, X.; Pribulla, T.; Budaj, J.; Vaňko, M.; Kundra, E.; Hambálek, Ľ.; Krushevska, V.; Bukowiecki, Ł.; Nowak, G.; Marschall, L.; Terada, H.; Tomono, D.; Fernandez, M.; Sota, A.; Takahashi, H.; Oasa, Y.; Briceño, C.; Chini, R.; Broeg, C. H.

    We report our investigation of the first transiting planet candidate from the YETI project in the young (˜4 Myr old) open cluster Trumpler 37. The transit-like signal detected in the lightcurve of F8V star 2M21385603+5711345 repeats every 1.364894±0.000015 days, and has a depth of 54.5±0.8 mmag in R. Membership in the cluster is supported by its mean radial velocity and location in the color-magnitude diagram, while the Li diagnostic and proper motion are inconclusive in this regard. Follow-up photometric monitoring and adaptive optics imaging allow us to rule out many possible blend scenarios, but our radial-velocity measurements show it to be an eclipsing single-lined spectroscopic binary with a late-type (mid-M) stellar companion, rather than one of planetary nature. The estimated mass of the companion is 0.15-0.44 M⊙. The search for planets around very young stars such as those targeted by the YETI survey remains of critical importance to understand the early stages of planet formation and evolution. Based in part on data collected at Subaru Telescope, which is operated by the National Astronomical Observatory of Japan. Some of the data presented herein were obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration (Proposal ID H215Hr). The Observatory was made possible by the generous financial support of the W.M. Keck Foundation. Based on observations obtained with telescopes of the University Observatory Jena, which is operated by the Astrophysical Institute of the Friedrich-Schiller-University. Based on observations collected at the Centro Astronómico Hispano Alemán (CAHA) at Calar Alto, operated jointly by the Max-Planck Institut für Astronomie and the Instituto de Astrofísica de Andalucía (CSIC, Proposal IDs H10-3.5-015 and H10-2.2-004). Some of the observations reported here were obtained at

  18. Induction Linac Pulsers

    International Nuclear Information System (INIS)

    The pulsers used in most of the induction linacs evolved from the very large body of work that was done in the U.S. and Great Britain during the development of the pulsed magnetron for radar. The radar modulators started at ∼100 kW and reached >10 MW by 1945. A typical pulse length was 1 μs at a repetition rate of 1,000 pps. A very comprehensive account of the modulator development is Pulse Generators by Lebacqz and Glasoe, one of the Radiation Laboratory Series. There are many permutations of possible modulators, two of the choices being tube type and line type. In earlier notes I wrote that technically the vacuum tube pulser met all of our induction linac needs, in the sense that a number of tubes, in series and parallel if required, could produce our pulses, regulate their voltage, be useable in feed-forward correctors, and provide a low source impedance. At a lower speed, an FET array is similar, and we have obtained and tested a large array capable of >10 MW switching. A modulator with an electronically controlled output only needs a capacitor for energy storage and in a switched mode can transfer the energy from the capacitor to the load at high efficiency. Driving a full size Astron induction core and a simulated resistive 'beam load' we achieved >50% efficiency. These electronically controlled output pulses can produce the pulses we desire but are not used because of their high cost. The second choice, the line type pulser, visually comprises a closing switch and a distributed or a lumped element transmission line. The typical switch cannot open or stop conducting after the desired pulse has been produced, and consequently all of the initially stored energy is dissipated. This approximately halves the efficiency, and the original cost estimating program LIACEP used this factor of two, even though our circuits are usually worse, and even though our inveterate optimists often omit it. The 'missing' energy is that which is reflected back into the line from

  19. Mass decomposition of SLACS lens galaxies in Weyl conformal gravity

    Science.gov (United States)

    Potapov, Alexander A.; Izmailov, Ramil N.; Nandi, Kamal K.

    2016-06-01

    We study here, using the Mannheim-Kazanas solution of Weyl conformal theory, the mass decomposition in the representative subsample of 57 early-type elliptical lens galaxies of the Sloan Lens Advanced Camera for Surveys (SLACS) on board the Hubble Space Telescope. We begin by showing that the solution need not be an exclusive solution of conformal gravity but can also be viewed as a solution of a class of f (R ) gravity theories coupled to nonlinear electrodynamics thereby rendering the ensuing results more universal. Since lensing involves light bending, we shall first show that the solution adds to Schwarzschild light bending caused by the luminous mass (M*) a positive contribution +γ R contrary to the previous results in the literature, thereby resolving a long-standing problem. The cause of the error is critically examined. Next, applying the expressions for light bending together with an input equating Einstein and Weyl angles, we develop a novel algorithm for separating the luminous component from the total lens mass (luminous+dark ) within the Einstein radius. Our results indicate that the luminous mass estimates differ from the observed total lens masses by a linear proportionality factor across the subsample, which qualitatively agrees with the common conclusion from a number of different simulations in the literature. In quantitative detail, we observe that the ratios of luminous over total lens mass (f*) within the Einstein radius of individual galaxies take on values near unity, many of which remarkably fall inside or just marginally outside the specified error bars obtained from a simulation based on the Bruzual-Charlot stellar population synthesis model together with the Salpeter initial mass function favored on the ground of metallicity [Grillo et al., Astron. Astrophys. 501, 461 (2009)]. We shall also calculate the average dark matter density ⟨ρ⟩ av of individual galaxies within their respective Einstein spheres. To our knowledge, the present

  20. Tiempo e historia en el Islam

    Directory of Open Access Journals (Sweden)

    Viguera Molins, María Jesús

    2004-06-01

    Full Text Available As in other civilizations, time in Islam is one of the organizing principies of its concepts, representations and identity. The very emergence of this civilization, in 7thcentury Arabia, resulted in the establishment of an era, a calendar and an historical consciousness of its own. Within this specificity, there are different ways of understanding, living and feeling time and history: from the personal, subjective perspective to that of philosophers and astronomers to time in the organization of daily activities, and from history as a succession of reigns and dynasties. These different concepts and vantage points reflect the richness and complexity of a civilization that is currently spread across all five continents and more than 1400 years old since Hegira. Thus, for the "orthodox" Sunnites time is linear, whereas for the Shiites it is cyclical. Yet even the rationalization of history as a linear occurring is not free from a contested meaning relative to the political circumstances of the present, as a semantic analysis of the term dawla indicates.

    Como en otras civilizaciones, el tiempo en el Islam es uno de los principios organizativos de sus conceptos, sus representaciones y su identidad. El mismo surgimiento de esta civilización, en la Arabia del siglo VII de la Era Cristiana, supuso la constitución de una era, un calendario y una conciencia histórica propios. Dentro de esta especificidad, hay diferentes modos de entender, vivir y sentir el transcurso del tiempo y de la historia, desde una perspectiva personal y subjetiva a otra social y política en relación con reinados y dinastías, pasando por la misma organización de las actividades cotidianas y la producción filosófica y astronómica. Estas diferencias reflejan la riqueza y complejidad de una civilización que se extiende hoy por todos los continentes y sobrepasa los 1400 años desde la Hégira. Entre los sunníes u "ortodoxos", por ejemplo, el tiempo

  1. Pilot Search for 54-MHz Maser Emission from Interstellar Hydroxyl Using LOFAR

    Science.gov (United States)

    Hoffman, Ian M.; Heald, G.; Oonk, R.; McKean, J.; Mol, J.; Hessels, J.; Toribio, C.; LOFAR Collaboration

    2014-01-01

    We present the results of the most sensitive search to date for the two 54-MHz spectral lines of the hydroxyl (OH) molecule. These are the preliminary results of a larger, planned observational campaign. The splitting of the rotational ground state of the hydroxyl molecule gives rise to the four familiar 1.7-GHz transitions by which OH is known in the interstellar medium. There are also two magnetic-dipole transitions among these states at frequencies of 53.2 MHz and 55.1 MHz. These 54-MHz transitions have never been detected astronomically. Because of the relative weakness of the magnetic-dipole emission process, it is expected that only maser emission will generate a detectable 54-MHz signal. Two previous searches have been conducted by other authors with other instruments toward Galactic sources of known 1720-MHz OH maser emission: three sources were searched at 55.1 MHz and two other sources were searched at 53.2 MHz, resulting in upper limits of approximately 30 Jy for spectral channels of 2 km/s in width. In preparation for our future observational campaign that will apply the unprecedented sensitivity of LOFAR to the search for 54-MHz OH emission, we conducted a pilot project using six hours of Commissioning Time. These observations employed 21 48-element stations and produced a spectral resolution of approximately 0.5 km/s for both the 53.2- and 55.1-MHz lines. This spectral resolution is a considerable improvement over previous searches since it is suitable both for resolving the characteristically narrow width of maser lines and for identifying radiofrequency interference. In our pilot observations, no emission was detected at either frequency with an upper limit of approximately 3 Jy. We observed the Galactic sources W75N and W3(OH), neither of which have been searched previously at either frequency. We discuss the astrophysical implications of these sensitive non-detections. LOFAR, the Low Frequency Array designed and constructed by ASTRON, has

  2. A Continuing Analysis of Possible Activity Drivers for the Enigmatic Comet 29P/Schwassmann-Wachmann 1

    Science.gov (United States)

    Schambeau, Charles; Fernández, Yanga; Samarasinha, Nalin H.; Mueller, Beatrice E. A.; Sarid, Gal; Meech, Karen Jean; Woodney, Laura

    2016-01-01

    We present results from our effort to understand activity drivers in Comet 29P/Schwassmann-Wachmann 1 (SW1). In a nearly circular orbit around 6 AU, outside of the water-sublimation zone, SW1 is continuously active and experiences frequent outbursts. Our group's effort is focusing on finding constraints on physical and dynamical properties of SW1's nucleus and their incorporation into a thermophysical model [1,2] to explain this behavior. We are currently analyzing coma morphology of SW1 before, during, and after outburst placing constraints on the spin-pole direction, spin period, and surface areas of activity. In addition, we are using the thermal model to investigate if the continuous activity comes from one or multiple processes, such as the release of trapped supervolatiles during the amorphous to crystalline (A-C) water ice phase transition and/or the direct sublimation of pockets of supervolatile ices. The supervolatile ices may be primordial or from the condensation of gases released during the A-C phase transition. To explain the possibly quasi-periodic but frequent outbursts, we are looking into subsurface cavities where internal pressures can build, reaching and exceeding surrounding material strengths [3,4] and/or thermal waves reaching a pocket of supervolatile ices, causing a rapid increase in the sublimation rate. For all these phenomena, the model is constrained by comparing the output dust mass loss rate and its variability with what has been observed through optical imaging of the comet at various points in its orbit. We will present preliminary thermal modeling of a homogeneous progenitor nucleus that evolves into a body showing internal material layering, the generation of CO and CO2 ice pockets, and the production of outbursts, thus bringing us closer to explaining the behavior of this intriguing comet. [1] Sarid, G., et al.: 2005, PASP, 117, 843. [2] Sarid, G.: 2009, PhD Thesis, Tel Aviv Univ. [3] Gronkowski, P., 2014, Astron. Nachr./AN 2, No

  3. Positron astrophysics and areas of relation to low-energy positron physics

    International Nuclear Information System (INIS)

    I briefly review our general knowledge of positron astrophysics, focusing mostly on the theoretical and modelling aspects. The experimental/observational aspects of the topic have recently been reviewed elsewhere [E. Churazov et al., Mon. Nat. R. Astron. Soc. 411, 1727 (2011); N. Prantazos et al., Rev. Mod. Phys. 83, 1001 (2011)]. In particular, I highlight the interactions and cross sections of the reactions that the positrons undergo in various cosmic media. Indeed, these must be of high interest to both the positron astrophysics community and the low-energy positron physics community in trying to find common areas of potential collaboration for the future or areas of research that will help the astrophysics community make further progress on the problem. The processes undergone by positrons from the moments of their birth to their annihilation (in the interstellar medium or other locations) are thus examined. The physics of the positron interactions with gases and solids (dust grains) and the physical conditions and characteristics of the environments where the processes of energy loss, positronium formation, and annihilation take place, are briefly reviewed. An explanation is given about how all the relevant physical information is taken into account in order to calculate annihilation rates and spectra of the 511 keV emission in the ISM; special attention is paid to positron interactions with dust and with polycyclic aromatic hydrocarbons. In particular, an attempt is made to show to what extent the interactions between positrons and interstellar dust grains are similar to laboratory experiments in which beams of low-energy positrons impinge upon solids and surfaces. Sample results are shown for the effect of dust grains on positron annihilation spectra in some phases of the ISM which, together with high resolution spectra measured by satellites, can be used to infer useful knowledge about the environment where the annihilation is predominantly taking place

  4. A characteristic oxygen abundance gradient in galaxy disks unveiled with CALIFA

    Science.gov (United States)

    Sánchez, S. F.; Rosales-Ortega, F. F.; Iglesias-Páramo, J.; Mollá, M.; Barrera-Ballesteros, J.; Marino, R. A.; Pérez, E.; Sánchez-Blazquez, P.; González Delgado, R.; Cid Fernandes, R.; de Lorenzo-Cáceres, A.; Mendez-Abreu, J.; Galbany, L.; Falcon-Barroso, J.; Miralles-Caballero, D.; Husemann, B.; García-Benito, R.; Mast, D.; Walcher, C. J.; Gil de Paz, A.; García-Lorenzo, B.; Jungwiert, B.; Vílchez, J. M.; Jílková, Lucie; Lyubenova, M.; Cortijo-Ferrero, C.; Díaz, A. I.; Wisotzki, L.; Márquez, I.; Bland-Hawthorn, J.; Ellis, S.; van de Ven, G.; Jahnke, K.; Papaderos, P.; Gomes, J. M.; Mendoza, M. A.; López-Sánchez, Á. R.

    2014-03-01

    galactocentric distance, the oxygen abundance seems to be correlated well with the stellar mass density and total stellar mass of the galaxies, independently of other properties of the galaxies. Other processes, such as radial mixing and inflows/outflows seem to have a limited effect on shaping of the radial distribution of oxygen abundances, although they are not ruled out. Appendices are available in electronic form at http://www.aanda.orgBased 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).

  5. Two new pulsating low-mass pre-white dwarfs or SX Phoenicis stars?

    Science.gov (United States)

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

    2016-03-01

    Context. The discovery of pulsations in low-mass stars opens an opportunity to probe their interiors and determine their evolution by employing the tools of asteroseismology. Aims: We aim to analyse high-speed photometry of SDSS J145847.02+070754.46 and SDSS J173001.94+070600.25 and discover brightness variabilities. In order to locate these stars in the Teff - log g diagram, we fit optical spectra (SDSS) with synthetic non-magnetic spectra derived from model atmospheres. Methods: To carry out this study, we used the photometric data we obtained for these stars with the 2.15 m telescope at CASLEO, Argentina. We analysed their light curves and applied the discrete Fourier transform (FT) to determine the pulsation frequencies. Finally, we compare both stars in the Teff - log g diagram, with two known pre-white dwarfs and seven pulsating pre-ELM white dwarf stars, δ Scuti, and SX Phe stars Results: We report the discovery of pulsations in SDSS J145847.02+070754.46 and SDSS J173001.94+070600.25. We determine their effective temperature and surface gravity to be Teff = 7972 ± 200 K, log g = 4.25 ± 0.5 and Teff = 7925 ± 200 K, log g = 4.25 ± 0.5, respectively. With these parameters, these new pulsating low-mass stars can be identified with either ELM white dwarfs (with ~0.17 M⊙) or more massive SX Phe stars. We identified pulsation periods of 3278.7 and 1633.9 s for SDSS J145847.02+070754.46 and a pulsation period of 3367.1 s for SDSS J173001.94+070600.25. These two new objects, together with those of Maxted et al. (2013, 2014), indicate the possible existence of a new instability domain towards the late stages of evolution of low-mass white dwarf stars, although their identification with SX Phe stars cannot be discarded. Visiting Astronomer, Complejo Astronómico El Leoncito operated under agreement between the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina and the National Universities of La Plata, Córdoba, and San Juan.

  6. Departure from the constant-period ephemeris for the transiting exoplanet WASP-12

    Science.gov (United States)

    Maciejewski, G.; Dimitrov, D.; Fernández, M.; Sota, A.; Nowak, G.; Ohlert, J.; Nikolov, G.; Bukowiecki, Ł.; Hinse, T. C.; Pallé, E.; Tingley, B.; Kjurkchieva, D.; Lee, J. W.; Lee, C.-U.

    2016-04-01

    Aims: Most hot Jupiters are expected to spiral in toward their host stars because the angular momentum of the orbital motion is transferred to the stellar spin. Their orbits can also precess as a result of planet-star interactions. Calculations show that both effects might be detected for the very-hot exoplanet WASP-12 b using the method of precise transit-timing over a time span of about 10 yr. Methods: We acquired new precise light curves for 29 transits of WASP-12 b, spannning four observing seasons from November 2012 to February 2016. New mid-transit times, together with those from the literature, were used to refine the transit ephemeris and analyze the timing residuals. Results: We find that the transit times of WASP-12 b do not follow a linear ephemeris with a 5σ confidence level. They may be approximated with a quadratic ephemeris that gives a change rate in the orbital period of (-2.56 ± 0.40) × 10-2 s yr-1. The tidal quality parameter of the host star was found to be equal to 2.5 × 105, which is similar to theoretical predictions for Sun-like stars. We also considered a model in which the observed timing residuals are interpreted as a result of the apsidal precession. We find, however, that this model is statistically less probable than the orbital decay. Partly based on (1) data collected with the Nordic Optical Telescope, operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway, and Sweden, in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias, (2) observations made at the Centro Astronómico Hispano Alemán (CAHA), operated jointly by the Max-Planck Institut für Astronomie and the Instituto de Astrofísica de Andalucía (CSIC), and (3) data collected with telescopes at the Rozhen National Astronomical Observatory.The light curves are available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/588/L

  7. Identification of New Hot Bands in the Blue and Green Band Systems of FeH.

    Science.gov (United States)

    Wilson; Brown

    1999-10-01

    A particularly rich region of the electronic spectrum of FeH from 525 to 545 nm was investigated using the techniques of dispersed and undispersed laser-induced fluorescence. Analysis has led to the discovery that several different electronic transitions are embedded in this region; the (0, 0) and (1, 1) bands of the e(6)Pi-a(6)Delta (green) system, the (0, 2) band of the g(6)Phi-X(4)Delta (intercombination) system, the (0, 1) band of the g(6)Phi-a(6)Delta (blue) system, and the (0, 0) band of the g(6)Phi-b(6)Pi system. Seventy-five lines were assigned in the (0, 1) band of the g(6)Phi-a(6)Delta transition. These, with the assignment of an additional 14 lines in the 583 nm region to the (0, 1) band of the e(6)Pi-a(6)Delta transition, led to the extension of the known term values to higher J values for the Omega = 9/2, 7/2, and 5/2 spin components of the v = 1 level of the a(6)Delta state and the novel characterization of the a(6)Delta(3/2) (v = 1) and g(6)Phi(5/2) (v = 0) components. A further 73 lines were assigned to the first four subbands of the (1, 1) band of the e(6)Pi-a(6)Delta transition and term values for the lowest four spin components of the v = 1 level of the e(6)Pi state were determined. This provides the first experimental measurement of a vibrational interval in one of the higher lying electronic states of FeH. The interval does not appear to vary strongly between the spin components (DeltaG(1/2) = 1717, 1713, 1710 cm(-1) for Omega = 7/2, 5/2, 3/2, respectively). Remarkably few of the hot-band transitions assigned in this work could be identified in the complex, high-temperature spectrum of FeH recorded by P. McCormack and S. O'Connor [Astron. Astrophys. Suppl. 26, 373-380 (1976)]. Copyright 1999 Academic Press. PMID:10479583

  8. Teaching of Astronomy: Scenarios of Teaching Practice in Elementary Schools. (Spanish Title: Enseñanza de la Astronomía: Semblanzas de la Práctica Docente en Educación Primaria.) Ensino de Astronomia: Cenários da Prática Docente no Ensino Fundamental

    Science.gov (United States)

    Marchi Gonzatti, Sônia Elisa; Spessatto De Maman, Andréia; Fernandes Borragini, Eliana; Kerber, Júlia Cristina; Haetinger, Werner

