Instituto de Astrofísica de Andalucía
Seminarios impartidos durante 2001
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Instituto de Astrofísica de AndalucíaSeminarios impartidos durante 2001 |
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7 de Noviembre
Dr. José María Torrelles
Instituto Estudios Espaciales de Cataluņa.
Enigmática expulsión esférica de materia en un embrión estelar.
ALMA, una gran espectativa.
6 de Noviembre
Dr. Simon Pustilnik
Astrophysical Observatory, Rusia
(The Hamburg/SAO survey for low metallicity BCGs (HSS-LM)).
The description and the first results of the new project will be presented. It is devoted to the search for the most metal-deficient blue compact galaxies. The first goal is to extend the sample of the most interesting candidates to truly young galaxies in the local Universe, and study them in detail. The second goal of the project is to create a large, clearly selected sample of BCGs with reliably measured O/H. The data will be used for the statistical analysis of metallicity along with the global galaxy parameters and its environment. They will be used to confront the observed relationships with model predictions.
24 de Octubre
Dra. Matilde Fernandez (IAA)
Acreción y pérdida de masa cerca del límite subestelar
LS-RCrA 1 es una estrella de tipo espectral muy tardío (M6.5-M7) cuyo espectro muestra líneas de emisión muy intensas, tanto prohibidas como permitidas. La estrella parece encontrarse en una región de formación estelar, lo que explicaría la presencia de las líneas, pero su posición en el diagrama HR, teniendo en cuenta las trazas evolutivas calculadas para estrellas de muy baja masa, difiere de la esperada.
24 de Octubre
Dra. Matilde Fernandez (IAA)
Acrecion y pérdida de masa cerca del límite subestelar
LS-RCrA 1 es una estrella de tipo espectral muy tardío (M6.5-M7) cuyo espectro muestra líneas de emisión muy intensas, tanto prohibidas como permitidas. La estrella parece encontrarse en una región de formación estelar, lo que explicaría la presencia de las líneas, pero su posición en el diagrama HR, teniendo en cuenta las trazas evolutivas calculadas para estrellas de muy baja masa, difiere de la esperada.
2 de Octubre
Dr. Stefan Gottloeber (IAP-Postdam)
The evolution of galaxies in different cosmological environment
According to the hierarchical scenario, galaxies form via merging and accretion of small objects. Within a series of high resolution simulations we have studied the formation and evolution of dark matter halos hosting galaxies. First halos have been formed at z > 10. We have studied the evolution of isolated halos (field galaxies) as well as of halos in dense regions (galaxies in groups or clusters and galaxies with satellites) and of small halos in voids. At z < 2 the merging rate of the overall halo population can be described by a simple power law $(1+z)^3$. Halos located at present inside clusters have formed earlier than isolated halos of the same mass. At low redshifts (z<1), their merger rate is 3 times lower than that of isolated halos and 2 times lower than the merger rate of halos that end up in groups by z=0. At higher redshifts (z>1), progenitors of cluster and group halos have 3--5 times higher merger rates than isolated halos. Subsamples of halos with different merging histories show different clustering properties.
26 de Septiembre
Dr. Antxon Alberdi IAA
Perspectivas científicas con VLBI a longitudes de onda milimétricas
12 de Septiembre
Dr. Gregorio Molina (IAA)
Interacción de meteoroides con las atmóferas de Marte y Titán.
4 de Julio
Dr. Rafael Rodrigo
(IAA)
El instrumento OSIRIS de la misión Rosetta.
28 de Junio
Prof. Alexander Zhuk (IMAFF)
The problem of stability of internal spaces in multidimensional
cosmology.
We investigate effective 4-dimensional theories which were obtained under dimensional reduction of multidimensional cosmological models. We show that for warped product spacetimes the conformal (geometrical moduli) excitations of the internal spaces should be observable as massive scalar fields in the external (our) spacetime. These scalar fields (gravitational excitons) describe weakly interacting particles and can be considered as dark matter components. An essential role is played by the effective potential. On the one hand, its minima fix possible stabilization scales of the internal spaces, on the other hand, they provide possible values for the effective cosmological constant.