    2013-12-01

    atomización de los asuntos, aunque temas como movimientos de la Tierra y fenómenos astronómicos hayan sido citados por la mayoría de los participantes. En cuanto a las estrategias, se verifico que se emplean principalmente clases con el apoyo de recursos bidimensionales, como películas, textos, mapas y búsqueda en internet. Las principales dificultades fueron la falta de formación específica con respecto a los contenidos de Astronomía, y el nivel de abstracción exigido por los contenidos. De modo general, esos indicadores convergen para los resultados ya encontrados en otros estudios, en el que las deficiencias de la formación inicial de los profesores, o incluso su ausencia, dificulta el adecuado abordaje de la Astronomía en las clases. Neste trabalho são apresentados os principais resultados de uma investigação realizada no campo da Educação em Astronomia, com professores do ensino fundamental de duas regiões do Rio Grande do Sul. O objetivo do estudo foi caracterizar o cenário regional do ensino de Astronomia, estabelecendo um comparativo com o cenário nacional. Esse estudo abordou três questões: identificar os principais temas de astronomia trabalhados em sala de aula, as estratégias metodológicas e quais as dificuldades apresentadas pelos professores ao desenvolver sua prática. Quanto aos conteúdos, encontrouse uma pulverização dos assuntos abordados, embora temas como movimentos da Terra e fenômenos astronômicos tenham sido citados pela maioria dos participantes. Sobre estratégias, são utilizadas principalmente aulas com apoio de recursos bidimensionais, como filmes, textos, mapas e pesquisa na internet. As principais dificuldades foram: falta de formação específica em relação a conteúdos de Astronomia; nível de abstração dos conteúdos, que dificultam sua compreensão, tanto pelos alunos quanto pelos próprios professores. De maneira geral, esses indicadores convergem para resultados já encontrados em outros estudos que

  9. The Understanding of Astronomy Concepts by Students from Basic Education of a Public School. (Spanish Title: El Entendimiento de Conceptos de Aastronmía Por Los Alumnos de Educación Básica en Una Escuela Pública.) O Entendimento de Conceitos de Astronomia Por Alunos da Educação Básica: O Caso de Uma Escola Pública Brasileira

    Science.gov (United States)

    Iria Machado, Daniel; dos Santos, Carlos

    2011-07-01

    We present the results obtained in a research on the comprehension of basic astronomical concepts, in which 561 students from fifth grade middle school to third grade high school of a public school of the city of Foz do Iguaçu (Brazil) took part. A test with 20 multiple-choice questions was applied to indentify the most common conceptions expressed by the students. This test was elaborated based on the literature about misconceptions and covered the following topics: the day-night cycle; the time zones; the seasons of the year; the phases of the Moon; the movement of the Moon; the apparent movement of the Sun in the celestial sphere; the eclipses; the dimensions and distances in the Universe; the brightness of the stars and its observation from Earth. Though a small progress was verified in the proportion of scientifically acceptable answers when comparing the eighth grade of middle school to the fifth, and the third grade of high school to the first, there was an overall predominance of alternative conceptions regarding most of the explored subjects, which persisted up to the last year of secondary school. The comparison to data found in this research made in other socio-cultural contexts revealed, in many aspects, similar notions and difficulties revealed by the students. Se presentan los resultados de una investigación sobre la comprensión de conceptos astronómicos básicos, en la cual participaron 561 estudiantes que cursaban entre el quinto grado de la enseñanza primaria y el tercer año de la enseñanza secundaria de una escuela pública de la ciudad de Foz do Iguaçu (Brasil). Se utilizó un test de 20 preguntas de opción múltiple para identificar las concepciones más comunes expresadas por los estudiantes. Este instrumento de recolección de datos se desarrolló en base a la literatura sobre las concepciones alternativas y trató los siguientes temas: el ciclo día-noche, los husos horarios, las estaciones del año, las fases de la Luna, el

  10. Disciplines and Professors of Astronomy in Undergraduate Physics Teachers Formation Courses in Brazilian Universities. (Spanish Title: Disciplinas y Profesores de Astronomia en los Cursos de Licenciatura en Física en Las Universidades Brasileñas.) Disciplinas e Professores de Astronomia Nos Cursos de Licenciatura em Física das Universidades Brasileiras

    Science.gov (United States)

    Roberto, Artur Justiniano, Jr.; Reis, Thiago Henrique; dos Reis Germinaro, Daniel

    2014-12-01

    This article is the result of a research on basic training in Astronomy in physics degrees that performed the ENADE 2011 national examination. The objective was to identify whether there are disciplines of Astronomy in these courses, whether are mandatory or optional, its workload and when it is offered. The relationship between astronomers, physics degrees and disciplines of Astronomy was investigated. To perform this research we examined the results of ENADE 2011 and also the census of Brazilian Astronomical Society. As a result it is observed that in only 15% of the courses there is a mandatory subject of Astronomy, and therefore there is a high probability that 85% of physics teachers trained in 2011 have not had any discipline of Astronomy during their graduation. In addition, the data collected in this study shows a low number of members of SAB (Sociedade Astronômica Brasileira) among the surveyed courses. We have verified that the presence of astronomers in a given university does not imply to have a mandatory discipline of Astronomy in physics degrees at the same university. Este artículo es el resultado de una investigación sobre la formación básica en Astronomía en los cursos de Profesorado en Física que hicieron el examen nacional ENADE 2011. El objetivo del trabajo fue identificar se existen disciplinas de Astronomía en estos cursos, si son obligatorias u optativas, cuál es su carga horaria y el semestre en que son ofrecidas. Se investigó también la correlación entre astrónomos, los cursos de licenciatura en Física y las disciplinas de Astronomía. Para realizar esta investigación se utilizaron los datos del ENADE 2011 y también del censo de la Astronomía brasileña. Como resultado, se observó que en solo 15% de los cursos existe una disciplina obligatoria de Astronomía y que existe una grande probabilidad de que 85% de los profesores de Física formados en el año de 2011 no hayan cursado ninguna disciplina de Astronomía durante su

  11. The Understanding of Astronomy Concepts by Students from Basic Education of a Public School. (Spanish Title: El Entendimiento de Conceptos de Aastronmía Por Los Alumnos de Educación Básica en Una Escuela Pública.) O Entendimento de Conceitos de Astronomia Por Alunos da Educação Básica: O Caso de Uma Escola Pública Brasileira

    Science.gov (United States)

    Iria Machado, Daniel; dos Santos, Carlos

    2011-07-01

    We present the results obtained in a research on the comprehension of basic astronomical concepts, in which 561 students from fifth grade middle school to third grade high school of a public school of the city of Foz do Iguaçu (Brazil) took part. A test with 20 multiple-choice questions was applied to indentify the most common conceptions expressed by the students. This test was elaborated based on the literature about misconceptions and covered the following topics: the day-night cycle; the time zones; the seasons of the year; the phases of the Moon; the movement of the Moon; the apparent movement of the Sun in the celestial sphere; the eclipses; the dimensions and distances in the Universe; the brightness of the stars and its observation from Earth. Though a small progress was verified in the proportion of scientifically acceptable answers when comparing the eighth grade of middle school to the fifth, and the third grade of high school to the first, there was an overall predominance of alternative conceptions regarding most of the explored subjects, which persisted up to the last year of secondary school. The comparison to data found in this research made in other socio-cultural contexts revealed, in many aspects, similar notions and difficulties revealed by the students. Se presentan los resultados de una investigación sobre la comprensión de conceptos astronómicos básicos, en la cual participaron 561 estudiantes que cursaban entre el quinto grado de la enseñanza primaria y el tercer año de la enseñanza secundaria de una escuela pública de la ciudad de Foz do Iguaçu (Brasil). Se utilizó un test de 20 preguntas de opción múltiple para identificar las concepciones más comunes expresadas por los estudiantes. Este instrumento de recolección de datos se desarrolló en base a la literatura sobre las concepciones alternativas y trató los siguientes temas: el ciclo día-noche, los husos horarios, las estaciones del año, las fases de la Luna, el

  12. Development of Educational Resources to Include the Teaching of Astronomy in the First Years of the Basic Education. (Spanish Title: Desarrollo de Recursos Pedagógicos Para Incluir la Enseñanza de la Astronomía en los Primeros Años de la Educación Básica.) Desenvolvimento de Recursos Pedagógicos Para Inserir o Ensino de Astronomia nas Séries Iniciais do Ensino Fundamental

    Science.gov (United States)

    da Silva Morett, Samara; de Oliveira Souza, Marcelo

    2010-07-01

    ía y la vida cotidiana de los estudiantes. La inclusión de la astronomía en la escuela primaria es una manera de demostrar a los estudiantes cómo este campo está presente de forma activa en su vida cotidiana. Las clases que participan en el proyecto participaron en un estudio con el objetivo de proporcionar información a los conocimientos previos que tenían sobre los temas de la astronomía que se examinaron durante el proyecto. Con los experimentos realizados, y la ayuda de las nuevas tecnologías, conceptos astronómicos fueron presentados a los estudiantes de 4to y 5to año de la educación básica de una escuela municipal de Campos dos Goytacazes (RJ). Después de las presentaciones nuevos datos fueran colectados y se han llevado a cabo con el fin de verificar el nivel de aprendizaje alcanzado y se observó que el método utilizado fue una herramienta importante para ayudar al proceso de enseñanza y aprendizaje. El proyecto logró resultados satisfactorios. Neste trabalho será apresentado o desenvolvimento de recursos pedagógicos para a apresentação de conceitos de astronomia nas séries iniciais do ensino fundamental. Este material é composto por apresentações realizadas com o uso de novos recursos tecnológicos, pela fabricação de experimentos e a discussão de curiosidades relativas a esta área de conhecimento. Os experimentos foram construídos com material de baixo custo com o objetivo de permitir que os alunos envolvidos pudessem refazê-los em outras ocasiões. O material apresentado busca enfatizar a relação entre a astronomia e o cotidiano dos alunos. A inclusão da astronomia no ensino fundamental e uma forma de demonstrar aoestudante como esta área está presente de forma ativa em seu cotidiano. As turmas envolvidas no projeto participaram de uma pesquisa com o objetivo de obter dados relativos ao conhecimento prévio que possuíam sobre os tópicos de astronomia que foram considerados no decorrer do projeto. Com os experimentos

  13. Fourth order accurate compact scheme with group velocity control (GVC)

    Institute of Scientific and Technical Information of China (English)

    MA; Yanwen

    2001-01-01

    [1]Kristian, J. , Sandage, A. R. , Westphal, J., The extension of the Hubble diagram: Ⅱ. New redshifts and photometry of very distant galaxy clusters, Astrophys. J., 1978, 221: 383.[2]Sandage, A., The redshift-distant relation V. Galaxy co lors as functions of galactic latitude and redshift, Astrophys, J.,1973, 183: 711.[3]Qu, Q. Y., Qin, Z. H., Han, C. S. et al., A relation between magnitudes and redshifts of QSOs with strong interplanetary scientillation, Chinese Astron., 1979, 4: 97.[4]Tinsley, B. M. , The Galaxy counts, color-redshift relation, and related quantities as probes of cosmology and galactic evolu-tion, Astrophys. J., 1977, 211: 621.[5]Spinrad, H., Djorgovski, S., The status of the Hubble diagram in 1986 (eds. Hewitt, A. Burbidge, G. Fang, L. Z. ),Proc. IAU Symp 124 on Observational Cosmology, New York: D. Reidel Publishing Company, 1986, 129.[6]Fang, L. Z., Zhou, Y. Y., Cheng F. Z. et al., Evolution of quasars with resolved components and determination of decel-eration parameter q0, Scientia Sinica, 1979, 22: 1292.[7]Cheng, K. S., Fan, J. H., Li, Y. et al., Do γ-ray burst associated with metal-rich quasars (ed. Cheng, K. S., Singh,H. P.), Proc. of The Pacific Rim Conference on Stellar Astrophysics, August 13-16, 1997, Houg Kong, 1997.[8]Davis, M., Geller, M. J., Huchra, J., The local mean mass density of the universe: new methods for studying galaxy clus-tering, Astrophys. J., 1978, 221: 1.[9]Gott, J. R., Turner, E. L., The mean luminosity and mass densities in the universe, Astrophys. J., 1976, 209: 1.[10]Shapiro, S. L., The density of matter in the form of galaxies, Astron. J., 1971, 76: 291.[11]Fang, L. Z., Hu, F. X., The large-scale inhomogeneities in the universe (eds. Yang, J., Zhu, C. S. ), Proceeding of A-cademia Sinica--Max-Plank Socity Workshop on High Energy Astrophyics Held in Nanjing, China, April 9-17, 1982,New York: Gordon and Breach Science Publishers S.A. 1982, 425[12]Baldwin, J. A

  14. Preparation and optical properties of GaSb nanoparticles embedded in SiO2 composite films

    Institute of Scientific and Technical Information of China (English)

    LIU; Famin

    2001-01-01

    [1]Kristian, J. , Sandage, A. R. , Westphal, J., The extension of the Hubble diagram: Ⅱ. New redshifts and photometry of very distant galaxy clusters, Astrophys. J., 1978, 221: 383.[2]Sandage, A., The redshift-distant relation V. Galaxy co lors as functions of galactic latitude and redshift, Astrophys, J.,1973, 183: 711.[3]Qu, Q. Y., Qin, Z. H., Han, C. S. et al., A relation between magnitudes and redshifts of QSOs with strong interplanetary scientillation, Chinese Astron., 1979, 4: 97.[4]Tinsley, B. M. , The Galaxy counts, color-redshift relation, and related quantities as probes of cosmology and galactic evolu-tion, Astrophys. J., 1977, 211: 621.[5]Spinrad, H., Djorgovski, S., The status of the Hubble diagram in 1986 (eds. Hewitt, A. Burbidge, G. Fang, L. Z. ),Proc. IAU Symp 124 on Observational Cosmology, New York: D. Reidel Publishing Company, 1986, 129.[6]Fang, L. Z., Zhou, Y. Y., Cheng F. Z. et al., Evolution of quasars with resolved components and determination of decel-eration parameter q0, Scientia Sinica, 1979, 22: 1292.[7]Cheng, K. S., Fan, J. H., Li, Y. et al., Do γ-ray burst associated with metal-rich quasars (ed. Cheng, K. S., Singh,H. P.), Proc. of The Pacific Rim Conference on Stellar Astrophysics, August 13-16, 1997, Houg Kong, 1997.[8]Davis, M., Geller, M. J., Huchra, J., The local mean mass density of the universe: new methods for studying galaxy clus-tering, Astrophys. J., 1978, 221: 1.[9]Gott, J. R., Turner, E. L., The mean luminosity and mass densities in the universe, Astrophys. J., 1976, 209: 1.[10]Shapiro, S. L., The density of matter in the form of galaxies, Astron. J., 1971, 76: 291.[11]Fang, L. Z., Hu, F. X., The large-scale inhomogeneities in the universe (eds. Yang, J., Zhu, C. S. ), Proceeding of A-cademia Sinica--Max-Plank Socity Workshop on High Energy Astrophyics Held in Nanjing, China, April 9-17, 1982,New York: Gordon and Breach Science Publishers S.A. 1982, 425[12]Baldwin, J. A

  15. Pseudo almost periodic solutions for the systems of differential equations with piecewise constant argument

    Institute of Scientific and Technical Information of China (English)

    PIAO; Daxiong

    2001-01-01

    [1]Kristian, J. , Sandage, A. R. , Westphal, J., The extension of the Hubble diagram: Ⅱ. New redshifts and photometry of very distant galaxy clusters, Astrophys. J., 1978, 221: 383.[2]Sandage, A., The redshift-distant relation V. Galaxy co lors as functions of galactic latitude and redshift, Astrophys, J.,1973, 183: 711.[3]Qu, Q. Y., Qin, Z. H., Han, C. S. et al., A relation between magnitudes and redshifts of QSOs with strong interplanetary scientillation, Chinese Astron., 1979, 4: 97.[4]Tinsley, B. M. , The Galaxy counts, color-redshift relation, and related quantities as probes of cosmology and galactic evolu-tion, Astrophys. J., 1977, 211: 621.[5]Spinrad, H., Djorgovski, S., The status of the Hubble diagram in 1986 (eds. Hewitt, A. Burbidge, G. Fang, L. Z. ),Proc. IAU Symp 124 on Observational Cosmology, New York: D. Reidel Publishing Company, 1986, 129.[6]Fang, L. Z., Zhou, Y. Y., Cheng F. Z. et al., Evolution of quasars with resolved components and determination of decel-eration parameter q0, Scientia Sinica, 1979, 22: 1292.[7]Cheng, K. S., Fan, J. H., Li, Y. et al., Do γ-ray burst associated with metal-rich quasars (ed. Cheng, K. S., Singh,H. P.), Proc. of The Pacific Rim Conference on Stellar Astrophysics, August 13-16, 1997, Houg Kong, 1997.[8]Davis, M., Geller, M. J., Huchra, J., The local mean mass density of the universe: new methods for studying galaxy clus-tering, Astrophys. J., 1978, 221: 1.[9]Gott, J. R., Turner, E. L., The mean luminosity and mass densities in the universe, Astrophys. J., 1976, 209: 1.[10]Shapiro, S. L., The density of matter in the form of galaxies, Astron. J., 1971, 76: 291.[11]Fang, L. Z., Hu, F. X., The large-scale inhomogeneities in the universe (eds. Yang, J., Zhu, C. S. ), Proceeding of A-cademia Sinica--Max-Plank Socity Workshop on High Energy Astrophyics Held in Nanjing, China, April 9-17, 1982,New York: Gordon and Breach Science Publishers S.A. 1982, 425[12]Baldwin, J. A

  16. Polynomial solutions of quasi_homogeneous partial differential equations

    Institute of Scientific and Technical Information of China (English)

    LUO; Xuebo

    2001-01-01

    [1]Kristian, J. , Sandage, A. R. , Westphal, J., The extension of the Hubble diagram: Ⅱ. New redshifts and photometry of very distant galaxy clusters, Astrophys. J., 1978, 221: 383.[2]Sandage, A., The redshift-distant relation V. Galaxy co lors as functions of galactic latitude and redshift, Astrophys, J.,1973, 183: 711.[3]Qu, Q. Y., Qin, Z. H., Han, C. S. et al., A relation between magnitudes and redshifts of QSOs with strong interplanetary scientillation, Chinese Astron., 1979, 4: 97.[4]Tinsley, B. M. , The Galaxy counts, color-redshift relation, and related quantities as probes of cosmology and galactic evolu-tion, Astrophys. J., 1977, 211: 621.[5]Spinrad, H., Djorgovski, S., The status of the Hubble diagram in 1986 (eds. Hewitt, A. Burbidge, G. Fang, L. Z. ),Proc. IAU Symp 124 on Observational Cosmology, New York: D. Reidel Publishing Company, 1986, 129.[6]Fang, L. Z., Zhou, Y. Y., Cheng F. Z. et al., Evolution of quasars with resolved components and determination of decel-eration parameter q0, Scientia Sinica, 1979, 22: 1292.[7]Cheng, K. S., Fan, J. H., Li, Y. et al., Do γ-ray burst associated with metal-rich quasars (ed. Cheng, K. S., Singh,H. P.), Proc. of The Pacific Rim Conference on Stellar Astrophysics, August 13-16, 1997, Houg Kong, 1997.[8]Davis, M., Geller, M. J., Huchra, J., The local mean mass density of the universe: new methods for studying galaxy clus-tering, Astrophys. J., 1978, 221: 1.[9]Gott, J. R., Turner, E. L., The mean luminosity and mass densities in the universe, Astrophys. J., 1976, 209: 1.[10]Shapiro, S. L., The density of matter in the form of galaxies, Astron. J., 1971, 76: 291.[11]Fang, L. Z., Hu, F. X., The large-scale inhomogeneities in the universe (eds. Yang, J., Zhu, C. S. ), Proceeding of A-cademia Sinica--Max-Plank Socity Workshop on High Energy Astrophyics Held in Nanjing, China, April 9-17, 1982,New York: Gordon and Breach Science Publishers S.A. 1982, 425[12]Baldwin, J. A

  17. Formation and construction of shock for psystem

    Institute of Scientific and Technical Information of China (English)

    CHEN; Shuxing

    2001-01-01

    [1]Kristian, J. , Sandage, A. R. , Westphal, J., The extension of the Hubble diagram: Ⅱ. New redshifts and photometry of very distant galaxy clusters, Astrophys. J., 1978, 221: 383.[2]Sandage, A., The redshift-distant relation V. Galaxy co lors as functions of galactic latitude and redshift, Astrophys, J.,1973, 183: 711.[3]Qu, Q. Y., Qin, Z. H., Han, C. S. et al., A relation between magnitudes and redshifts of QSOs with strong interplanetary scientillation, Chinese Astron., 1979, 4: 97.[4]Tinsley, B. M. , The Galaxy counts, color-redshift relation, and related quantities as probes of cosmology and galactic evolu-tion, Astrophys. J., 1977, 211: 621.[5]Spinrad, H., Djorgovski, S., The status of the Hubble diagram in 1986 (eds. Hewitt, A. Burbidge, G. Fang, L. Z. ),Proc. IAU Symp 124 on Observational Cosmology, New York: D. Reidel Publishing Company, 1986, 129.[6]Fang, L. Z., Zhou, Y. Y., Cheng F. Z. et al., Evolution of quasars with resolved components and determination of decel-eration parameter q0, Scientia Sinica, 1979, 22: 1292.[7]Cheng, K. S., Fan, J. H., Li, Y. et al., Do γ-ray burst associated with metal-rich quasars (ed. Cheng, K. S., Singh,H. P.), Proc. of The Pacific Rim Conference on Stellar Astrophysics, August 13-16, 1997, Houg Kong, 1997.[8]Davis, M., Geller, M. J., Huchra, J., The local mean mass density of the universe: new methods for studying galaxy clus-tering, Astrophys. J., 1978, 221: 1.[9]Gott, J. R., Turner, E. L., The mean luminosity and mass densities in the universe, Astrophys. J., 1976, 209: 1.[10]Shapiro, S. L., The density of matter in the form of galaxies, Astron. J., 1971, 76: 291.[11]Fang, L. Z., Hu, F. X., The large-scale inhomogeneities in the universe (eds. Yang, J., Zhu, C. S. ), Proceeding of A-cademia Sinica--Max-Plank Socity Workshop on High Energy Astrophyics Held in Nanjing, China, April 9-17, 1982,New York: Gordon and Breach Science Publishers S.A. 1982, 425[12]Baldwin, J. A

  18. Molecular lines and continuum from W51A (I)

    Institute of Scientific and Technical Information of China (English)

    PEI; Chunchuan

    2001-01-01

    [1]Kristian, J. , Sandage, A. R. , Westphal, J., The extension of the Hubble diagram: Ⅱ. New redshifts and photometry of very distant galaxy clusters, Astrophys. J., 1978, 221: 383.[2]Sandage, A., The redshift-distant relation V. Galaxy co lors as functions of galactic latitude and redshift, Astrophys, J.,1973, 183: 711.[3]Qu, Q. Y., Qin, Z. H., Han, C. S. et al., A relation between magnitudes and redshifts of QSOs with strong interplanetary scientillation, Chinese Astron., 1979, 4: 97.[4]Tinsley, B. M. , The Galaxy counts, color-redshift relation, and related quantities as probes of cosmology and galactic evolu-tion, Astrophys. J., 1977, 211: 621.[5]Spinrad, H., Djorgovski, S., The status of the Hubble diagram in 1986 (eds. Hewitt, A. Burbidge, G. Fang, L. Z. ),Proc. IAU Symp 124 on Observational Cosmology, New York: D. Reidel Publishing Company, 1986, 129.[6]Fang, L. Z., Zhou, Y. Y., Cheng F. Z. et al., Evolution of quasars with resolved components and determination of decel-eration parameter q0, Scientia Sinica, 1979, 22: 1292.[7]Cheng, K. S., Fan, J. H., Li, Y. et al., Do γ-ray burst associated with metal-rich quasars (ed. Cheng, K. S., Singh,H. P.), Proc. of The Pacific Rim Conference on Stellar Astrophysics, August 13-16, 1997, Houg Kong, 1997.[8]Davis, M., Geller, M. J., Huchra, J., The local mean mass density of the universe: new methods for studying galaxy clus-tering, Astrophys. J., 1978, 221: 1.[9]Gott, J. R., Turner, E. L., The mean luminosity and mass densities in the universe, Astrophys. J., 1976, 209: 1.[10]Shapiro, S. L., The density of matter in the form of galaxies, Astron. J., 1971, 76: 291.[11]Fang, L. Z., Hu, F. X., The large-scale inhomogeneities in the universe (eds. Yang, J., Zhu, C. S. ), Proceeding of A-cademia Sinica--Max-Plank Socity Workshop on High Energy Astrophyics Held in Nanjing, China, April 9-17, 1982,New York: Gordon and Breach Science Publishers S.A. 1982, 425[12]Baldwin, J. A

  19. A new kind of graded Lie algebra and parastatistical supersymmetry

    Institute of Scientific and Technical Information of China (English)

    YANG; Weimin

    2001-01-01

    [1]Kristian, J. , Sandage, A. R. , Westphal, J., The extension of the Hubble diagram: Ⅱ. New redshifts and photometry of very distant galaxy clusters, Astrophys. J., 1978, 221: 383.[2]Sandage, A., The redshift-distant relation V. Galaxy co lors as functions of galactic latitude and redshift, Astrophys, J.,1973, 183: 711.[3]Qu, Q. Y., Qin, Z. H., Han, C. S. et al., A relation between magnitudes and redshifts of QSOs with strong interplanetary scientillation, Chinese Astron., 1979, 4: 97.[4]Tinsley, B. M. , The Galaxy counts, color-redshift relation, and related quantities as probes of cosmology and galactic evolu-tion, Astrophys. J., 1977, 211: 621.[5]Spinrad, H., Djorgovski, S., The status of the Hubble diagram in 1986 (eds. Hewitt, A. Burbidge, G. Fang, L. Z. ),Proc. IAU Symp 124 on Observational Cosmology, New York: D. Reidel Publishing Company, 1986, 129.[6]Fang, L. Z., Zhou, Y. Y., Cheng F. Z. et al., Evolution of quasars with resolved components and determination of decel-eration parameter q0, Scientia Sinica, 1979, 22: 1292.[7]Cheng, K. S., Fan, J. H., Li, Y. et al., Do γ-ray burst associated with metal-rich quasars (ed. Cheng, K. S., Singh,H. P.), Proc. of The Pacific Rim Conference on Stellar Astrophysics, August 13-16, 1997, Houg Kong, 1997.[8]Davis, M., Geller, M. J., Huchra, J., The local mean mass density of the universe: new methods for studying galaxy clus-tering, Astrophys. J., 1978, 221: 1.[9]Gott, J. R., Turner, E. L., The mean luminosity and mass densities in the universe, Astrophys. J., 1976, 209: 1.[10]Shapiro, S. L., The density of matter in the form of galaxies, Astron. J., 1971, 76: 291.[11]Fang, L. Z., Hu, F. X., The large-scale inhomogeneities in the universe (eds. Yang, J., Zhu, C. S. ), Proceeding of A-cademia Sinica--Max-Plank Socity Workshop on High Energy Astrophyics Held in Nanjing, China, April 9-17, 1982,New York: Gordon and Breach Science Publishers S.A. 1982, 425[12]Baldwin, J. A

  20. The non-interior continuation methods for solving the P0 function nonlinear complementarity problem

    Institute of Scientific and Technical Information of China (English)

    HUANG; Zhenghai

    2001-01-01

    [1]Kristian, J. , Sandage, A. R. , Westphal, J., The extension of the Hubble diagram: Ⅱ. New redshifts and photometry of very distant galaxy clusters, Astrophys. J., 1978, 221: 383.[2]Sandage, A., The redshift-distant relation V. Galaxy co lors as functions of galactic latitude and redshift, Astrophys, J.,1973, 183: 711.[3]Qu, Q. Y., Qin, Z. H., Han, C. S. et al., A relation between magnitudes and redshifts of QSOs with strong interplanetary scientillation, Chinese Astron., 1979, 4: 97.[4]Tinsley, B. M. , The Galaxy counts, color-redshift relation, and related quantities as probes of cosmology and galactic evolu-tion, Astrophys. J., 1977, 211: 621.[5]Spinrad, H., Djorgovski, S., The status of the Hubble diagram in 1986 (eds. Hewitt, A. Burbidge, G. Fang, L. Z. ),Proc. IAU Symp 124 on Observational Cosmology, New York: D. Reidel Publishing Company, 1986, 129.[6]Fang, L. Z., Zhou, Y. Y., Cheng F. Z. et al., Evolution of quasars with resolved components and determination of decel-eration parameter q0, Scientia Sinica, 1979, 22: 1292.[7]Cheng, K. S., Fan, J. H., Li, Y. et al., Do γ-ray burst associated with metal-rich quasars (ed. Cheng, K. S., Singh,H. P.), Proc. of The Pacific Rim Conference on Stellar Astrophysics, August 13-16, 1997, Houg Kong, 1997.[8]Davis, M., Geller, M. J., Huchra, J., The local mean mass density of the universe: new methods for studying galaxy clus-tering, Astrophys. J., 1978, 221: 1.[9]Gott, J. R., Turner, E. L., The mean luminosity and mass densities in the universe, Astrophys. J., 1976, 209: 1.[10]Shapiro, S. L., The density of matter in the form of galaxies, Astron. J., 1971, 76: 291.[11]Fang, L. Z., Hu, F. X., The large-scale inhomogeneities in the universe (eds. Yang, J., Zhu, C. S. ), Proceeding of A-cademia Sinica--Max-Plank Socity Workshop on High Energy Astrophyics Held in Nanjing, China, April 9-17, 1982,New York: Gordon and Breach Science Publishers S.A. 1982, 425[12]Baldwin, J. A

  1. On large increments of a two-parameter fractional Wiener process

    Institute of Scientific and Technical Information of China (English)

    ZHANG; Lixin

    2001-01-01

    [1]Kristian, J. , Sandage, A. R. , Westphal, J., The extension of the Hubble diagram: Ⅱ. New redshifts and photometry of very distant galaxy clusters, Astrophys. J., 1978, 221: 383.[2]Sandage, A., The redshift-distant relation V. Galaxy co lors as functions of galactic latitude and redshift, Astrophys, J.,1973, 183: 711.[3]Qu, Q. Y., Qin, Z. H., Han, C. S. et al., A relation between magnitudes and redshifts of QSOs with strong interplanetary scientillation, Chinese Astron., 1979, 4: 97.[4]Tinsley, B. M. , The Galaxy counts, color-redshift relation, and related quantities as probes of cosmology and galactic evolu-tion, Astrophys. J., 1977, 211: 621.[5]Spinrad, H., Djorgovski, S., The status of the Hubble diagram in 1986 (eds. Hewitt, A. Burbidge, G. Fang, L. Z. ),Proc. IAU Symp 124 on Observational Cosmology, New York: D. Reidel Publishing Company, 1986, 129.[6]Fang, L. Z., Zhou, Y. Y., Cheng F. Z. et al., Evolution of quasars with resolved components and determination of decel-eration parameter q0, Scientia Sinica, 1979, 22: 1292.[7]Cheng, K. S., Fan, J. H., Li, Y. et al., Do γ-ray burst associated with metal-rich quasars (ed. Cheng, K. S., Singh,H. P.), Proc. of The Pacific Rim Conference on Stellar Astrophysics, August 13-16, 1997, Houg Kong, 1997.[8]Davis, M., Geller, M. J., Huchra, J., The local mean mass density of the universe: new methods for studying galaxy clus-tering, Astrophys. J., 1978, 221: 1.[9]Gott, J. R., Turner, E. L., The mean luminosity and mass densities in the universe, Astrophys. J., 1976, 209: 1.[10]Shapiro, S. L., The density of matter in the form of galaxies, Astron. J., 1971, 76: 291.[11]Fang, L. Z., Hu, F. X., The large-scale inhomogeneities in the universe (eds. Yang, J., Zhu, C. S. ), Proceeding of A-cademia Sinica--Max-Plank Socity Workshop on High Energy Astrophyics Held in Nanjing, China, April 9-17, 1982,New York: Gordon and Breach Science Publishers S.A. 1982, 425[12]Baldwin, J. A

  2. The Hubble diagram of metal-rich QSOs and deceleration parameter q0

    Institute of Scientific and Technical Information of China (English)

    XIE; Guangzhong(

    2001-01-01

    [1]Kristian, J. , Sandage, A. R. , Westphal, J., The extension of the Hubble diagram: Ⅱ. New redshifts and photometry of very distant galaxy clusters, Astrophys. J., 1978, 221: 383.[2]Sandage, A., The redshift-distant relation V. Galaxy co lors as functions of galactic latitude and redshift, Astrophys, J.,1973, 183: 711.[3]Qu, Q. Y., Qin, Z. H., Han, C. S. et al., A relation between magnitudes and redshifts of QSOs with strong interplanetary scientillation, Chinese Astron., 1979, 4: 97.[4]Tinsley, B. M. , The Galaxy counts, color-redshift relation, and related quantities as probes of cosmology and galactic evolu-tion, Astrophys. J., 1977, 211: 621.[5]Spinrad, H., Djorgovski, S., The status of the Hubble diagram in 1986 (eds. Hewitt, A. Burbidge, G. Fang, L. Z. ),Proc. IAU Symp 124 on Observational Cosmology, New York: D. Reidel Publishing Company, 1986, 129.[6]Fang, L. Z., Zhou, Y. Y., Cheng F. Z. et al., Evolution of quasars with resolved components and determination of decel-eration parameter q0, Scientia Sinica, 1979, 22: 1292.[7]Cheng, K. S., Fan, J. H., Li, Y. et al., Do γ-ray burst associated with metal-rich quasars (ed. Cheng, K. S., Singh,H. P.), Proc. of The Pacific Rim Conference on Stellar Astrophysics, August 13-16, 1997, Houg Kong, 1997.[8]Davis, M., Geller, M. J., Huchra, J., The local mean mass density of the universe: new methods for studying galaxy clus-tering, Astrophys. J., 1978, 221: 1.[9]Gott, J. R., Turner, E. L., The mean luminosity and mass densities in the universe, Astrophys. J., 1976, 209: 1.[10]Shapiro, S. L., The density of matter in the form of galaxies, Astron. J., 1971, 76: 291.[11]Fang, L. Z., Hu, F. X., The large-scale inhomogeneities in the universe (eds. Yang, J., Zhu, C. S. ), Proceeding of A-cademia Sinica--Max-Plank Socity Workshop on High Energy Astrophyics Held in Nanjing, China, April 9-17, 1982,New York: Gordon and Breach Science Publishers S.A. 1982, 425[12]Baldwin, J. A

  3. The role of Sm ions in optical storage of SrS

    Institute of Scientific and Technical Information of China (English)

    HE; Zhiyi

    2001-01-01

    [1]Kristian, J. , Sandage, A. R. , Westphal, J., The extension of the Hubble diagram: Ⅱ. New redshifts and photometry of very distant galaxy clusters, Astrophys. J., 1978, 221: 383.[2]Sandage, A., The redshift-distant relation V. Galaxy co lors as functions of galactic latitude and redshift, Astrophys, J.,1973, 183: 711.[3]Qu, Q. Y., Qin, Z. H., Han, C. S. et al., A relation between magnitudes and redshifts of QSOs with strong interplanetary scientillation, Chinese Astron., 1979, 4: 97.[4]Tinsley, B. M. , The Galaxy counts, color-redshift relation, and related quantities as probes of cosmology and galactic evolu-tion, Astrophys. J., 1977, 211: 621.[5]Spinrad, H., Djorgovski, S., The status of the Hubble diagram in 1986 (eds. Hewitt, A. Burbidge, G. Fang, L. Z. ),Proc. IAU Symp 124 on Observational Cosmology, New York: D. Reidel Publishing Company, 1986, 129.[6]Fang, L. Z., Zhou, Y. Y., Cheng F. Z. et al., Evolution of quasars with resolved components and determination of decel-eration parameter q0, Scientia Sinica, 1979, 22: 1292.[7]Cheng, K. S., Fan, J. H., Li, Y. et al., Do γ-ray burst associated with metal-rich quasars (ed. Cheng, K. S., Singh,H. P.), Proc. of The Pacific Rim Conference on Stellar Astrophysics, August 13-16, 1997, Houg Kong, 1997.[8]Davis, M., Geller, M. J., Huchra, J., The local mean mass density of the universe: new methods for studying galaxy clus-tering, Astrophys. J., 1978, 221: 1.[9]Gott, J. R., Turner, E. L., The mean luminosity and mass densities in the universe, Astrophys. J., 1976, 209: 1.[10]Shapiro, S. L., The density of matter in the form of galaxies, Astron. J., 1971, 76: 291.[11]Fang, L. Z., Hu, F. X., The large-scale inhomogeneities in the universe (eds. Yang, J., Zhu, C. S. ), Proceeding of A-cademia Sinica--Max-Plank Socity Workshop on High Energy Astrophyics Held in Nanjing, China, April 9-17, 1982,New York: Gordon and Breach Science Publishers S.A. 1982, 425[12]Baldwin, J. A

  4. Existence of shocklets in a two-dimensional supersonic mixing layer and its influence on the flow structure

    Institute of Scientific and Technical Information of China (English)

    CAO; Wei

    2001-01-01

    [1]Kristian, J. , Sandage, A. R. , Westphal, J., The extension of the Hubble diagram: Ⅱ. New redshifts and photometry of very distant galaxy clusters, Astrophys. J., 1978, 221: 383.[2]Sandage, A., The redshift-distant relation V. Galaxy co lors as functions of galactic latitude and redshift, Astrophys, J.,1973, 183: 711.[3]Qu, Q. Y., Qin, Z. H., Han, C. S. et al., A relation between magnitudes and redshifts of QSOs with strong interplanetary scientillation, Chinese Astron., 1979, 4: 97.[4]Tinsley, B. M. , The Galaxy counts, color-redshift relation, and related quantities as probes of cosmology and galactic evolu-tion, Astrophys. J., 1977, 211: 621.[5]Spinrad, H., Djorgovski, S., The status of the Hubble diagram in 1986 (eds. Hewitt, A. Burbidge, G. Fang, L. Z. ),Proc. IAU Symp 124 on Observational Cosmology, New York: D. Reidel Publishing Company, 1986, 129.[6]Fang, L. Z., Zhou, Y. Y., Cheng F. Z. et al., Evolution of quasars with resolved components and determination of decel-eration parameter q0, Scientia Sinica, 1979, 22: 1292.[7]Cheng, K. S., Fan, J. H., Li, Y. et al., Do γ-ray burst associated with metal-rich quasars (ed. Cheng, K. S., Singh,H. P.), Proc. of The Pacific Rim Conference on Stellar Astrophysics, August 13-16, 1997, Houg Kong, 1997.[8]Davis, M., Geller, M. J., Huchra, J., The local mean mass density of the universe: new methods for studying galaxy clus-tering, Astrophys. J., 1978, 221: 1.[9]Gott, J. R., Turner, E. L., The mean luminosity and mass densities in the universe, Astrophys. J., 1976, 209: 1.[10]Shapiro, S. L., The density of matter in the form of galaxies, Astron. J., 1971, 76: 291.[11]Fang, L. Z., Hu, F. X., The large-scale inhomogeneities in the universe (eds. Yang, J., Zhu, C. S. ), Proceeding of A-cademia Sinica--Max-Plank Socity Workshop on High Energy Astrophyics Held in Nanjing, China, April 9-17, 1982,New York: Gordon and Breach Science Publishers S.A. 1982, 425[12]Baldwin, J. A

  5. Extremal hexagonal chains concerning largest eigenvalue

    Institute of Scientific and Technical Information of China (English)