27 de Junio
Prof. Alan Marscher (Institute for Astrophysical Research,
Boston University)
High-Energy Emission from Relativistic Jets in Blazars.
We have been observing a number of blazars with the Very Long Baseline Array in concert with monitoring at other wavebands, including X-rays and gamma-rays. Observations over several years demonstrate that there is an intimate connection between the ejection of apparent superluminal knots in the relativistic jets and X-ray or gamma-ray flares in blazars. The high-energy emission tends to be simultaneous with or even to follow the radio event, which leads to the surprising conclusion that all the highly variable emission comes from the radio-emitting part of the jet, which lies at distances of parsecs from the supermassive black hole. In the radio galaxy 3C 120, an X-ray dip precedes the ejection of each superluminal feature, similar to what is seen in the "microquasar" GRS 1915+105 in our Galaxy.
26 de Junio
Dr. Olivier Witasse (Space Science Department of ESA, Estec)
Some aspects of the upper atmosphere of Mars: ionosphere,
airglow, meteors.
The comparative study of the planetary atmospheres is a young and interesting science, because of the diversity of the situations. As part of this programme, the exploration of Mars is very challenging. This talk concerns more particularly the modeling of the Martian ionosphere, in the context of the future missions to Mars (Mars-Express, Nozomi, Netlander, Mars 2007). The ionospheric model is based on a terrestrial coupled kinetic and fluid model. I will present the main outputs of the model, including some UV airglow calculation. In a second part, I will talk about another source for the ionosphere, namely the meteors, in the context of the collaboration with Gregorio Molina Cuberos.
22 de Junio
D. José Luis Jaramillo (IAA)
Panorama de la Gravedad Cuántica.
El objetivo fundamental de esta charla es promover un acercamiento entre las comunidades observacional y teórica de este Instituto. Con la sensibilización como meta previa, se realizará un recorrido por la situación actual de la investigación en Gravedad Cuántica, enfatizando los aspectos conceptuales de las principales aproximaciones al problema y motivando las correspondientes soluciones técnicas.
13 de Junio
Dr. Víctor Aldaya (IAA)
Unificación no trivial de las fuerzas electromanéticas y gravitatorias.
El principio de mínima interacción es revisado en un marco grupoteórico. Al imponer la invariancia "local" bajo traslaciones espaciotemporales del lagrangiano de la partícula libre después de haber extendido centralmente el grupo de Poincare por U(1) (invariancia de fase en Mecánica Cuántica) aparece una nueva fuerza de tipo electromagnético pero de origen puramente gravitatorio. Esto constituye un paso hacia la mezcla de simetrías gauge espaciotemporales y unitarias, y con ello de las correspondientes interacciones.
En esta charla se hará una revisión del concepto de corrugación como fenómeno universal que afecta a los discos de las galaxias espirales y se plantean diversas estrategias para dirimir su origen y estructura.
23 de Mayo
Dr. Bernd Funke (IAA)
Retrieval of atmospheric parameters from MIPAS/ENVISAT emission
spectra at 5.3 um under non-LTE conditions.
In (hopefully) 5 months ESA's polar platform ENVISAT will be launched. The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) is one of the core instruments and will continously record high resolution emission spectra of the Earth's atmosphere. Vertical profiles of temperature and various trace gases relevant to stratospheric chemistry are planned to be retrieved from the data. The talk will give a summary on the status of the algorithm development for the MIPAS data analysis carried out at IAA and IMK (Institut fuer Meteorologie und Klimaforschung, Germany). A main task of these activities at IAA is the correct treatment of non-local thermodynamic equilibrium (non-LTE) in the retrieval of atmospheric parameters. Non-LTE specific problems in the MIPAS data analysis and their solutions will be discussed by the example of the atmospheric parameter retrieval from the 5.3 um region of the NO fundamental band.