    ZHANG; Lianzhu

    2001-01-01

    [1]Kristian, J. , Sandage, A. R. , Westphal, J., The extension of the Hubble diagram: Ⅱ. New redshifts and photometry of very distant galaxy clusters, Astrophys. J., 1978, 221: 383.[2]Sandage, A., The redshift-distant relation V. Galaxy co lors as functions of galactic latitude and redshift, Astrophys, J.,1973, 183: 711.[3]Qu, Q. Y., Qin, Z. H., Han, C. S. et al., A relation between magnitudes and redshifts of QSOs with strong interplanetary scientillation, Chinese Astron., 1979, 4: 97.[4]Tinsley, B. M. , The Galaxy counts, color-redshift relation, and related quantities as probes of cosmology and galactic evolu-tion, Astrophys. J., 1977, 211: 621.[5]Spinrad, H., Djorgovski, S., The status of the Hubble diagram in 1986 (eds. Hewitt, A. Burbidge, G. Fang, L. Z. ),Proc. IAU Symp 124 on Observational Cosmology, New York: D. Reidel Publishing Company, 1986, 129.[6]Fang, L. Z., Zhou, Y. Y., Cheng F. Z. et al., Evolution of quasars with resolved components and determination of decel-eration parameter q0, Scientia Sinica, 1979, 22: 1292.[7]Cheng, K. S., Fan, J. H., Li, Y. et al., Do γ-ray burst associated with metal-rich quasars (ed. Cheng, K. S., Singh,H. P.), Proc. of The Pacific Rim Conference on Stellar Astrophysics, August 13-16, 1997, Houg Kong, 1997.[8]Davis, M., Geller, M. J., Huchra, J., The local mean mass density of the universe: new methods for studying galaxy clus-tering, Astrophys. J., 1978, 221: 1.[9]Gott, J. R., Turner, E. L., The mean luminosity and mass densities in the universe, Astrophys. J., 1976, 209: 1.[10]Shapiro, S. L., The density of matter in the form of galaxies, Astron. J., 1971, 76: 291.[11]Fang, L. Z., Hu, F. X., The large-scale inhomogeneities in the universe (eds. Yang, J., Zhu, C. S. ), Proceeding of A-cademia Sinica--Max-Plank Socity Workshop on High Energy Astrophyics Held in Nanjing, China, April 9-17, 1982,New York: Gordon and Breach Science Publishers S.A. 1982, 425[12]Baldwin, J. A

  6. Generalized ergodicity

    Institute of Scientific and Technical Information of China (English)

    ZHENG; Zuohuan

    2001-01-01

    [1]Kristian, J. , Sandage, A. R. , Westphal, J., The extension of the Hubble diagram: Ⅱ. New redshifts and photometry of very distant galaxy clusters, Astrophys. J., 1978, 221: 383.[2]Sandage, A., The redshift-distant relation V. Galaxy co lors as functions of galactic latitude and redshift, Astrophys, J.,1973, 183: 711.[3]Qu, Q. Y., Qin, Z. H., Han, C. S. et al., A relation between magnitudes and redshifts of QSOs with strong interplanetary scientillation, Chinese Astron., 1979, 4: 97.[4]Tinsley, B. M. , The Galaxy counts, color-redshift relation, and related quantities as probes of cosmology and galactic evolu-tion, Astrophys. J., 1977, 211: 621.[5]Spinrad, H., Djorgovski, S., The status of the Hubble diagram in 1986 (eds. Hewitt, A. Burbidge, G. Fang, L. Z. ),Proc. IAU Symp 124 on Observational Cosmology, New York: D. Reidel Publishing Company, 1986, 129.[6]Fang, L. Z., Zhou, Y. Y., Cheng F. Z. et al., Evolution of quasars with resolved components and determination of decel-eration parameter q0, Scientia Sinica, 1979, 22: 1292.[7]Cheng, K. S., Fan, J. H., Li, Y. et al., Do γ-ray burst associated with metal-rich quasars (ed. Cheng, K. S., Singh,H. P.), Proc. of The Pacific Rim Conference on Stellar Astrophysics, August 13-16, 1997, Houg Kong, 1997.[8]Davis, M., Geller, M. J., Huchra, J., The local mean mass density of the universe: new methods for studying galaxy clus-tering, Astrophys. J., 1978, 221: 1.[9]Gott, J. R., Turner, E. L., The mean luminosity and mass densities in the universe, Astrophys. J., 1976, 209: 1.[10]Shapiro, S. L., The density of matter in the form of galaxies, Astron. J., 1971, 76: 291.[11]Fang, L. Z., Hu, F. X., The large-scale inhomogeneities in the universe (eds. Yang, J., Zhu, C. S. ), Proceeding of A-cademia Sinica--Max-Plank Socity Workshop on High Energy Astrophyics Held in Nanjing, China, April 9-17, 1982,New York: Gordon and Breach Science Publishers S.A. 1982, 425[12]Baldwin, J. A

  7. Recovery of band limited functions via cardinal splines

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    [1]Kristian, J. , Sandage, A. R. , Westphal, J., The extension of the Hubble diagram: Ⅱ. New redshifts and photometry of very distant galaxy clusters, Astrophys. J., 1978, 221: 383.[2]Sandage, A., The redshift-distant relation V. Galaxy co lors as functions of galactic latitude and redshift, Astrophys, J.,1973, 183: 711.[3]Qu, Q. Y., Qin, Z. H., Han, C. S. et al., A relation between magnitudes and redshifts of QSOs with strong interplanetary scientillation, Chinese Astron., 1979, 4: 97.[4]Tinsley, B. M. , The Galaxy counts, color-redshift relation, and related quantities as probes of cosmology and galactic evolu-tion, Astrophys. J., 1977, 211: 621.[5]Spinrad, H., Djorgovski, S., The status of the Hubble diagram in 1986 (eds. Hewitt, A. Burbidge, G. Fang, L. Z. ),Proc. IAU Symp 124 on Observational Cosmology, New York: D. Reidel Publishing Company, 1986, 129.[6]Fang, L. Z., Zhou, Y. Y., Cheng F. Z. et al., Evolution of quasars with resolved components and determination of decel-eration parameter q0, Scientia Sinica, 1979, 22: 1292.[7]Cheng, K. S., Fan, J. H., Li, Y. et al., Do γ-ray burst associated with metal-rich quasars (ed. Cheng, K. S., Singh,H. P.), Proc. of The Pacific Rim Conference on Stellar Astrophysics, August 13-16, 1997, Houg Kong, 1997.[8]Davis, M., Geller, M. J., Huchra, J., The local mean mass density of the universe: new methods for studying galaxy clus-tering, Astrophys. J., 1978, 221: 1.[9]Gott, J. R., Turner, E. L., The mean luminosity and mass densities in the universe, Astrophys. J., 1976, 209: 1.[10]Shapiro, S. L., The density of matter in the form of galaxies, Astron. J., 1971, 76: 291.[11]Fang, L. Z., Hu, F. X., The large-scale inhomogeneities in the universe (eds. Yang, J., Zhu, C. S. ), Proceeding of A-cademia Sinica--Max-Plank Socity Workshop on High Energy Astrophyics Held in Nanjing, China, April 9-17, 1982,New York: Gordon and Breach Science Publishers S.A. 1982, 425[12]Baldwin, J. A

  8. Electronic structure of ZnO and its defects

    Institute of Scientific and Technical Information of China (English)

    XU; Pengshou

    2001-01-01

    [1]Kristian, J. , Sandage, A. R. , Westphal, J., The extension of the Hubble diagram: Ⅱ. New redshifts and photometry of very distant galaxy clusters, Astrophys. J., 1978, 221: 383.[2]Sandage, A., The redshift-distant relation V. Galaxy co lors as functions of galactic latitude and redshift, Astrophys, J.,1973, 183: 711.[3]Qu, Q. Y., Qin, Z. H., Han, C. S. et al., A relation between magnitudes and redshifts of QSOs with strong interplanetary scientillation, Chinese Astron., 1979, 4: 97.[4]Tinsley, B. M. , The Galaxy counts, color-redshift relation, and related quantities as probes of cosmology and galactic evolu-tion, Astrophys. J., 1977, 211: 621.[5]Spinrad, H., Djorgovski, S., The status of the Hubble diagram in 1986 (eds. Hewitt, A. Burbidge, G. Fang, L. Z. ),Proc. IAU Symp 124 on Observational Cosmology, New York: D. Reidel Publishing Company, 1986, 129.[6]Fang, L. Z., Zhou, Y. Y., Cheng F. Z. et al., Evolution of quasars with resolved components and determination of decel-eration parameter q0, Scientia Sinica, 1979, 22: 1292.[7]Cheng, K. S., Fan, J. H., Li, Y. et al., Do γ-ray burst associated with metal-rich quasars (ed. Cheng, K. S., Singh,H. P.), Proc. of The Pacific Rim Conference on Stellar Astrophysics, August 13-16, 1997, Houg Kong, 1997.[8]Davis, M., Geller, M. J., Huchra, J., The local mean mass density of the universe: new methods for studying galaxy clus-tering, Astrophys. J., 1978, 221: 1.[9]Gott, J. R., Turner, E. L., The mean luminosity and mass densities in the universe, Astrophys. J., 1976, 209: 1.[10]Shapiro, S. L., The density of matter in the form of galaxies, Astron. J., 1971, 76: 291.[11]Fang, L. Z., Hu, F. X., The large-scale inhomogeneities in the universe (eds. Yang, J., Zhu, C. S. ), Proceeding of A-cademia Sinica--Max-Plank Socity Workshop on High Energy Astrophyics Held in Nanjing, China, April 9-17, 1982,New York: Gordon and Breach Science Publishers S.A. 1982, 425[12]Baldwin, J. A

  9. Effect of Mg and C contents in MgCNi3, and structure and superconductivity of MgCNi3-xCox

    Institute of Scientific and Technical Information of China (English)

    REN; Zhi'an

    2001-01-01

    [1]Kristian, J. , Sandage, A. R. , Westphal, J., The extension of the Hubble diagram: Ⅱ. New redshifts and photometry of very distant galaxy clusters, Astrophys. J., 1978, 221: 383.[2]Sandage, A., The redshift-distant relation V. Galaxy co lors as functions of galactic latitude and redshift, Astrophys, J.,1973, 183: 711.[3]Qu, Q. Y., Qin, Z. H., Han, C. S. et al., A relation between magnitudes and redshifts of QSOs with strong interplanetary scientillation, Chinese Astron., 1979, 4: 97.[4]Tinsley, B. M. , The Galaxy counts, color-redshift relation, and related quantities as probes of cosmology and galactic evolu-tion, Astrophys. J., 1977, 211: 621.[5]Spinrad, H., Djorgovski, S., The status of the Hubble diagram in 1986 (eds. Hewitt, A. Burbidge, G. Fang, L. Z. ),Proc. IAU Symp 124 on Observational Cosmology, New York: D. Reidel Publishing Company, 1986, 129.[6]Fang, L. Z., Zhou, Y. Y., Cheng F. Z. et al., Evolution of quasars with resolved components and determination of decel-eration parameter q0, Scientia Sinica, 1979, 22: 1292.[7]Cheng, K. S., Fan, J. H., Li, Y. et al., Do γ-ray burst associated with metal-rich quasars (ed. Cheng, K. S., Singh,H. P.), Proc. of The Pacific Rim Conference on Stellar Astrophysics, August 13-16, 1997, Houg Kong, 1997.[8]Davis, M., Geller, M. J., Huchra, J., The local mean mass density of the universe: new methods for studying galaxy clus-tering, Astrophys. J., 1978, 221: 1.[9]Gott, J. R., Turner, E. L., The mean luminosity and mass densities in the universe, Astrophys. J., 1976, 209: 1.[10]Shapiro, S. L., The density of matter in the form of galaxies, Astron. J., 1971, 76: 291.[11]Fang, L. Z., Hu, F. X., The large-scale inhomogeneities in the universe (eds. Yang, J., Zhu, C. S. ), Proceeding of A-cademia Sinica--Max-Plank Socity Workshop on High Energy Astrophyics Held in Nanjing, China, April 9-17, 1982,New York: Gordon and Breach Science Publishers S.A. 1982, 425[12]Baldwin, J. A

  10. Analysis of astronomical records of King Wu's Conquest

    Institute of Scientific and Technical Information of China (English)

    LIU; Ciyuan

    2001-01-01

    [1]Kristian, J. , Sandage, A. R. , Westphal, J., The extension of the Hubble diagram: Ⅱ. New redshifts and photometry of very distant galaxy clusters, Astrophys. J., 1978, 221: 383.[2]Sandage, A., The redshift-distant relation V. Galaxy co lors as functions of galactic latitude and redshift, Astrophys, J.,1973, 183: 711.[3]Qu, Q. Y., Qin, Z. H., Han, C. S. et al., A relation between magnitudes and redshifts of QSOs with strong interplanetary scientillation, Chinese Astron., 1979, 4: 97.[4]Tinsley, B. M. , The Galaxy counts, color-redshift relation, and related quantities as probes of cosmology and galactic evolu-tion, Astrophys. J., 1977, 211: 621.[5]Spinrad, H., Djorgovski, S., The status of the Hubble diagram in 1986 (eds. Hewitt, A. Burbidge, G. Fang, L. Z. ),Proc. IAU Symp 124 on Observational Cosmology, New York: D. Reidel Publishing Company, 1986, 129.[6]Fang, L. Z., Zhou, Y. Y., Cheng F. Z. et al., Evolution of quasars with resolved components and determination of decel-eration parameter q0, Scientia Sinica, 1979, 22: 1292.[7]Cheng, K. S., Fan, J. H., Li, Y. et al., Do γ-ray burst associated with metal-rich quasars (ed. Cheng, K. S., Singh,H. P.), Proc. of The Pacific Rim Conference on Stellar Astrophysics, August 13-16, 1997, Houg Kong, 1997.[8]Davis, M., Geller, M. J., Huchra, J., The local mean mass density of the universe: new methods for studying galaxy clus-tering, Astrophys. J., 1978, 221: 1.[9]Gott, J. R., Turner, E. L., The mean luminosity and mass densities in the universe, Astrophys. J., 1976, 209: 1.[10]Shapiro, S. L., The density of matter in the form of galaxies, Astron. J., 1971, 76: 291.[11]Fang, L. Z., Hu, F. X., The large-scale inhomogeneities in the universe (eds. Yang, J., Zhu, C. S. ), Proceeding of A-cademia Sinica--Max-Plank Socity Workshop on High Energy Astrophyics Held in Nanjing, China, April 9-17, 1982,New York: Gordon and Breach Science Publishers S.A. 1982, 425[12]Baldwin, J. A

  11. Kronecker limit formula for real quadratic number fields(III)

    Institute of Scientific and Technical Information of China (English)

    LU; Hongwen

    2001-01-01

    [1]Kristian, J. , Sandage, A. R. , Westphal, J., The extension of the Hubble diagram: Ⅱ. New redshifts and photometry of very distant galaxy clusters, Astrophys. J., 1978, 221: 383.[2]Sandage, A., The redshift-distant relation V. Galaxy co lors as functions of galactic latitude and redshift, Astrophys, J.,1973, 183: 711.[3]Qu, Q. Y., Qin, Z. H., Han, C. S. et al., A relation between magnitudes and redshifts of QSOs with strong interplanetary scientillation, Chinese Astron., 1979, 4: 97.[4]Tinsley, B. M. , The Galaxy counts, color-redshift relation, and related quantities as probes of cosmology and galactic evolu-tion, Astrophys. J., 1977, 211: 621.[5]Spinrad, H., Djorgovski, S., The status of the Hubble diagram in 1986 (eds. Hewitt, A. Burbidge, G. Fang, L. Z. ),Proc. IAU Symp 124 on Observational Cosmology, New York: D. Reidel Publishing Company, 1986, 129.[6]Fang, L. Z., Zhou, Y. Y., Cheng F. Z. et al., Evolution of quasars with resolved components and determination of decel-eration parameter q0, Scientia Sinica, 1979, 22: 1292.[7]Cheng, K. S., Fan, J. H., Li, Y. et al., Do γ-ray burst associated with metal-rich quasars (ed. Cheng, K. S., Singh,H. P.), Proc. of The Pacific Rim Conference on Stellar Astrophysics, August 13-16, 1997, Houg Kong, 1997.[8]Davis, M., Geller, M. J., Huchra, J., The local mean mass density of the universe: new methods for studying galaxy clus-tering, Astrophys. J., 1978, 221: 1.[9]Gott, J. R., Turner, E. L., The mean luminosity and mass densities in the universe, Astrophys. J., 1976, 209: 1.[10]Shapiro, S. L., The density of matter in the form of galaxies, Astron. J., 1971, 76: 291.[11]Fang, L. Z., Hu, F. X., The large-scale inhomogeneities in the universe (eds. Yang, J., Zhu, C. S. ), Proceeding of A-cademia Sinica--Max-Plank Socity Workshop on High Energy Astrophyics Held in Nanjing, China, April 9-17, 1982,New York: Gordon and Breach Science Publishers S.A. 1982, 425[12]Baldwin, J. A

  12. A fast parallel code for calculating energies and oscillator strengths of many-electron atoms at neutron star magnetic field strengths in adiabatic approximation

    Science.gov (United States)

    Engel, D.; Klews, M.; Wunner, G.

    2009-02-01

    equations for the expansion coefficients, which is solved numerically, and, since the direct and exchange interaction potential terms depend on the wave functions, in a self consistent way. The iteration procedure is initialized by distributing the electrons on magnetic sublevels according to the level scheme of the hydrogen atom in intense magnetic fields. To speed up the calculations, the code is parallelized. The parallelization strategy is: a) each processor calculates one or several electrons, depending on the total number of processors, b) single-particle wave functions are broadcast from each processor to every other processor. As the coefficient vectors in the B-spline basis are small (dim≈20-25), there is only little communication between the nodes. Typical speedups by a factor of 20 are obtained on a 26-processor cluster of HP Compaq dc57750. Running time: The test runs provided only require a few seconds using 2 processors. References: [1] K. Werner, S. Dreizler, The classical stellar atmosphere problem, in: H. Riffert, K. Werner (Eds.), Computational Astrophysics, Computational and Applied Mathematics, Elsevier, 1998. [2] H. Ruder, G. Wunner, H. Herold, F. Geyer, Atoms in Strong Magnetic Fields, Springer, Heidelberg, 1994. [3] P.B. Jones, Mon. Not. R. Astron. Soc. 216 (1985) 503. [4] D. Neuhauser, K. Langanke, S.E. Koonin, Phys. Rev. A 33 (1986) 2084. [5] M.C. Miller, D. Neuhauser, Mon. Not. R. Astron. Soc. 253 (1991) 107. [6] M. Rajagopal, R.W. Romani, M.C. Miller, Astrophys. J. 479 (1997) 347. [7] K. Mori, C.J. Hailey, Astrophys. J. 564 (2002) 914. [8] M. Klews, Discretization methods for the investigation of atoms in time dependent electric fields, and in extremely strong magnetic fields (in German), Doctoral Thesis, University of Tübingen, 2003, http://www.theo1.physik.unistuttgart. de/forschung/sfb382a15/klews2003.ps.gz.

  13. Difficulties of First Years Elementary School Teachers with the Teaching of Astronomy. (Breton Title: Dificuldades de Professores dos Anos Iniciais do Ensino Fundamental em Relação ao Ensino da Astronomia. ) Dificultades de LOS Profesores de los Primeros Años de la Escuela Primaria en Relación a la Enseñanza de la Astronomía

    Science.gov (United States)

    Langhi, Rodolfo; Nardi, Roberto

    2005-12-01

    This paper reports Primary School teachers' discourses analysis about their difficulties related to the teaching of Astronomy. It reports partial data of a master's level research carried out in the last two years, named "An exploratory study for inserting Astronomy in primary school teachers' education" (LANGHI, 2004). The study took into consideration students' and teachers' common sense conceptions about astronomical phenomena, conceptual mistakes in textbooks, and Astronomy's suggestions given by the PCN (Parâmetros Curriculares Nacionais - The Brazilian National Curriculum Standards). The paper aims to characterize teachers' difficulties, in order to provide subsides to the implementation of an initial or continuing education program. This study is justified by the fact that courses plans like these only will be adapted to the teacher's (and students') reality, if there is a primary investigation about what the teachers really need to know about Astronomy. This fact was possible here by the enunciations interpretation of a teachers' sample using semi-structured interviews, according to discourse analysis procedures. The research outcomes show difficulties related to factors like: those of personal order, methodological, on teacher's formation, educational infrastructure and other related to information sources for educators. Este artigo, que relata as dificuldades de professores em relação ao ensino da Astronomia, faz parte de um estudo exploratório para a inserção da Astronomia na formação de professores dos anos iniciais do Ensino Fundamental. Esse estudo leva em consideração as concepções alternativas de alunos e professores sobre fenômenos astronômicos, os erros conceituais em livros didáticos e as sugestões de conteúdos de Astronomia constantes nos PCN (Parâmetros Curriculares Nacionais). Caracterizar as dificuldades dos professores é a questão central deste texto, apontando para o objetivo de contribuir com subsídios para um futuro

  14. The Shadow of a Gnomon Along a Year: Routine Observations and Teaching of Apparent Motion of the Sun and the Four Seasons. (Spanish Title: La Sombra de un Gnomon lo Largo de un Año: Observaciones de Rutina y la Enseñanza del Movimiento Aparente del Sol y Las Cuatro Estaciones.) A Sombra de um Gnômon ao Longo de um Ano: Observações Rotineiras e o Ensino do Movimento Aparente do Sol E das Quatro Estações

    Science.gov (United States)

    Trogello, Anderson Giovani; Danhoni Neves, Marcos Cesar; de Carvalho Rutz da Silva, Sani

    2013-12-01

    , al solsticio de junio, al equinoccio de septiembre y al solsticio de diciembre. Además, se dictaron clases teóricas en la sala de aula. Estos métodos buscaron construir conceptos en torno al movimiento aparente del Sol y la sucesión de las estaciones. Teniendo en cuenta los resultados de las actividades se aplicó una evaluación cuyos datos demuestran la existencia de un aprendizaje deseado por los estudiantes en cuanto a: el reconocimiento de los puntos cardinales, la descripción del movimiento solar aparente y la aparición de las estaciones y su alternancia a partir de observaciones astronómicas visuales sin instrumentos. Muitas concepções alternativas são reconhecidas entre os diversos grupos de estudantes, em especial nos da educação básica. Dentre elas, o movimento aparente do Sol, por mais quotidiano que seja, proporciona variadas interpretações. Deste modo, observar e registrar o movimento dos astros na abóboda celeste é uma tarefa necessária ao ensino de Astronomia. O trabalho que ora se apresenta propõe a apresentação dos resultados da observação do movimento aparente do Sol por intermédio da marcação da sombra de um gnômon vertical por alunos de uma turma do sexto ano do ensino fundamental de uma escola do campo do Paraná. O projeto em si ocorreu em quatro etapas, em datas próximas do equinócio de março, do solstício de junho, do equinócio de setembro e do solstício de dezembro. Além disso, foram desenvolvidas aulas teóricas em sala de aula. Tais métodos buscaram construir conceitos em torno da movimentação aparente do Sol e da alternância das estações do ano. Diante dos resultados provenientes das atividades desenvolvidas foi aplicada uma avaliação e os dados demonstraram um aprendizado desejado dos alunos quanto: ao reconhecimento dos pontos cardeais; à descrição do movimento solar aparente e a ocorrência das estações do ano e sua alternância a partir de observações astronômicas a olho nu.

  15. Development of Educational Resources to Include the Teaching of Astronomy in the First Years of the Basic Education. (Spanish Title: Desarrollo de Recursos Pedagógicos Para Incluir la Enseñanza de la Astronomía en los Primeros Años de la Educación Básica.) Desenvolvimento de Recursos Pedagógicos Para Inserir o Ensino de Astronomia nas Séries Iniciais do Ensino Fundamental

    Science.gov (United States)

    da Silva Morett, Samara; de Oliveira Souza, Marcelo

    2010-07-01

    ía y la vida cotidiana de los estudiantes. La inclusión de la astronomía en la escuela primaria es una manera de demostrar a los estudiantes cómo este campo está presente de forma activa en su vida cotidiana. Las clases que participan en el proyecto participaron en un estudio con el objetivo de proporcionar información a los conocimientos previos que tenían sobre los temas de la astronomía que se examinaron durante el proyecto. Con los experimentos realizados, y la ayuda de las nuevas tecnologías, conceptos astronómicos fueron presentados a los estudiantes de 4to y 5to año de la educación básica de una escuela municipal de Campos dos Goytacazes (RJ). Después de las presentaciones nuevos datos fueran colectados y se han llevado a cabo con el fin de verificar el nivel de aprendizaje alcanzado y se observó que el método utilizado fue una herramienta importante para ayudar al proceso de enseñanza y aprendizaje. El proyecto logró resultados satisfactorios. Neste trabalho será apresentado o desenvolvimento de recursos pedagógicos para a apresentação de conceitos de astronomia nas séries iniciais do ensino fundamental. Este material é composto por apresentações realizadas com o uso de novos recursos tecnológicos, pela fabricação de experimentos e a discussão de curiosidades relativas a esta área de conhecimento. Os experimentos foram construídos com material de baixo custo com o objetivo de permitir que os alunos envolvidos pudessem refazê-los em outras ocasiões. O material apresentado busca enfatizar a relação entre a astronomia e o cotidiano dos alunos. A inclusão da astronomia no ensino fundamental e uma forma de demonstrar aoestudante como esta área está presente de forma ativa em seu cotidiano. As turmas envolvidas no projeto participaram de uma pesquisa com o objetivo de obter dados relativos ao conhecimento prévio que possuíam sobre os tópicos de astronomia que foram considerados no decorrer do projeto. Com os experimentos

  16. First detection of Mars atmospheric hydroxyl: CRISM Near-IR measurement versus LMD GCM simulation of OH Meinel band emission in the Mars polar winter atmosphere

    Science.gov (United States)

    Todd Clancy, R.; Sandor, Brad J.; García-Muñoz, Antonio; Lefèvre, Franck; Smith, Michael D.; Wolff, Michael J.; Montmessin, Franck; Murchie, Scott L.; Nair, Hari

    2013-09-01

    Visible and near-IR Meinel band emissions originate from excited OH in the terrestrial upper atmosphere (Meinel, I.A.B. [1950]. Astrophys. J. 111, 555. http://dx.doi.org/10.1086/145296), and have recently been detected in the Venus nightside upper mesosphere (Piccioni, G. et al. [2008]. Astron. Astrophys. 483, L29-L33. http://dx.doi.org/10.1051/0004-6361:200809761). Meinel band observations support key studies of transport and photochemistry in both of these atmospheres. In the case of Mars, OH regulates the basic stability of the CO2 atmosphere to photolytic decomposition (to CO and O2, e.g. Parkinson, T.D., Hunten, D.M. [1972]. J. Atmos. Sci. 29, 1380-1390. http://dx.doi.org/10.1175/1520-0469(1972)0292.0.CO;2), and yet has never been measured. We present the first detection of Mars atmospheric OH, associated with CRISM near-IR spectral limb observations of polar night Meinel band emissions centered at 1.45 and 2.9 μm. Meinel band (1-0), (2-1), and (2-0) average limb intensities of 990 ± 280, 1060 ± 480, and 200 ± 100 kiloRayleighs (kR), respectively, are determined for 70-90 NS polar winter latitudes over altitudes of 40-56 km. Additional OH bands, such as (3-2), (3-1), and (4-2), present ⩽1σ measurements. Uncertainty in the (4-2) band emission rate contributes to increased uncertainty in the determination of the O2(1Δg) (0-0)/(0-1) band emission ratio A00/A01=47-12+26. An average profile retrieval for Mars OH polar nightglow indicates 45-55 km altitude levels for volume emission rates (VER) of 0.4 (2-0) to 2 (1-0, 2-1) × 104 photons/(cm3 s). Similar to polar night O2(1Δg) emission (e.g. Clancy, R.T. et al. [2012]. J. Geophys. Res. (Planets) 117, E00J10. http://dx.doi.org/10.1029/2011JE004018), Meinel OH band emission is supported by upper level, winter poleward transport of O and H in the deep Hadley solsticial circulations of Mars. The retrieved OH emission rates are compared to polar winter OH nightglow simulated by the LMD (Laboratoire de M

  17. Ritmitas mareales en la formación puncoviscana (S.L. en la localidad de Rancagua, Noroeste Argentino: Dinámica mareal y consideraciones paleoastronómicas Tidal rhythmites in the Puncoviscana Formation (s.l. at Rancagua locality, Northwestern Argentina: tidal dynamics and paleoastronomic considerations

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    Vanina L López de Azarevich

    2010-03-01

    Full Text Available Las ritmitas mareales constituyen una clara evidencia de sedimentación afectada por las mareas pudiendo preservar los períodos mareales inducidos astronómicamente al momento del depósito. Las investigaciones de secuencias periódicas mareales, acrecionadas vertical o lateralmente, en unidades modernas y antiguas, han experimentado notables avances en los últimos 25 años, excepto en la transición Neoproterozoico-eocámbrico. La Formación Puncoviscana (NO argentino está compuesta en la localidad de Rancagua por litofacies de cara de playa hasta plataforma distal, la cual incluye ritmitas mareales de edad neo-proterozoico- cámbrica temprana. Los períodos lunares involucrados en la sedimentación pueden ser aproximados mediante análisis armónicos con transformadas rápidas de Fourier a partir de datos crudos de espesores de láminas. Un sistema semidiurno con períodos tropicales de 26,64 días fue reconocido, a partir del cual se calculó la distancia Tierra-Luna en 3,78 x1010 cm. Estos resultados proporcionan información relevante acerca de la evolución de la órbita lunar a través del tiempo geológico. Los datos sugieren un evento astrofísico singular e irrepetible durante la transición Paleo-Mesoproterozoico con incremento en la velocidad de alejamiento hasta el Cámbrico Temprano, con eventos menores discretos en el Cámbrico Temprano y Paleozoico Superior con disminución del 50% de la velocidad de alejamiento.Tidal rhythmites are clear evidence of sedimentation affected by tides and could preserve tidal periods astronomically induced during the time of deposition. Investigations of tidal periodic sequences lateral or vertically accreted on modern and ancient units had improved notable advances during the last 25 years, but, there are no data on the Neoproterozoic-Early Cambrian transition. The Puncoviscana Formation (NW Argentina at Rancagua locality is composed by shoreface to offshore lithofacies, which includes tidal

  18. Mercury exosphere I. Global circulation model of its sodium component

    Science.gov (United States)

    Leblanc, Francois; Johnson, R. E.

    2010-10-01

    Our understanding of Mercury's sodium exosphere has improved considerably in the last 5 years thanks to new observations (Schleicher, H., Wiedemann, G., Wöhl, H., Berkefeld, T., Soltau, D. [2004]. Astron. Astrophys. 425, 1119-1124) and to the publication of a summary of the large set of ground based observations (Potter, A.E., Killen, R.M., Morgan, T.H. [2007]. Icarus 186, 571-580; Potter, A.E., Killen, R.M. [2008]. Icarus 194, 1-12; Potter et al., 2009). In particular, the non-uniformity in longitude of the dayside sodium distribution (the dawn/dusk asymmetry) has now been clearly observed. This suggests that Mercury's sodium exosphere is partly driven by a global day to nightside migration of the volatiles. One of the key questions remaining is the nature of the prevailing sodium ejection mechanisms. Because of the uncertain parameters for each ejection mechanisms, solving this problem has been difficult as indicated by the numerous papers over the last 15 years with very different conclusions. In addition, the variation of the size and of the spatial distribution of the surface reservoir (Leblanc, F., Johnson, R.E. [2003]. Icarus 164, 261-281) varies with distance from the Sun affecting the importance of each ejection mechanism on Mercury's orbital position. We here present an updated version of the Leblanc and Johnson (Leblanc, F., Johnson, R.E. [2003]. Icarus 164, 261-281) model. We take into account the two populations of sodium in the surface reservoir (Hunten, D.M., Morgan, T.M., Shemansky, D.M. [1988]. The Mercury atmosphere. In: Vilas, F., Chapman, C., Matthews, M. (Eds.), Mercury. University of Arizona Press, Tucson, pp. 562-612), one ambient population (physisorbed in the regolith with low binding energy) and one source population (chemisorbed coming from grain interior or from fresh dust brought to the surface and characterized by a higher binding energy). We also incorporate a better description of the solar wind sputtering variation with solar

  19. Direito à Educação no Brasil e dívida educacional: e se o povo cobrasse? Right to education in Brazil and the educational debt: what if the people actually demanded it?

    Directory of Open Access Journals (Sweden)

    Alceu Ravanello Ferraro

    2008-08-01

    Full Text Available Inicia-se tratando do direito à Educação no quadro dos direitos fundamentais da pessoa humana e do conceito de dívida educacional que decorre da não-realização do direito público subjetivo de cada cidadão e cidadã à Educação Fundamental completa, conforme estabelecido na Constituição de 1988. Utilizando como parâmetro a informação censitária sobre o número de anos de estudo concluídos com aprovação levantados no Censo 2000, estima-se que, nesse ano, o Estado brasileiro devia, aos 119,6 milhões de pessoas de 15 anos ou mais, a astronômica cifra de 325,5 milhões de anos de estudo não realizados na idade própria - uma média de quase três anos por pessoa. São projetados também os investimentos necessários em termos de professores e salas de aula/turno-ano para o resgate da dívida. Mostra-se ainda que a dívida estimada com base na Pesquisa Nacional por Amostra de Domicílios 2005 (316,4 milhões de anos de estudo devidos representa uma diminuição muito pequena em relação ao Censo 2000. Por fim, aborda-se a questão dos atores ou agentes da efetividade do direito à Educação e dos instrumentos de exigibilidade que a legislação põe à disposição desses mesmos agentes. Conclui-se afirmando que está posto aí, para a sociedade em geral e para educadores e educadoras em particular, o grande desafio de despertar nas pessoas humildes a consciência de que elas efetivamente têm direito à Educação e de que dispõem de meios para cobrar do Estado esse direito.We start by considering the right to Education within the framework of the fundamental human rights, and the ensuing concept of educational debt, which follows from the failure to enforce the subjective public right of each citizen to a complete Fundamental Education as established by the 1988 Brazilian Constitution. Based on the 2000 census information on the number of years of schooling successfully concluded, we estimate that in that year the Brazilian

  20. Two-Body Convection in the Mantle of the Earth: E/W Asymmetry, Under Astronomically Determined Tilt in g

    Science.gov (United States)

    Bostrom, R. C.

    2002-12-01

    Wegener to the present day [3], identifying a 'global tectonic polarity'; and westward drift, of which the asymmetry may be regarded as its engine. In sum, Earth's mantle is subject to three non-reversing force systems acting in the direction of causing net surface-west horizontal displacement, namely: I, Weak and tectonically insignificant forces ('tidal drag'), in unison constituting GH Darwin's tidal retarding couple; II, The forces inducing cumulative vorticity (TVI) [4] in an imperfectly elastic mantle, under passage of tidal M2. The operation of this system is ineluctable, and based on stress and energy consumption is likely to be significant, but its quantification requires separation of the marine from the bodily tidal energy dissipation utilizing secondary effects [4,5]; and III, Buoyancy-forces under convection now recognized as fundamental in geotectonics; - as normally modeled, greatly superadiabatic and dissipative, but within a field gconv minutely west-tilted, rather than artifically devoid of the Moon. Asymmetry of its internal gravity is unique to the asynchronous member of Kuiper's Earth-Moon double planet. The asymmetry distinguishes Earth's steady-state convection from the episodic regime of its moonless and almost non-rotating 'identical twin', Venus. Refs: [1] Tuoma, J. and J. Wisdom, 1994. Astron. J. 108(5) 1943-1961. [2] RCB, 2002. Episodes: J. Int. Geosc. 25(3), in pr. [3] Doglioni, C., 1993. J. Geol. Soc. 150, 991-1002. [4] RCB, 2000. Tectonic Consequences of Earth's Rotation (Oxford UP) s.4.3. [5] Lambeck, K., 1988. Geophysical Geodesy: The Slow Deformations of the Earth (Oxford UP) s. 11.3.

  1. Generation of ion temperature anisotropy in kinetic hybrid-Vlasov simulations (Invited)

    Science.gov (United States)

    Perrone, D.; Valentini, F.; Servidio, S.; Dalena, S.; Veltri, P.

    2013-12-01

    . Carbone, LRSP 2, 4 (2005) [2] E. Marsch, LRSP 3, 1 (2006) [3] E. Marsch, K.-H. Mühlh.user, R. Schwenn, et al., J. Geophys. Res. 87, A1 (1982) [4] E. Marsch, K.-H. Mühlh.user, R. Schwenn, et al., J. Geophys. Res. 35, A1 (1982) [5] J.C. Kasper, A.J. Lazarus and S.P. Gary, Phys. Rev. Lett. 101, 261103 (2008) [6] F. Valentini, P. Trávnícek, F. Califano et al., J. Comput. Phys. 225, 753 (2007) [7] D. Perrone, F. Valentini and P. Veltri, Astrophys. J. 741, 43 (2011) [8] D. Perrone, F. Valentini, S. Servidio et al., Astrophys. J. 762, 99 (2013) [9] B.A. Maruca, J.C. Kasper and S.P. Gary, Astrophys. J. 748, 137 (2012) [10] S. Bourouaine, E. Marsch and F.M. Neubauer, Astron. and Astrophys. 536, A39 (2011) [11] P. Wu, S. Perri, K. Osman, et al., Astrophys. J. Lett. 763, L30 (2013)

  2. Comparison of Regression and Neural Networks Models to Estimate Solar Radiation Comparación de Regresión y Modelos de Redes Neuronales para Estimar la Radiación Solar

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    Mónica Bocco

    2010-09-01

    ón multicapa, para estimar la radiación solar global diaria y comparar la eficiencia de los mismos en su aplicación para una región de la Provincia de Salta, Argentina. Se utilizaron datos de heliofanía relativa, temperaturas máxima y mínima, precipitación, precipitación binaria y radiación solar astronómica provistos por la Estación Experimental Salta, Instituto Nacional de Tecnología Agropecuaria (INTA, Argentina, correspondientes al período 1996-2002. Tanto para los modelos de redes neuronales como para las regresiones lineales se consideraron tres alternativas de combinaciones de los parámetros meteorológicos, obteniéndose buenos resultados con ambas metodologías de predicción, con valores de la raíz del error cuadrático medio variando desde 1.99 a 1.66 MJ m-2 d-1 y coeficientes de correlación de 0.88 a 0.92. Se concluye que ambos, los modelos de redes neuronales y las regresiones lineales, pueden ser usados para predecir en forma adecuada la radiación solar global diaria; si bien las redes neuronales produjeron mejores resultados.

  3. Emergence of Habitable Environments in Icy World Interiors

    Science.gov (United States)

    Neveu, Marc

    2016-07-01

    separation method that takes advantage of the density contrast between cells and sediment and preserves cellular elemental contents [11]. Using this method, I showed that in spite of the tremendous physical, chemical, and taxonomic diversity of Yellowstone hot springs, the composition of microorganisms there is surprisingly ordinary [12]. This suggests the existence of a stoichiometric envelope common to all life as we know it. Thus, future planetary investigations could use elemental fingerprints to assess the astrobiological potential of hydrothermal settings beyond Earth. References: [1] US National Research Council (2011)Vision & Voyages in the Decade 2013-2022. [2] Hussmann et al. (2006) Icarus 185, 258-273. [3] Desch et al. (2009) Icarus 202, 694-714. [4] Neveu et al. (2015) JGR 120, 123-154. [5] Neveu & Rhoden, in prep. [6] De Sanctis et al. (2015) Nature 528, 241-244. [7] Hsu et al. (2015) Nature 519, 207-210. [8] Wasson & Kallemeyn (1988) Phil Trans R Soc London A 325, 535-544. [9] Mumma & Charnley (2011) Annu Rev Astron Astrophys 49, 471. [10] Neveu et al., in revision. [11] Neveu et al. (2014) Limn Oceanogr 12, 519-529. [12] Neveu et al. (2016) Geobiology 14, 33-53.

  4. Distant activity of Comet C/2002 VQ94 (LINEAR): Optical spectrophotometric monitoring between 8.4 and 16.8 au from the Sun

    Science.gov (United States)

    Korsun, Pavlo P.; Rousselot, Philippe; Kulyk, Irina V.; Afanasiev, Viktor L.; Ivanova, Oleksandra V.