18 de Mayo
Prof. Malvin Ruderman (IAA)
Evolution of Pulsar Magnetic Fields.
Because canonical neutron stars consist mainly of superfluid neutrons, superconducting protons and extremely relativistic electrons, all enclosed by a thin solid crust, the magnetic field structures of these stars vary in predictable ways during stellar spin-up and spin-down. Predicted consequences will be compared to a variety of observations of regular and millisecond pulsars including sudden changes in pulsar spin-periods ("glitches") and very slow oscillations of them ("precession"?).
9 de Mayo
Dr. Fernando Moreno (IAA)
Procesos de "scattering" múltiple en comas cometarias.
Los modelos dinámicos multifluido realizados hasta la fecha para el cálculo de la distribución de gas y polvo en las comas cometarias rodeando núcleos no esféricos no tienen en cuenta el efecto del "scattering" múltiple de la luz solar por las partículas que rodean al cometa. Nuestras estimaciones indican, sin embargo, que la profundidad óptica en el visible en condiciones subsolares, en las comas de ciertos cometas con elevado contenido en polvo como Halley o Hale-Bopp, a distancias heliocéntricas del orden de 1 AU estarían en torno a 1-2, por lo que los procesos de "scattering" multiple no son en absoluto despreciables. Además, hay que incluir el flujo reradiado en el infrarrojo por las partículas como contribución al flujo total que llega al núcleo. En esta charla se describe el código de Monte-Carlo que hemos desarrollado para estos cálculos, que incluye asimismo el cálculo del vector de Stokes de la luz emergente, permitiendo una comparación con las medidas de polarización realizadas hasta la fecha, para lo cual hemos usado las matrices de "scattering" obtenidas en el laboratorio para ciertos componentes cometarios como la olivina.
2 Mayo
Dr. Robert Haberle (Space Science Division - NASA Ames
Research Center)
Recent Water Activity on the Surface of Mars
There are two known reservoirs of water on Mars: the atmosphere, and the north polar cap. The latter contains possibly as much as 10 meters of water (global ocean equivalent). What happens to this water at high obliquity? Mars' obliquity varies chaotically on time scales greater than 10 million years and may have been as high as 60 degrees. We use a general circulation model with a simple hydrological cycle to address this question. We find that large ice sheets can build up in non polar regions at high obliquity. These results may help explain the puzzling observations of putative lakes, glaciers, and other ice-related features that seem to have existed in the relatively recent geological past.
24 Abril
Prof.Dr. Stephen Hawking (Lucasian Professor, Cambridge University)
Seminario-coloquio
18 Abril
Dr. Vicent Martinez (Observatori Astronomic de la Universitat de Valencia)
Is the universe fractal or homogeneous on large scales?
The debate about the possible smoothness of the Universe on large scales as opposed to an unbounded fractal hierarchy has been the subject of increasing interest in recent years. The controversy arises as a consequence of different statistical analyses performed on surveys of galaxy redshifts. I review the observational evidence supporting the idea that a gradual transition occurs in the galaxy distribution: from a fractal regime at small scales to large scale homogeneity.
4 Abril
Dr. Yuri N. Efremov (Sternberg Astronomical Institute
Moscow State University)
Arc-shaped star complexes in galaxies
There exist isolated star complexes , located sometimes far away from the center of a galaxy or from the spiral arms. These complexes often have spheroidal or arc-like shapes. The best examples are in the LMC, NGC 6946 and NGC 5236. This shape strongly suggests triggering by some energetic events. The striking feature of these complexes is their sharp and circular outer edge. This suggests they are partiall spheres and could be formed from the gaseous supershells. The nature of the events triggered the formation of supershells and more so of these peculiar complexes is the controversial issue.
21 Marzo
Dr. Jack Sulentic (University of Alabama)
Stephan's Quintet: Anatomy of a Multiple Galaxy Collision.
We present old and new unpublished multiwavelength data for the most famous compact group of galaxies. Such groups are ideal laboratories for studying the effects of strong interactions. The data suggest an evolutionary history that may have general relevance to the compact group phenomenon and to interaction phenomena in the early Universe. The data suggest that SQ has been visited by two intruders in the past Gyr. The first intruder stripped the individual galaxy ISMs which has supressed star formation and given rise to a diffuse halo. The ongoing high velocity intrusion is responsible for an X-ray shock. The data support the hypothesis that compact groups merge much more slowly than predicted by many dynamical models.
16 Marzo
Prof. José Cernicharo (IMAFF, CSIC)
Moléculas y anillos aromáticos en el espacio.
8 Marzo
Leonel Gutierrez (Observatorio Astronómico Nacional. UNAM)
Un método para la alineación del telescopio de 1.5m de San Pedro Mártir
7 Marzo
Arno Riffeser (University of Munich)
WeCAPP: Wendelstein Calar Alto Pixellensing Project:
Capturing dark matter in M31
I present (WeCAPP) our long time project searching for microlensing events in M31. Since 1997 the bulge of M31 was monitored in two different wavebands with the Wendelstein 0.8 m telescope. In 1999 we extended our observations to the Calar Alto 1.23m telescope. Observing simultaneously on these two sites we obtained a larger than 60% time coverage of the visibility of M31. To check thousands of frames for variability of unresolved sources, we used the image subtraction method proposed by Alard & Lupton (1998). With this method we were able to minimize the residuals in the difference image analysis (Tomaney & Crotts 1996) and to detect sources with an amplitude near the photon noise level. With the expected microlensing events and their timescales, it will be possible to favour or rule out a certain MACHO population and to derive constraints for the dark matter compound of M31.
21 Febrero
Dr. José Carlos del Toro (Instituto de Astrofísica
de Andalucía, CSIC)
El campo magnético de las manchas solares
En esta charla trataré de repasar y resumir nuestros conocimientos más actuales acerca del campo magnético de las manchas, de su estructura tridimensional, del transporte energético a través de su atmósfera, así como de las relaciones del campo magnético con los fenómenos dinámicos más importantes que tienen lugar en la fotosfera de las manchas.
Most Active Galactic Nuclei (AGN) are characterized by the presence of broad emission lines. However the AGN definition includes a wide range of phenomenologies, both radio-loud and radio-quiet. We report on exciting new developments that unify all classes of AGN showing broad lines. Correlations in this "Eigenvector 1" parameter space appear to be driven primarily by the accretion rate onto the supermassive black holes that power these sources.
En la eyección de muchos de los flujos colimados observados las nebulosas planetarias parecen estar involucradas estrellas binarias. Sin embargo, el número de estrellas centrales binarias que se conocen
es escaso y la detección de binarias puede ser difícil observacionalmente. Una forma de inferir la presencia
de una estrella central binaria es estudiar su influencia en las propiedades nebulares. Presentamos dos nebulosas planetarias (IC4846 y Hu2-1) en las que se observan diferencias claras entre la velocidad
sistémica de la envoltura principal y la velocidad sistémica de los flujos colimados. Esta diferencia se
considera una evidencia directa de binariedad en la estrella central. Los parámetros orbitales que se
obtienen a partir de la cinemática relacionan las estrellas centrales de IC4846 y Hu2-1 con binarias interactuantes y sugieren que los flujos colimados se generan en un disco de acrecimiento alrededor de
una compañera.
En Abril de 2002 está previsto el lanzamiento de la misión INTEGRAL de la ESA, que operará durante
al menos 5 años cubriendo todo el rango desde los 3 keV hasta los 10 MeV, con una sensibilidad sin
precedentes a Altas Energías, lo que permitirá investigar nuevos fenómenos violentos en el Universo. Las
propuestas para el Primer Anuncio de Oportunidad se han de presentar antes del 16 de Febrero de 2001.
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