    2014-04-01

    distance of 16.84 au, when the activity had probable ceased. The B-V and V-R colors were estimated to be 1.07 ± 0.05 and 0.54 ± 0.03 respectively. The effective nucleus radius of 48 ± 2 km is in agreement with the previously published results, obtained from the observations of the comet during its early inactive stage (Jewitt, D. [2005]. Astron. J. 129, 530-538; Weiler, M., Rauer, H., Sterken, C. [2011]. Icarus 212, 351-366).

  5. The global surface composition of 67P/CG nucleus by Rosetta/VIRTIS. (I) Prelanding mission phase

    Science.gov (United States)

    Filacchione, Gianrico; Capaccioni, Fabrizio; Ciarniello, Mauro; Raponi, Andrea; Tosi, Federico; De Sanctis, Maria Cristina; Erard, Stéphane; Morvan, Dominique Bockelée; Leyrat, Cedric; Arnold, Gabriele; Schmitt, Bernard; Quirico, Eric; Piccioni, Giuseppe; Migliorini, Alessandra; Capria, Maria Teresa; Palomba, Ernesto; Cerroni, Priscilla; Longobardo, Andrea; Barucci, Antonella; Fornasier, Sonia; Carlson, Robert W.; Jaumann, Ralf; Stephan, Katrin; Moroz, Lyuba V.; Kappel, David; Rousseau, Batiste; Fonti, Sergio; Mancarella, Francesca; Despan, Daniela; Faure, Mathilde

    2016-08-01

    . The parallel coordinates method (Inselberg [1985] Vis. Comput., 1, 69-91) has been used to identify associations between average values of the spectral indicators and the properties of the geomorphological units as defined by (Thomas et al., [2015] Science, 347, 6220) and (El-Maarr et al., [2015] Astron. Astrophys., 583, A26). Three classes have been identified (smooth/active areas, dust covered areas and depressions), which can be clustered on the basis of the 3.2 μm organic material's band depth, while consolidated terrains show a high variability of the spectral properties resulting being distributed across all three classes. These results show how the spectral variability of the nucleus surface is more variegated than the morphological classes and that 67P/CG surface properties are dynamical, changing with the heliocentric distance and with activity processes.

  6. Resolving stellar populations with crowded field 3D spectroscopy

    Science.gov (United States)

    Kamann, S.; Wisotzki, L.; Roth, M. M.

    2013-01-01

    effects of PSF mismatch and other systematics. We close with an outlook by applying our method to a simulated globular cluster observation with the upcoming MUSE instrument at the ESO-VLT. 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).Based on observations made with the NASA/ESA Hubble Space Telescope, and obtained from the Hubble Legacy Archive, which is a collaboration between the Space Telescope Science Institute (STScI/NASA), the Space Telescope European Coordinating Facility (ST-ECF/ESA), and the Canadian Astronomy Data Centre (CADC/NRC/CSA).

  7. Ionization structure and chemical abundances of the Wolf-Rayet nebula NGC 6888 with integral field spectroscopy

    Science.gov (United States)

    Fernández-Martín, A.; Martín-Gordón, D.; Vílchez, J. M.; Pérez Montero, E.; Riera, A.; Sánchez, S. F.

    2012-05-01

    slight underabundance in O/H; ii) an outer shell very intense in [OIII]λ5007 Å corresponding to the main sequence bubble broken up as a consequence of the collision between supergiant and WR shells. Nitrogen and oxygen do not appear enhanced here, but helium appears enriched; iii) and finally it includes an external and faint shell that surrounds the whole nebula like a thin skin representing the early interaction between the winds from the main sequence star with the ISM for which typical circumstellar abundances are derived. Based on observations collected at the Centro Astronómico Hispano Alemán (CAHA) at Calar Alto, operated jointly by the Max-Planck-Institut für Astronomie and the Instituto de Astrofísica de Andalucía (CSIC).Table 3 is available in electronic form at http://www.aanda.org

  8. Modelos MLG e MAG para análise da associação entre poluição atmosférica e marcadores de morbi-mortalidade: uma introdução baseada em dados da cidade de São Paulo GLM and GAM model for analyzing the association between atmospheric pollution and morbidity-mortality markers: an introduction based on data from the city of São Paulo

    Directory of Open Access Journals (Sweden)

    Gleice Margarete de Souza Conceição

    2001-11-01

    Full Text Available Este estudo, descreve e compara duas classes de modelos - os Modelos Lineares Generalizados (MLG e os Modelos Aditivos Generalizados (MAG - que podem ser utilizadas para avaliar a associação entre poluição atmosférica e marcadores de morbi-mortalidade. Enfoca os MAG como uma alternativa para a modelagem de relações não lineares não especificadas, e mostra que essa classe de modelos constitui uma boa opção para representar tanto a sazonalidade quanto a relação entre o desfecho e as variáveis meteorológicas. Como exemplo de aplicação é avaliada a associação entre mortalidade em idosos e poluição atmosférica na cidade de São Paulo no período de 1994 a 1997. Os dados de mortalidade foram obtidos do Programa de Aprimoramento das Informações de Mortalidade (PRO-AIM e as concentrações diárias de poluentes (PM10, SO2, CO, e ozônio foram obtidas da Companhia de Tecnologia de Saneamento Ambiental (CETESB. Informações acerca da temperatura e umidade relativa do ar foram obtidas do Instituto Astronômico e Geofísico da Universidade de São Paulo (IAG-USP. As duas classes de modelos produziram resultados coerentes, mas os modelos estatisticamente mais sofisticados tiveram mais poder para detectar efeitos significantes. Foram observadas associações entre mortalidade e os níveis de CO, SO2 e, em menor escala, PM10. As associações observadas foram dose-dependente e evidentes após um curto período de exposição.In this study, we have described and compared two classes of models - the Generalized Linear Models (GLM and the Generalized Additive Models (GAM _ which can be used to evaluate the association between atmospheric pollution and morbidity and mortality counts. We consider GAM as an alternative for modeling unspecific nonlinear relationships, and show that this class of models constitute a good option to represent both seasonality and the relation between the outcome and the meteorological variables. As an

  9. Nuevo algoritmo de detección y corrección de píxeles anómalos en imágenes A new algorithm for detecting and correcting bad pixels in infrared images

    Directory of Open Access Journals (Sweden)

    Restrepo Gir��n Andrés David

    2010-08-01

    Full Text Available Se expone un nuevo algoritmo de procesamiento de imágenes para detectar y corregir píxeles anómalos que resalten de manera individual entre sus vecinos en imágenes de una secuencia térmica obtenida a partir de un procedimiento de termografía activa, sin afectar la apariencia global de cada imagen, como ocurre al emplear una estrategia clásica de filtrado espacial. Como resultado principal de este filtrado selectivo, se detectan y reemplazan en un alto porcentaje aquellos píxeles defectuosos de fabricación o por el uso continuo del dispositivo CCD de la cámara infrarroja, lo cual re- duce el riesgo de malas interpretaciones en el análisis posterior. Para el desarrollo y prueba del algoritmo propuesto se utilizaron secuencias de video tomadas con una cámara Cincinnati Electronics de indio-antimonio (InSb para inspeccionar láminas de CFRP (plástico reforzado con fibra de carbono mediante la técnica de termografía activa. Los resultados del algoritmo se comparan con una lista de píxeles defectuosos dada por el fabricante de la cámara, arrojando un porcentaje de coincidencia de alrededor del 70%. El presente trabajo toma relevancia al considerar que en la literatura científica se encuentran muy pocos estudios en este campo, centrándose la mayoría en el preprocesamiento de imágenes astronómicas; además, en Colombia se está en una etapa de introducción creciente de técnicas de evaluación no destructiva por termografía (ENDT en amplios sectores industriales que incluyen generación y transmisión de energía, in- genios azucareros y aeronáutica militar, entre otros.An image processing algorithm detects and replaces abnormal pixels individually, highlighting them amongst their neighbours in a sequence of thermal images without affecting overall texture, like classical filtering does. Bad pixels from manufacture or constant use of a CCD device in an IR camera are thus detected and replaced with a very good success rate

  10. Vesta and low gravity impact mixing

    Science.gov (United States)

    Hoffmann, Martin; Nathues, Andreas; Vincent, Jean-Baptiste; Sierks, Holger

    2013-04-01

    impacts into granular material lead to anything but a simple crater morphology. Unusual scaling laws (Uehara et al. 2003) and much more diverse phase patterns than in ordinary solid media have to be taken into account, if a consistent interpretation of the formation of a crater in very deep regolith is attempted (e.g. Opsomer et al. 2011). Additional effects are due to the low gravity environment on a small planetary body like Vesta (Tancredi et al. 2012). On Vesta many apparent counterparts to the results of the experiments can be found, as demonstrated by some examples. On a global scale, the multitude of small, unresolved primary and secondary impacts into the granular regolith contributes to the observed maturity on Vesta even after short time scales. References Cook, M. A., Mortensen, K. S. 1967. Impact cratering in granular materials. J. Appl. Phys. 38, 5125-5128. Daniels, K. E., Coppock, J. E., Behringer, R. P. 2004. Dynamics of meteor impacts. Chaos 14, 84. Daraio, C., Nesterenko, V. F., Herbold, E. B., Jin S. 2006. Energy trapping and shock desintegration in a composite granular medium. Phys. Rev. Lett. 96, 058002, 1-4. Opsomer, E., Ludewig, F., Vandewalle, N. 2011. Phase transitions in vibrated granular systems in microgravity. Phys. Rev. E84, 051306, 1-5. Rivas, N., Ponce, S., Gellet, B., Risso, D., Soto, R., Cordero, P. 2011. Sudden chain energy transfer events in vibrated granular media. Phys. Rev. Lett. 106, 088001, 1-4. Tancredi, G., Maciel, A., Heredia, L., Richeri, P., Nesmachnow, S. 2012. Granular physics in low-gravity environments using discrete element method. Monthly Not. Royal Astron. Soc. 420, 3368-3380. Uehara, J. S., Ambroso, M. A., Ojha, R. J., Durian, D. J. 2003. Low-speed impact craters in loose granular media. Phys. Rev. Lett. 90, 194301, 1-4.

  11. The application of simple mass spectrometers to planetary sub-surface sampling using penetrators

    Science.gov (United States)

    Sheridan, Simon; Morse, Andrew; Bardwell, Max; Barber, Simeon; Wright, Ian

    2010-05-01

    (1-4), 363-387. Todd, J.F.J., Barber, S.J., Wright, I.P., Morgan, G.H., Morse, A.D., Sheridan, S., Leese, M.R., Maynard, J., Evans, S.T., Pillinger, C.T. et al. (2007). Ion trap mass spectrometry on a comet nucleus: the Ptolemy instrument and the Rosetta space mission. J. Mass Spectrom. 42,1-10. Pillinger C. T., and Wright I. P. (1993). MODULUS - Methods Of Determining and Understanding Light elements from Unequivocal Stable isotope composition. A type 2 proposal submitted to the RoLand Cometary Lander of the ESA International Rosetta Mission for the provision of Ptolemy - an evolved gas analyser. Richter L., Coste P., Grzesik A., Magnani P., Nadalini R., Neuhaus D., Re E., Romstedt J., Sims M. and Sohl F. (2005). Instrumented Moles for Planetary Subsurface Regolith Studies. Geophysical Research Abstracts, Vol. 7, 08659 A. Smith A.,. Crawford I. A., Gowen R. A., Ball A. J., Barber S. J., Church P., Coates A. J., Gao Y., Griffiths A. D., Hagermann A.,•Joy K. H., Phipps A., Pike W. T., Scott R., Sheridan S., Sweeting M., Talboys D.,•Tong V.,•Wells N.,• Biele J., Chela-Flores J.,•Dabrowski B., Flannagan J., Grande M., Grygorczuk J., Kargl G.,. Khavroshkin O. B.,•Klingelhoefer G., Knapmeyer M.,• Marczewski W., McKenna-Lawlor S.,•Richter L., Rothery D. A., Seweryn K., Ulamec S., Wawrzaszek R., Wieczorek M., Wright I. P. and Sims M. (2009). LunarEX - a proposal to cosmic vision. Exp Astron 23:711-740: DOI 10.1007/s10686-008-9109-6

  12. Análise Temporal da Coma de CO+ no Cometa P/Halley

    Science.gov (United States)

    Voelzke, M. R.; Schlosser, W.; Schmidt-Kaler, Th.

    1995-08-01

    Observações fotográficas e fotoelétricas da coma de gás ionizado do cometa P/Halley a nível de CO+ em 4250 angstroms fizeram parte do programa de Monitoramento do Halley desenvolvido pela Universidade de Bochum (Ruhr-Universitaet Bochum) na Alemanha, realizado de 17 de fevereiro a 17 de abril de 1986 no European Southern Observatory (ESO) em La Silla (Chile). Nesta faixa espectral é possível observar a contínua formação, bem como o movimento e expansão das estruturas de plasma. Para observar a morfologia destas estruturas foram analisadas 32 placas fotográficas de CO+ (placas de vidro) do cometa P/Halley. Tais placas possuem um campo de visão de 28,6 por 28,6 graus sendo obtidas entre 29 de março e 17 de abril de 1986 com tempos de exposição entre 20 e 120 minutos. Todas as placas foram digitadas com o auxílio de um microdensitômetro PDS 2020 GM (Photometric Data System) do Instituto Astronómico da Westfaelischen Wilhelms-Universitaet em Muenster, Alemanha (um pixel = 25 por 25 micrômetros correspondendo aproximadamente a 46,88 por 46,88 segundos de arco). Após a digitação os dados foram reduzidos à intensidades relativas, sendo que os posssíveis de calibração também foram reduzidos à intensidades absolutas, expressas em termos de densidade colunar utilizando-se dos sistemas de tratamento de imagens MIDAS (Munich Image Data Analysis System; ESO - Image Processing Group, 1988) e IHAP (Image Handling And Processing; Middleburg, 1983). Com o auxílio do método de teta mínimo de Stellingwerf (Stellingwerf, 1978) obteve-se um período de 2,22 +/- 0,09 dias a partir da análise de estruturas na coma de plasma através da subtração de imagens subsequentes. Este método foi comparado com o método de Fourier. Provavelmente exista um segundo ciclo com período aproximado de 3,6 dias. A idéia de subtrair imagens subsequentes é devido ao fato de que os efeitos de rotação são apenas 10% dos fenômenos de distribuição gasosa. Portanto as

  13. The proximity of Mercury's spin to Cassini state 1 from adiabatic invariance

    Science.gov (United States)

    Peale, S. J.

    2006-04-01

    In determining Mercury's core structure from its rotational properties, the value of the normalized moment of inertia, C/MR, from the location of Cassini 1 is crucial. If Mercury's spin axis occupies Cassini state 1, its position defines the location of the state, where the axis is fixed in the frame precessing with the orbit. Although tidal and core-mantle dissipation drive the spin to the Cassini state with a time scale O(10) years, the spin might still be displaced from the Cassini state if the variations in the orbital elements induced by planetary perturbations, which change the position of the Cassini state, cause the spin to lag behind as it attempts to follow the state. After being brought to the state by dissipative processes, the spin axis is expected to follow the Cassini state for orbit variations with time scales long compared to the 1000 year precession period of the spin about the Cassini state because the solid angle swept out by the spin axis as it precesses is an adiabatic invariant. Short period variations in the orbital elements of small amplitude should cause displacements that are commensurate with the amplitudes of the short period terms. The exception would be if there are forcing terms in the perturbations that are nearly resonant with the 1000 year precession period. The precision of the radar and eventual spacecraft measurements of the position of Mercury's spin axis warrants a check on the likely proximity of the spin axis to the Cassini state. How confident should we be that the spin axis position defines the Cassini state sufficiently well for a precise determination of C/MR? By following simultaneously the spin position and the Cassini state position during long time scale orbital variations over past 3 million years [Quinn, T.R., Tremaine, S., Duncan, M., 1991. Astron. J. 101, 2287-2305] and short time scale variations for 20,000 years [JPL Ephemeris DE 408; Standish, E.M., private communication, 2005], we show that the spin axis

  14. Dynamical Evolution of Open Star Clusters

    Science.gov (United States)

    de La Fuente Marcos, Raúl

    1998-09-01

    hierarchical systems is also considered in detail. Some questions concerning multicomponent clusters, such as the preferential evaporation of light stars, are reviewed. The global results are compared with the observational data of actual clusters from The Database for Stars in Open Clusters: BDA1 (J.-C. Mermilliod, in ASP Conf. Ser. 90, The Origins, Evolution, and Destinies of Binary Stars in Clusters, ed. E. F. Milone & J.-C. Mermilliod [San Francisco: ASP, 1996]). The likely observational properties of the final stages of the evolution of open clusters are also investigated, and the results are compared with the available observational data (L. O. Loden, Ap&SS, 199, 165 [1993]; R. P. Stefanik, J. R. Caruso, G. Torres, S. Jha, & D. W. Latham, Baltic Astron., 6, 137 [1997]). It is found that they depend on the membership of the cluster, the abundance of primordial binaries, and the initial mass function. The final cluster remnant is very rich in binaries and hierarchical systems. Remnants of poorly populated clusters are relatively easy to identify because they contain early-type stars. Remnants of rich open clusters are difficult to detect and might exist in large numbers. The detection of rich open clusters' remnants (OCRs) is a great challenge for the largest available telescopes because they contain only faint stars. It is possible that some of the oldest known open clusters are in fact remnants of densely populated (N 40,000) clusters. The existence of a large number of OCRs may be relevant for dark matter in the Galactic disk. This hypothesis could be tested by using the capabilities of the proposed global astrometry mission Global Astrometric Interferometer for Astrophysics (GAIA).

  15. Evolved stars and the origin of abundance trends in planet hosts

    Science.gov (United States)

    Maldonado, J.; Villaver, E.

    2016-04-01

    Galaxy. The sample of giants contains stars that are more massive and younger than their main-sequence counterparts. This leads to a sample of stars that are possibly less contaminated by stars that were not born in the solar neighbourhood, leading to no chemical differences between planet and non-planet hosts. The sample of main-sequence stars may contain more stars from the outer disc (specially the non-planet host sample) which might lead to the differences observed in the chemical trends. Based on observations made with the Mercator Telescope; on observations made with the Nordic Optical Telescope; on observations made with the Italian Telescopio Nazionale Galileo; on observations collected at the Centro Astronómico Hispano Alemán (CAHA) at Calar Alto; and on data products from observations made with ESO Telescopes at the La Silla Paranal Observatory under programme ID 072.C-0488(E), 080.D-0347(A), 081.D-0870(A), 087.C-0831(A), and 183.C-0972(A).Tables B.1-B.3 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/588/A98

  16. Hemocompatibility of DLC coatings synthesized by ion beam assisted deposition

    Institute of Scientific and Technical Information of China (English)

    LI; Dejun

    2001-01-01

    [1]Gallagher, J. J., Simpson, J. A., Search for trapped electrons and a magnetic moment at Mars by Mariner IV, Science, 1965, 149: 1233—1239.[2]Russell, C. T., The magnetic field of Mars: Mars 3 evidence reexamined, Geophys. Res. Lett., 1978, 5: 81—86.[3]Riedler, W., Schwingenschun, K., Lichtenegger, H. et al., Interaction of solar wind with the planet Mars: Phobos 2 magnetic field observations, Planet. Space Sci., 1991, 39: 75—81.[4]Gringauz, K. I., What was known about the Martian magnetosphere before Phobos-2 mission, Planet. Space Sci., 1991, 39: 73—74.[5]Acuna, M. H., Connerney, J. E. P., Wasilewski, P. et al., Magnetic field and plasma observations at Mars: Initial results of the Mars global surveyor mission, Science, 1998, 279: 1676—1680.[6]Mohlmann, D., Riedler. W., Rustenbuch, J. et al., The question of an internal Martian magnetic field, Planet. Space Sci., 1991, 39: 83—88.[7]Shi, J. K., Liu, Z. X., Zhang, T. L., A theoretical study on the O+ ions of the Martian magnetosphere, Chin Astron Astrophys., 1999, 23: 377—383.[8]Rosenbauer, H., Shutte, N., Apathy, I. et al., Ions of Martian origin and plasma sheet in the Martian magnetotail: Initial results of TAUS experiment, Nature, 1989, 341: 612—614.[9]Lundin, R., Zakharov, A., Pelinen, R. et al., ASPERA/Phobos measurements of the ion outflow from the Martian ionosphere, Geophy. Res. Lett., 1990, 17: 873—876.[10]Verigin, M. I., Shutte, N. M., Galeev, A. A. et al., Ions of planetary origin in the Martian magnetosphere (Phobos 2 / TAUS experiment), Planet. Space Sci., 1991, 39: 131—137.[11]Lundin, R., Zakharov, A., Pelinen, R. et al., First measurements of the ionospheric plasma escape from Mars, Nature, 1989, 341: 609—612.[12]Lammer, H., Bauer, S. J., Nonthermal atmospheric escape from Mars and Titan, J. Geophys. Res., 1991, 96: 1819—1826.[13]Haider, S. A., O+ escape in the polar ion exosphere of Mars, Adv. Space Res., 1995, 16: 49

  17. Influence of tail-like magnetic field on O+ ion distribution in the Martian magnetosphere

    Institute of Scientific and Technical Information of China (English)

    SHI; Jiankui

    2001-01-01

    [1]Gallagher, J. J., Simpson, J. A., Search for trapped electrons and a magnetic moment at Mars by Mariner IV, Science, 1965, 149: 1233—1239.[2]Russell, C. T., The magnetic field of Mars: Mars 3 evidence reexamined, Geophys. Res. Lett., 1978, 5: 81—86.[3]Riedler, W., Schwingenschun, K., Lichtenegger, H. et al., Interaction of solar wind with the planet Mars: Phobos 2 magnetic field observations, Planet. Space Sci., 1991, 39: 75—81.[4]Gringauz, K. I., What was known about the Martian magnetosphere before Phobos-2 mission, Planet. Space Sci., 1991, 39: 73—74.[5]Acuna, M. H., Connerney, J. E. P., Wasilewski, P. et al., Magnetic field and plasma observations at Mars: Initial results of the Mars global surveyor mission, Science, 1998, 279: 1676—1680.[6]Mohlmann, D., Riedler. W., Rustenbuch, J. et al., The question of an internal Martian magnetic field, Planet. Space Sci., 1991, 39: 83—88.[7]Shi, J. K., Liu, Z. X., Zhang, T. L., A theoretical study on the O+ ions of the Martian magnetosphere, Chin Astron Astrophys., 1999, 23: 377—383.[8]Rosenbauer, H., Shutte, N., Apathy, I. et al., Ions of Martian origin and plasma sheet in the Martian magnetotail: Initial results of TAUS experiment, Nature, 1989, 341: 612—614.[9]Lundin, R., Zakharov, A., Pelinen, R. et al., ASPERA/Phobos measurements of the ion outflow from the Martian ionosphere, Geophy. Res. Lett., 1990, 17: 873—876.[10]Verigin, M. I., Shutte, N. M., Galeev, A. A. et al., Ions of planetary origin in the Martian magnetosphere (Phobos 2 / TAUS experiment), Planet. Space Sci., 1991, 39: 131—137.[11]Lundin, R., Zakharov, A., Pelinen, R. et al., First measurements of the ionospheric plasma escape from Mars, Nature, 1989, 341: 609—612.[12]Lammer, H., Bauer, S. J., Nonthermal atmospheric escape from Mars and Titan, J. Geophys. Res., 1991, 96: 1819—1826.[13]Haider, S. A., O+ escape in the polar ion exosphere of Mars, Adv. Space Res., 1995, 16: 49

  18. El urbanismo Inka y su vinculación con mesoclimas en el sitio "El Shincal de Quimivil" (Provincia de Catamarca, Argentina Inka urbanism associated with mesoclimatic conditions at the site "El Shincal de Quimivil" (Catamarca province, Argentina

    Directory of Open Access Journals (Sweden)

    Aylen Capparelli

    2006-12-01

    Full Text Available Los Inkas gestionaron el ambiente, de las distintas regiones que ocuparon, sobre la base tanto de sus conocimientos astronómicos -solares y lunares- como de aquellos referidos a la ecología y calendario agrícola -del maíz en especialde cada región. La producción excedente de una población se redistribuía luego en base a un sistema de almacenaje propio de este Estado. Dentro de este marco, se propone que el conocimiento de la diversidad de hábitats, y de los factores ecológicos a ellos asociados, les sirvió a los Inkas para planificar y garantizar el buen funcionamiento de cada unidad arquitectónica en cada centro administrativo. Por lo tanto, el objetivo principal de este trabajo es determinar si existe alguna vinculación entre las distintas condiciones mesoclimáticas que se encuentran en el lugar de implantación del sitio Inka El Shincal de Quimivil (Catamarca, Argentina y la distribución espacial de tres sectores arquitectónicofuncionales diferentes (almacenaje, habitacional, cultivo y un testigo (plaza. Se analizaron en forma univariada y multivariada 6 variables climáticas. Por sus altos valores de déficit de saturación de vapor del aire (DS, capacidad evaporante del aire y temperatura del suelo, el sector de almacenaje resultó el sector más propicio para lograr el secado y la preservación de los granos. El sector habitacional, mostró bajos DS y capacidad evaporante en primavera y verano, lo que contribuyó a condiciones más confortables bajo las elevadas temperaturas de esas estaciones. El sector cultivos, tuvo baja capacidad evaporante durante días con Zonda, y su mesoclima generalmente moderado, es el que más se ajusta a los requerimientos agroecológicos del maíz.The Inkas managed the environment of the different regions they occupied based on their astronomical and agroecological knowledge, especially in relation to maize. Surplus production was redistributed through a well developed storage system. Within

  19. Aqueous processing of organic compounds in carbonaceous asteroids

    Science.gov (United States)

    Trigo-Rodríguez, Josep Maria; Rimola, Albert; Martins, Zita

    2015-04-01

    A (2002) Clay mineral-organic matter relationships in the early solar system. Meteorit Planet Sci 37:1829-1833. Rimola A, Costa D, Sodupe M, Lambert JF, Ugliengo P (2013) Silica surface features and their role in the adsorption of biomolecules: computational modeling and experiments. Chem Rev 113:4216-4313. Rimola A, Sodupe M, Ugliengo P (2007) Aluminosilicate as promoters for peptide bond formation: an assessment of Bernal's hypothesis by ab initio methods. J Am Chem soc 129:8333-8344 Trigo-Rodríguez JM, Moyano-Cambero CE, Llorca J, Formasier S, Barucci MA, Belskaya I, Martins Z, Rivkin AS, Dotto E, Madiedo JM, Alonso-Azcárate J (2014) UV to far-IR reflectance spectra of carbonaceous chondrites - I. Implications for remote characterization of dark primitive asteroids targeted by sample-return missions. Mon Not R Astron Soc 437:227-240. Trigo-Rodríguez JM, Alonso-Azcárate J, Abad MM, Lee MR (2015) Ultra high resolution Transmission Electron Microscopy of matrix mineral grains in CM chondrites: preaccretionary or parent body aqueous processing? LPI constribution, 46th LPSC, abstract #1198.

  20. The relationship between ENSO cycle and planetary positions ( Ⅰ): the apparent declination of Jupiter, Saturn and the equatorial eastern Pacific Ocean surface temperature%ENSO循环与行星位置的相互关系(Ⅰ):木星、土星视赤纬与赤道东太平洋海温的联系。

    Institute of Scientific and Technical Information of China (English)

    叶更新; 刘玉清

    2012-01-01

    The monthly Jupiter and Saturn apparent declinations has been calculated by using general astron- omy software SKYMap Pro Version 8, and comparitively studying the ENSO cycle and the key areas of equatorial Pacific sea surface temperature anomalies. The findings were that there was link between the two, namely, as the declination of Jupiter changes from positive through the equator to negative, EL - Nino event is likely to happen and the event duration is longer. Before 1980's this situation happened 3 times corresponding to the case of longer EL- Nino events. After 1980's at the two frequently- occurring stages of EL- Nino,the centers took place dur- ing the Jupiter declination conversion period from positive to negative. EL - Ninos often occur in the vicinity of the declination positive extreme value of Jupiter, and rarely in the negative values. LA - Nnia events tend to occur between the maximum and the equator of the Jupiter declination before 1980g,but after 1980g,it occurred in the vicinity of the negative extreme values of the Jupiter declination The position of Jupiter declination in some EL - Nino events is located in a nearly straight line. Over the past 60 years there have been four such lines. Therefore, the EL - Nino events can be divided into four groups, each group composed of 4 events accurately. When Saturn declination moves towards or away from the equator (in about ± 5°-10°) , EL -Nino occurs, but rarely occurs in the equatorial regions%利用通用天文软件SKYMapProVersion8计算了木星和土星的月视赤纬,将其与ENSO循环及赤道太平洋关键区海温距平进行对比分析,发现两者存在明显联系,主要包括:木星视赤纬由正经过赤道变为负时,容易发生EL-Nino事件,而且事件持续时间较长,1980年代及以前发生过3次这样的情况都对应持续较长的EL-Nino事件,1980年代以后的2次EL-Nino事件群发期,其中心都发生在木星视赤纬从正向负转

  1. X-ray and optical observations of four polars

    Science.gov (United States)

    Worpel, H.; Schwope, A. D.; Granzer, T.; Reinsch, K.; Schwarz, R.; Traulsen, I.

    2016-08-01

    appear to be normal polars with luminosities and magnetic field strengths typical for this class of accreting binary. None of the four systems studied shows the strong soft excess thought commonplace in polars prior to the XMM-Newton era. Based on observations obtained with XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA Member States and NASA.Based on observations collected at the Centro Astronómico Hispano Alemán (CAHA) at Calar Alto, operated jointly by the Max Planck Institut für Astronomie and the Instituto de Astrofísica de Andalucía (CSIC).

  2. Obituary -- Salvador González Bedolla

    Science.gov (United States)

    Peña, H. José

    1997-04-01

    It is with great sadness that I must communicate the passing of our colleague Salvador Félix González Bedolla. The observational astronomers of the Observatorio Astronómico Nacional owe much to his pioneering effort at San Pedro Mártir, work that formed him as an astronomer, and helped him become one of the best photometric observers in México and, at the Instituto de Astronomóa of the UNAM, the academic technician with the highest productivity of articles derived from observations at the OAN. Salvador was an excellent student. He obtained the highest achievement award (Gabino Barreda) in high school, studied physics at the Universidad Nacional Autónoma de México (UNAM) and also finished the credits for his Master's degree in Physics with only his thesis separating him from his degree, an act which was constantly put off until his death. He began his career in Astronomy in 1973 under Dr. Eugenio Mendoza. Later he worked with Josef Warman in the observation of short period stars in the Observatorio `José Arbol y Bonilla'' in Zacatecas, México. I then began working continuously with him in this field of research which, thanks to his great work capacity, produced very good results. He continued in these fields of research not only within the Institute of Astronomy, but also in other research facilities, especially two: With the variable group from the Observatory at Nice, France, beginning in 1985, specializing in the pulsation of early stars. His main interest was in the β Cep stars and in the possibility of relating these stars to the new types of variables (such as the OB stars, the `53 Per' variables, the `ultrashort' period and the ``slow'' and Be variables) discovered near this zone. Hence, in view of this, his efforts were aimed at monitoring the stars that belong to these new groups in order to discover if they are really different from the classical β Cep stars. Moreover, beginning in 1984, Salvador began working with a group of astronomers from

  3. Enceladus' Interior: A Liquid Circulation Model

    Science.gov (United States)

    Matson, Dennis L.; Johnson, Torrence; Lunine, Jonathan; Castillo-Rogez, Julie

    transferred to the near-surface ice. The water is now relatively cold and dense. It absorbs the remaining bubbles and descends via fractures or defects in the ice, and percolates down to the "ocean". The water is in intimate contact with the ice and chemical interactions and heat exchange are possible. While the formation of the briny "ocean" was envisioned as due to the exclusion of non-water chemical species from the ice as it froze [8], a number of mechanisms permit a variety of organic and inorganic species to be present in the ice. The downward percolation of briny water facilitates these by making a large volume of the ice accessible along the crack surfaces. References: [1] J. H. Waite Jr et al., Nature, 460, 487-490 (2009). [2] F. Postberg et al., Nature, 459, 1098-1101 (2009). [3] S. W. Kieffer et al., Science, 314, 1764-1766 (2006). [4] C. Howett, J. R. Spencer, J. Pearl, M. Segura, Bull. Am. Astron. Soc., 41, 1122 (2009). [5] O. Abramov, J. R. Spencer, Icarus, 199, 189-196 (2009). [6] G. D. Crawford, D. J. Stevenson, Icarus, 73, 66-79 (1988). [7] S. L. Murchie, J. W. Head, LPS XVII, 583-584 (1986). [8] M. Y. Zolotov, Geophysical Research Letters, 34, L23203 (2007). This work has been conducted at the Jet Propulsion Laboratory, California Institute of Technology under a contract with the National Aeronautics and Space Administration, and for JIL under the program "Incentivazione alla mobilita' di studiosi straineri italiani residenti all'estero" of Italy.

  4. Isolation of bacteria from Siberian permafrost capable of growing under simulated Mars atmospheric pressure and composition

    Science.gov (United States)

    Nicholson, Wayne; Gilichinsky, David; Schuerger, Andrew; Mironov, Vasiliy; Fajardo-Cavazos, Patricia; Kerney, Krystal; Krivushin, Kirill; Oliveira, Rafael; Waters, Samantha

    a new species, C. gilichinskyi, in honor of the late David Gilichinsky of our team. Additional new isolates from Siberian permafrost capable of growth under low-PTA conditions will be presented. References: [1] Chyba C.F. & Hand K.P. (2005) Annu. Rev. Astron. Astrophys. 43, 31. [2] Jagoutz E. (1991) Space Sci. Rev. 56, 13. [3] Nicholson, W.L. (2009) Trends Microbiol. 17, 243. [4] Nicholson W.L. et al. (2009) Trends Microbiol. 17, 389. [5] Schuerger A.C. (2004) In Martian Expedition Planning, ed Cockell C.S. (Univelt Publishers), 363. [6] Frolov A.D. (2003) JGR-Planets, 108(E4), 7. [7] Nicholson W.L. et al. (2013) Proc. Natl. Acad. Sci USA 110, 666. Acknowledgments: Supported by the following NASA programs: Exobiology and Evolutionary Biology (NNX08AO15G); Planetary Protection (NNA06CB58G); and the Planetary Biology Internship program.

  5. The DiskMass Survey. VI. Gas and stellar kinematics in spiral galaxies from PPak integral-field spectroscopy

    Science.gov (United States)

    Martinsson, Thomas P. K.; Verheijen, Marc A. W.; Westfall, Kyle B.; Bershady, Matthew A.; Schechtman-Rook, Andrew; Andersen, David R.; Swaters, Rob A.

    2013-09-01

    ROiii), with a zero point indicating that galaxy disks are submaximal. Moreover, weak but consistent correlations exist between σz,0/V2.2hROiii and global galaxy properties such that disks with a fainter central surface brightness in bluer and less luminous galaxies of later morphological types are kinematically colder with respect to their rotational velocities. Based on observations collected at the Centro Astronómico Hispano Alemán (CAHA) at Calar Alto, operated jointly by the Max-Planck Institut für Astronomie and the Instituto de Astrofísica de Andalucía (CSIC).Table 2 and Appendices are available in electronic form at http://www.aanda.org

  6. Mal tiempo, tiempo maligno, tiempo de subversión ritual. La temposensitividad agrofestiva invernal

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    Del Campo Tejedor, Alberto

    2006-06-01

    Full Text Available In the light of a number of festive, ritual, poetico-musical and literary expresions, from Andalusia and elsewhere, the author discusses time as lived by agrarian cultures: a syncretic time, resulting from the superposition of civico-political, religious and peasant calendars; a cyclic time, given the effects of astronomico-meteorological time on nature and the subsequent cultural response on both the instrumental dimension (the work in the fields and the expresive dimension (the rituals and the festivals; and, finally, an ages-old bipolar time, experienced as the succession of two alternating seasons —wintertime and summertime—which also underlies a dichotomous agrofestive time-sensitiveness analyzed here under the following hypothesis: during the months of «good weather,» especially May and June, the rituals have a propitiatory and positively extolling sense; they mimetically dramatize the union between earth, vegetation, animals and humans by means of prototypes and archetypes that symbolically recreate the natural order of things. By contrast, the wintertime rituals and festivals—from 1st November till Carnival, and particularly around Christmas—all have in common a grotesque character and a sense of inverted order, symbolically signifying, with a logic at once serio-comic and ambiguous, the dark side of existence, while ritually conjuring up the fears of bad weather, of fateful and pernicious time, the time of cold nights, hunger and death.

    A la luz de algunas expresiones festivas, rituales, poético-musicales y literarias, de Andalucía y otros contextos, el artículo aborda el tiempo vivido por las culturas agroganaderas: un tiempo sincrético, como consecuencia de la superposición de los calendarios civil-político, religioso y campesino; un tiempo cíclico, fruto de la incidencia del tiempo astronómico-meteorológico en la naturaleza y la consiguiente respuesta cultural en el plano instrumental (los trabajos agr

  7. Formation and growth of embryos of the Earth-Moon system

    Science.gov (United States)

    Ipatov, Sergei I.

    2016-07-01

    radius of a considered embryo), and at the growth of the mass of the Earth's embryo by 10 times, the mass of the Moon's embryo increased by a factor of 1.43 and 1.31 at the ratio k_d of the density of the growing Moon to that of the growing Earth equal to its present value (k_d=0.6) and for equal densities (k_d=1), respectively. For the case of small relative velocities of planetesimals, effective radii of the embryos are proportional to r^2, and at the growth of the Earth's embryo mass by 10 times, the Moon's embryo mass increased by a factor of 1.051 and 1.044 at k_d=0.6 and k_d=1, respectively. [1] Galimov E.M., Krivtsov A.M.: Origin of the Moon. New concept. / De Gruyter. Berlin. 2012. 168 p. [2] Ipatov S.I.: Mon. Not. R. Astron. Soc., 2010, vol. 403, pp. 405-414.

  8. FRAM: SHOWERS, COMETS, GRBS AND POPULAR SCIENCE

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    J. Ebr

    2014-01-01

    Full Text Available E l t e l e s c o p i o F R A M , o p e r a d o p o r e l I n s t i t u t o d e F ́ ı s i c a d e l a A c a d e m i a d e C i e n c i a s d e l a R e p ́ u b l i c a C h e c a e s t ́ a u b i c a d o e n e l O b s e r v a t o r i o P i e r r e A u g e r d e A r g e n t i n a . S u o b j e t i v o p r i n c i p a l e s p r o v e e r c a l i b r a c i ́ o n a t m o s f ́ e r i c a a l m e d i r e l c o n t e n i d o d e a e r o s o l y l a s c a r a c t e r ́ ı s t i c a s d e l a a t m ́ o s f e r a s o b r e e l O b s e r v a t o r i o . Y a q u e e s t e p r o g r a m a t o m a s o l o u n a p e q u e ̃ n a p o r c i ́ o n d e l t i e m p o d e o b s e r v a c i ́ o n d i s p o n i b l e , e l t e l e s c o p i o t a m b i ́ e n h a c e s e g u i m i e n t o a una variedad de objetivos astron ́omicos, como GRBs, cometas, asteroides y estrellas variables. Dentro del p r o y e c t o G L O R I A h e m o s d e s a r r o l l a d o u n p r o g r a m a d e d i v u l g a c i ́ o n e x t e n s o , i n c l u y e n d o f r e c u e n t e s a p a r i c i o n e s d e n u e s t r o s r e s u l t a d o s e n l o s m e d i o s p a r a e l p ́ u b l i c o e n g e n e r a l.

  9. Twenty-four-week effects of liraglutide on body composition, adherence to appetite, and lipid profile in overweight and obese patients with type 2 diabetes mellitus

    Directory of Open Access Journals (Sweden)

    Rondanelli M

    2016-03-01

    Full Text Available Mariangela Rondanelli,1 Simone Perna,1 Paolo Astrone,2 Annalisa Grugnetti,2 Sebastiano Bruno Solerte,2 Davide Guido3,4 1Endocrinology and Nutrition Unit, Section of Human Nutrition, Department of Public Health, Experimental and Forensic Medicine, Agency for Elderly People Services, Santa Margherita Hospital, University of Pavia, Pavia, Italy; 2Section of Geriatrics and Gerontology, Department of Internal Medicine, Agency for Elderly People Services, Santa Margherita Hospital, University of Pavia, Pavia, Italy; 3Medical and Genomics Statistics Unit, Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy; 4Biostatistics and Clinical Epidemiology Unit, Department of Public Health, Experimental and Forensic Medicine, University of Pavia, Pavia, Italy Background: Liraglutide has well-known effects on glucose patterns. However, its several other metabolic properties are still controversial. Given this background, the aims of the present study are to evaluate the effects of 24-week liraglutide treatment on body composition, appetite, and lipid profile in overweight and obese type 2 diabetes mellitus (T2DM patients. Methods: A cohort study was carried out on overweight and obese T2DM patients with glycosylated hemoglobin A1c equal to 6% (42 mmol/mol-10% (86 mmol/mol, under a 3-month treatment (at least with maximal dose of metformin as stable regime, by adding liraglutide at doses up to 3 mg/d. Body composition markers were measured by dual-energy X-ray densitometry at baseline and after 24 weeks of liraglutide treatment. Glucose control was monitored by glucose, glycosylated hemoglobin A1c, insulin, and homeostasis model assessment. Finally, the appetite sensation and plasma lipids were also evaluated. Results: Twenty-eight subjects (male/female: 16/12, mean age: 58.75±9.33 years, body mass index: 34.13±5.46 kg/m2 were evaluated. Accounting for the adjustment for age, sex, and duration of diabetes, we noted significant

  10. Nuclear planetology: understanding habitable planets as Galactic bulge stellar remnants (black dwarfs) in a Hertzsprung-Russell (HR) diagram

    Science.gov (United States)

    Roller, Goetz

    2016-04-01

    model constraining the evolution of a rocky planet like Earth or Mercury from a stellar precursor of the oldest population to a Fe-C BLD, shifting through different spectral classes in a HR diagram after massive decompression and tremendous energy losses. In the light of WD/BLD cosmochronology [1], solar system bodies like Earth, Mercury and Moon are regarded as captured interlopers from the Galactic bulge, Earth and Moon possibly representing remnants of an old binary system. Such a preliminary scenario is supported by similar ages obtained from WD's for the Galactic halo [1] and, independently, by means of 187Re-232Th-238U nuclear geochronometry [2, 4, 5], together with recent observations extremely metal-poor stars from the cosmic dawn in the bulge of the Milky Way [6]. This might be further elucidated in the near future by Th/U cosmochronometry based upon a nuclear production ratio Th/U = 0.96 [5] and additionally by means of a newly developed nucleogeochronometric age dating method for stellar spectroscopy, which will be presented in a forthcoming paper. The model shall stimulate geochemical data interpretation from a different perspective to constrain the (thermal) evolution of a habitable planet as to its geo-, bio-, hydro- and atmosphere. [1] Fontaine et al. (2001), Public. Astron. Soc. of the Pacific 113, 409-435. [2] Roller (2015), Abstract T34B-0407, AGU Spring Meeting 2015. [3] Arevalo et al. (2010), Chem. Geol. 271, 70-85. [4] Roller (2015), Geophys. Res. Abstr. 17, EGU2015-2399. [5] Roller (2015), 78th Annu. Meeting Met. Soc., Abstract #5041. [6] Howes et al. (2015), Nature 527, 484-487.

  11. Editorial

    Science.gov (United States)

    Dimitrijevic, M. S.; Popovic, L. C.

    The present issue of SERBIAN ASTRONOMICAL JOURNAL is the last one edited by the two of us. We resigned not because we were tired of our service to the astronomical community but due to the old tradition of the Belgrade Astronomical Observatory that its Director is automatically the Editor-in-Chief of its publications. We therefore gladly give the opportunity to the new Director, in charge since July 1st. 2002, to organize the publishing activity according to his conceptions. One of us (M.S.D.) was appointed Editor on January 1st. 1984 (from No. 135), becoming the Editor-in-Chief in 1987 (from No. 137). The other one (L.C.P.) is the Editor since 1994 (from No. 150). During this period the Bulletin de l'Observatoire Astronomique de Belgrade merged with the Publications of the Department of Astronomy, changing its name into Bulletin Astronomique de Belgrade from No. 145 in 1992, to finally become Serbian Astronomical Journal in 1998, from No. 157. Accordingly, of a "Bulletin" we made a "Journal". For example, in the period 1971-1984 (Nos. 125-134) in Bull. Obs. Astron. Belgrade, practically only the associates of the Belgade Observatory published their papers, save for a few individuals from the Belgrade University. We found within this period the name of one sole foreign astronomer - from the USSR - namely V. A. Fomin, among the authors. In the period 1985-2002 in the Serbian Astronomical Journal published their communications not only astronomers from Yugoslavia but also from Belgium, China, France, Italy, Moldova, Romania, Russia, Spain, Ukraine, USA. Our authors from outside of Yugoslavia are: J. P. Anosova C. Beuyninx Cristina Blaga Paul A. Blaga Veronique Bommier N. M. Bronnikov Alberto Celino Pierre Cugnon D. R. Davis Henry Debehogne Veronique Dehant P. Farinella Alex Gaina R. I. Gumerov R. S. Izmailov V. B. Kapkov F. F. Khalikhevich S. A. Kilioner Tatiana R. Kirian N. G. Litkevich Evencio G. Mediavilla O. Mihai Andrea Milani Vasile Mioc Jose A. Munoz Viktor V

  12. Is the Universe logotropic?

    Science.gov (United States)

    Chavanis, Pierre-Henri

    2015-07-01

    . Not. R. Astron. Soc. 397, 1169 (2009)) where it is found that Σ 0 = 141 M ⊙/pc2 for dark matter halos differing by several orders of magnitude in size. Using this observational result, we obtain B = 3.53 × 10-3. Then, we show that the mass enclosed within a sphere of fixed radius r u = 300 pc has the same value M 300 1.93 × 107 M ⊙ for all the dwarf halos, in agreement with the observations (Strigari et al., Nature 454, 1096 (2008)). Finally, assuming that ρ * = ρ P , where ρ P = 5.16 × 1099 g m-3 is the Planck density, we predict B = 3.53 × 10-3, in perfect agreement with the value obtained from the observations. We approximately have B ≃ 1/ln( ρ P / ρ Λ ˜ 1/[123ln(10)], where 123 is the famous number occurring in the ratio ρ P / ρ Λ ˜ 10123 between the Planck density and the cosmological density. This value of B is sufficiently low to satisfy the cosmological bound 0 ≤ B ≤ 0.09425 and sufficiently large to differ from CDM ( B = 0 and avoid density cusps in dark matter halos. It leads to a Jeans length at the beginning of the matter era of the order of Λ J =40.4 pc which is consistent with the minimum size of dark matter halos observed in the universe. Therefore, a logotropic equation of state is a good candidate to account both for galactic and cosmological observations. This may be a hint that dark matter and dark energy are the manifestation of a single dark fluid. If we assume that the dark fluid is made of a self-interacting scalar field, representing for example Bose-Einstein condensates, we find that the logotropic equation of state arises from the Gross-Pitaevskii equation with an inverted quadratic potential, or from the Klein-Gordon equation with a logarithmic potential. We also relate the logotropic equation of state to Tsallis generalized thermodynamics and to the Cardassian model motivated by the existence of extra-dimensions.

  13. Efectos difusivos en la formación de enanas blancas de Helio de baja masa en sistemas binarios cerrados

    Science.gov (United States)

    De Vito, M. A.; Benvenuto, O. G.

    In the last years, and thanks to advances in observational techniques, many astronomers have discovered in a great number of binary radio-pulsars the presence of a helium white dwarf resulting from a previous evolutionary state in which the progenitor of this star experienced one or more episodes of mass transfer to the compact component in the pair. That is the case for PSR B1855+09 (van Kerkwijk, M. H., Bell, J. F, Kaspi, V. M., & Kulkarni, S. R. 2000, ApJ 530, L37), where the mass for the white dwarf is known accurately from measurements of the Shapiro delay of the pulsar signal, MWD = 0.258+0.028-0.016 M⊙; for PSR J02018 + 4232 (Bassa, C. G., van Kerkwijk, M. H., & Kulkarni, S. R. 2003, A&A, 403, 1067), the spectra confirm that the companion is a helium-core white dwarf of ≈ 0.2 M⊙. On the other hand, there are several authors (Ferraro, F., Possenti, A., Sabbi, E., & D'Amico, N. 2003, ApJ, 596, L211; Bassa et al. 2003) that have identified the optical binary companion to the BMSP PSR J1911 - 5958A, located in the halo of the Galactic globular cluster NGC 6752, like a blue star whose position in the color-magnitude diagram is consistent with the cooling sequence of a low-mass, ≈ 0.17 - 0.20 M⊙, low metallicity helium white dwarf at the cluster distance. Finally, the color and magnitude of the stellar companion for B 1620-26 indicate that is a white dwarf of 0.34 ± 0.04 M⊙ (Sigurdson, S., Richer, H. B., Hansen, B. M., Stairs, I. H. & Thorset, S. E. 2003, Science, 301, 193S). This has motivated us to study the formation of low mass helium white dwarfs in the context of binary evolution. For that purpose, using the code of binary evolution, entirely developed in the Facultad de Ciencias Astronómicas y Geofísicas of the Universidad Nacional de La Plata, Argentina, we have investigated the effects of diffusive processes on the evolution of a star member of a close binary system. A similar study was performed for Althaus, L. G., Serenelli, A. M

  14. Searching for signatures of planet formation in stars with circumstellar debris discs

    Science.gov (United States)

    Maldonado, J.; Eiroa, C.; Villaver, E.; Montesinos, B.; Mora, A.

    2015-07-01

    derived slopes is low, however, probably because of the wide range of stellar parameters of our samples. Stars hosting exclusively close-in giant planets behave in a different way, showing higher metallicities and positive ⟨[ X/Fe ] ⟩ - TC slope. A search for correlations between the ⟨[ X/Fe ] ⟩ - TC slopes and the stellar properties reveals a moderate but significant correlation with the stellar radius and a weak correlation with the stellar age, which remain even if Galactic chemical evolution effects are considered. No correlation between the ⟨[ X/Fe ] ⟩ - TC slopes and the disc/planet properties are found. Conclusions: The fact that stars with debris discs and stars with low-mass planets do not show either metal enhancement or a different ⟨[ X/Fe ] ⟩ - TC trend might indicate a correlation between the presence of debris discs and the presence of low-mass planets. We extend results from previous works based mainly on solar analogues with reported differences in the ⟨[ X/Fe ] ⟩ - TC trends between planet hosts and non-hosts to a wider range of parameters. However, these differences tend to be present only when the star hosts a cool distant planet and not in stars hosting exclusively low-mass planets. The interpretation of these differences as a signature of planetary formation should be considered with caution since moderate correlations between the TC-slopes with the stellar radius and the stellar age are found, suggesting that an evolutionary effect might be at work. 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); observations made with the Italian Telescopio Nazionale Galileo (TNG) operated on the island of La Palma by the Fundación Galileo Galilei of the INAF (Istituto Nazionale di Astrofisica); observations made with the Nordic Optical Telescope, operated on the island of La Palma

  15. A Look into the Hellish Cradles of Suns and Solar Systems

    Science.gov (United States)

    2009-09-01

    Rose, T.L. Bourke, R.A. Gutermuth and S.J. Wolk (Harvard-Smithsonian Center for Astrophysics, Cambridge, USA), S.T. Megeath (Department of Physics and Astronomy, The University of Toledo, USA), J. Alves (Centro Astronómico Hispano Alemán, Almeria, Spain), and D. Nürnberger (ESO). ESO, the European Southern Observatory, is the foremost intergovernmental astronomy organisation in Europe and the world's most productive astronomical observatory. It is supported by 14 countries: Austria, Belgium, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland and the United Kingdom. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world's most advanced visible-light astronomical observatory. ESO is the European partner of a revolutionary astronomical telescope ALMA, the largest astronomical project in existence. ESO is currently planning a 42-metre European Extremely Large optical/near-infrared Telescope, the E-ELT, which will become "the world's biggest eye on the sky".

  16. Poluição atmosférica e atendimentos por pneumonia e gripe em São Paulo, Brasil Air pollution and emergency room visits due to pneumonia and influenza in São Paulo, Brazil

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    Lourdes Conceição Martins

    2002-02-01

    Full Text Available OBJETIVO: Investigar os efeitos causados pela poluição atmosférica na morbidade por pneumonia e por gripe em idosos entre 1996 e 1998. MÉTODOS: Foram obtidos dados diários de atendimentos por pneumonia e gripe para idosos em pronto-socorro médico de um hospital-escola de referência no Município de São Paulo, SP, Brasil. Os níveis diários de CO, O3, SO2, NO2 e PM10 foram obtidos na Companhia de Tecnologia de Saneamento Ambiental, e os dados diários de temperatura e umidade relativa do ar foram obtidos no Instituto Astronômico e Geofísico da USP. Para verificar a relação existente entre pneumonia e gripe e poluição atmosférica, utilizou-se o modelo aditivo generalizado de regressão de Poisson, tendo como variável dependente o número diário de atendimentos por pneumonia e gripe e como variáveis independentes as concentrações médias diárias dos poluentes atmosféricos. A análise foi ajustada para sazonalidade de longa duração (número de dias transcorridos, sazonalidade de curta duração (dias da semana, temperatura mínima, umidade média, períodos de rodízio e os atendimentos por doenças não-respiratórias em idosos. RESULTADOS: O3 e SO2 estão diretamente associados à pneumonia e à gripe, independentemente das variáveis de controle. Porém, na análise conjunta, eles perdem sua significância estatística. Pôde-se observar que um aumento interquartil (25%-75% para o O3 (38,80 mig/m³ e SO2 (15,05 mig/m³ levaram a um acréscimo de 8,07% e 14,51%, respectivamente, no número de atendimentos por pneumonia e gripe em idosos. CONCLUSÕES: Os resultados sugerem que a poluição atmosférica promove efeitos adversos para a saúde de idosos.OBJECTIVE: A time series was developed to investigate the effect of air pollution levels on morbidity due to respiratory diseases such as pneumonia and influenza among elderly people from 1996 to 1998. METHODS: Daily data on emergency room visits was collected at the university

  17. NEW WEB TECHNOLOGIES FOR ASTRONOMY

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    P-G. Sprimont

    2014-01-01

    Full Text Available G r a c i a s a l a s n u e v a s c a p a c i d a d e s d e H T M L 5 , y l a s g r a n d e s m e j o r a s d e l l e n g u a j e J a v a S c r i p t e s p o s i b l e d i s e ̃ n a r i n t e r f a c e s w e b m u y c o m p l e j a s e i n t e r a c t i v a s . A d e m ́ a s , l o s s e r v i d o r e s q u e e r a n u n a v e z m o n o l ́ ı t i c o s y o r i e n t a d o s a s e r v i r a r c h i v o s , e s t ́ a n e v o l u c i o n a n d o a a p l i c a c i o n e s d e s e r v i d o r f ́ a c i l m e n t e p r o g r a m a b l e s , c a p a c e s d e l i d i a r con interacciones complejas gracias a la nueva generaci ́on de navegadores. Nosotros creemos que la comunidad d e a s t r ́ o n o m o s p r o f e s i o n a l e s y a fi c i o n a d o s e n t e r a p u e d e b e n e fi c i a r s e d e l p o t e n c i a l d e e s t a s n u e v a s t e c n o l o g ́ ı a s . N u e v a s i n t e r f a c e s w e b p u e d e n s e r d i s e ̃ n a d a s p a r a p r o v e e r a l u s u a r i o c o n h e r r a m i e n t a s m u c h o m ́ a s i n t u i t i v a s e interactivas. Acceder a archivos de datos astron ́omicos, controlar y monitorear observatorios y en particu- l a r t e l e s c o p i o s r o b ́ o t i c o s , s u p e r v i s a r p i p e l i n e s d e r e d u c c i ́ o n d e d a t o s , s o n t o d a s c a p a c i d a d e s q u e p u e d e n s e r imp l e m e n t a d a s e n u n a a p l i c a c i ́ o n w e b J a v a S c r i p t . D e s c r i b i m o s e l p a q u e t e Sadira que estamos implementando exactamente con este prop ́osito.

  18. A proposed contents astronomy for basic education

    Science.gov (United States)

    Albrecht, E.; Voelzke, M. R.

    2014-08-01

    A Astronomia é um tema que sempre exerceu fascínio sobre as pessoas de um modo geral. Conhecer e estudar o que há nos “céus”, além de nossos olhos, continua sendo instigador e de grande interesse. Baseado nestas justificativas desenvolveu-se uma pesquisa de Doutorado, na qual, o objetivo principal foi investigar sobre a presença dos conteúdos de Astronomia nas Propostas Curriculares da região Sul do Brasil, a saber, os estados de Paraná, Rio Grande do Sul e Santa Catarina e, posterior comparação com os Parâmetros Curriculares Nacionais (PCN) que trazem propostas de conteúdos para toda a Educação Básica brasileira. Tal investigação pautou-se na abordagem de caráter qualitativo e utilizouse para tal da Análise de Conteúdos (Bardin, 2011), que possibilitou a construção de quatro categorias, nas quais os conteúdos astronômicos foram agrupados: Terra, Sistema Solar, Via Láctea e Universo. Após a leitura, coleta de dados, construção de categorias, observou-se a dicotomia na apresentação destes conteúdos. As propostas curriculares analisadas foram as de Geografia, Ciências e Física dos estados do Paraná (2008), Rio Grande do Sul (2009) e de Santa Catarina (1998), responsáveis pelo trabalho com Astronomia nestes estados. No Ensino Fundamental, a proposta curricular do estado do Paraná apresenta conteúdos ligados à Astronomia desde o sexto ano até o nono ano, como conteúdo do primeiro bimestre, o que também é apresentado na proposta curricular do estado do Rio Grande do Sul, porém, este, não divide os conteúdos por bimestre e nem por ano, mas por ciclos, sexto e sétimo anos como primeiro ciclo e oitavo e nono anos como segundo ciclo, deixando livre para o professor estruturar sua sequência de conteúdos. A proposta curricular de Santa Catarina não apresenta estes conteúdos de maneira explícita, não divide dos conteúdos nem por ano, nem por série, traz uma sequência de conteúdos para serem trabalhados ao longo dos

  19. Do Carbynes Exist as Interstellar Material After All?

    Science.gov (United States)

    Gilkes, K. W. R.; Gaskell, P. H.; Russell, S. S.; Arden, J. W.; Pillinger, C. T.

    1992-07-01

    216, 984-986. Kasatochkin V. I., Sladkov A. M., Kudryaytsev, Popov N. M., and Korshak V. V., Dokl. Acad. Nauk. SSSR, 177, 358-360. Lewis R. S., Ming T., Walker J. F., Anders E., and Steel E. (1987) Nature 326, 160-164. Russell S. S., Arden J. W., and Pillinger C. T. (1991) Science 254, 1188-1191. Smith P. P. K. and Buseck P. R. (1982) Science 216, 984-986. Webster A. S. (1980) Mon. Not. R. Astron. Soc. 192, 7P-9P. Whittaker A. G., Watts E. J., Lewis R. S., and Anders E. (1980) Science 209, 1512-1514.

  20. On the roto-translatory internal motions of a three layer non-isobarycentric Earth model: a Lagrangian system approach

    Science.gov (United States)

    Escapa, Alberto; Fukushima, Toshio

    2010-05-01

    simply a kinematical correction on the degenerate mode of a non-rotating model. Namely, the relative errors in the periods of the equatorial modes are reduced from 11.69% to 3.79% and from -6.04% to -1.91%, respectively. Acknowledgement.- AE's contribution was carried out thanks to a sabbatical leave from the University of Alicante at the National Astronomical Observatory of Japan (NAOJ), supported by the Spanish Ministerio de Educación, project PR2009-0379, within the Programa Nacional de Movilidad de Recursos Humanos I-D+i 2008-2011. The generous hospitality of the NAOJ staff is gratefully acknowledged. References Busse, F.H., J. Geophys. Res. 79, 753, 1974 Getino, J. and Ferrándiz, J. M., Mon. Not. R. Astron. Soc. 322, 785, 2001 Moritz, H., Bull. Géod., 56, 364, 1982 Rieutord, M., Phys. Earth Planet. Int., 131, 269, 2002