List of all the talks in the archive, sorted by date.
Visión global de todas las fases que sigue el ciclo de vida de un proyecto aeroespacial.
A la hora de diseñar un satélite debemos considerarlo como parte de un sistema más grande compuesto por el segmento Tierra, el lanzador y por último el segmento espacio. El diseño de un satélite estará determinado por el tipo de misión que realizará, su presupuesto y duración; por el lanzador, su modo y trayectoria de lanzamiento; por los materiales y piezas a usar y su vida útil; por la estación en Tierra; etc. En esta charla se hace un breve resumen de los elementos que forman parte del segmento Tierra y del lanzador y se habla más extensamente del satélite, i.e. la plataforma y la carga útil.
La primera parte de la charla está dedicada a una introducción a las misiones espaciales, presentando una breve perspectiva histórica de los casi 60 años de vida de la exploración espacial, junto con un análisis de los retos y tendencias actuales asociados al auge de los satélites de pequeño tamaño. La segunda parte de la charla está dedicada al análisis de las condiciones extremas de operación en el espacio y sus efectos sobre la intrumentación, incidiendo especialmente en los efectos de la radiación sobre los sistemas electrónicos.
Presentación del curso "Introducción a la instrumentación para satélites de observación de la Tierra" por parte de Pablo Redondo y Alex Ozcoz.
The Universe’s largest galaxy clusters likely built the majority of their massive >10^11 M⊙ galaxies in simultaneous, short-lived bursts of activity well before virialization. The most challenging observational hurdle in identifying such pre-virialized “protoclusters” is their very large volumes, ~10^4 comoving Mpc^3 at z > 2, subtending areas ~half a degree on the sky. Thus the contrast afforded by an overabundance of very rare galaxies in comparison to the background can more easily distinguish overdense structures from the surrounding, normal density field. There are now five well-known 2 < z < 3 proto-clusters from the literature which are found to contain up to 12 dusty starbursts or luminous AGN galaxies each, a phenomenon that is unlikely to occur by chance even in overdense environments. I will discuss these in addition to some higher-redshift (4 < z < 5.5) groups, whose evolutionary fate is less clear. Measurements of DSFGs’ gas depletion times suggest that they are indeed short-lived on ~100 Myr timescales, and accordingly the probability of finding a structure containing more than 8 such systems is 0.2%, unless their ‘triggering’ is correlated on very large spatial scales, ~10 Mpc across. The volume density of DSFG-rich protoclusters is found to be comparable to all >10^15 M⊙ galaxy clusters in the nearby Universe, a factor of five larger than expected in some simulations. Some tension yet exists between measurements and simulations. However, improved observations of protoclusters over large regions of sky will certainly shed more light on the assembly of galaxy clusters, thus fundamental parameters governing cosmology, and also the role of environment in shaping the formation and evolution of galaxies.
ALMA is a submillimetre/millimetre telescope located at 5000m in the Atacama desert in Chile designed to observe at 0.32–9.5 mm (31–950 GHz), and it is expected to be the leading observatory in these wavelengths for many decades to come. ALMA has performed scientific observations since September 2011, with new capabilities being offered for each new observing cycle. The interface between ALMA and the astronomical community is provided by the ALMA Regional Centres (ARCs). The European ARC is located at ESO, Garching. In Europe, the services to the community are provided by a distributed network of ARC nodes. The European ARC network is an international, geographically dispersed structure, and consists of the central ARC at ESO, seven ARC nodes and one Centre of Expertise, distributed across Europe. It is an organised effort to provide the European ALMA user community with uniform expert support from the stage of proposal preparation through to data reduction, in order to enable the optimal usage and increase the scientific output of ALMA. The model for the European ARC nodes network will be described in terms of its organisation, communication strategies and user support. ALMA capabilities and recent ALMA results will also be summarised.
Depending on the interest of the participants, the talk can be followed by a small demo of the ALMA Observing Tool (OT) for the creation and submission of ALMA proposals, as well as the ALMA Snooping Project Interface (SnooPI), that allows PIs and Co-Is to follow their projects throughout their life-cycle.
According to standard evolutionary theory, cataclysmic variables (CV) evolve from longer to shorter orbital periods until a minimum period P_min is reached.
The period bouncers are such CVs that have passed beyond P_min and are evolving back toward longer periods, with the donor star now extremely dim.
This has long been predicted to be the "graveyard" and current state of 70% of all CVs, though only about a dozen of more or less robust candidates for
such period bouncer systems have been identified until now, out of a thousand of known CVs.
In this talk I will discuss the various methods by which such post period-minimum CVs can be recognized, and will also highlight recent progress in this field.
I will address the question of the formation of the first generations of stars in the Local Group dwarf spheroidal galaxies as well as in the Milky Way halo. I will outline our latest news on the observational front focussing on the dispersion (or not) in abundance ratios, discuss LTE and NLTE treatments of the elemental abundances, and present how high resolution numerical simulations can help us understand the onset of the galaxy star formation histories.
Models of the Thermally Pulsing Asymptotic Giant Branch (TP-AGB) stellar evolutionary phase play a critical role across astrophysics, from the chemical composition of meteorites in the pre-solar nebula up to galaxy evolution in the high-redshift Universe. In spite of its importance, the modelling of TP-AGB is still affected by large uncertainties which propagate into the field of extragalactic astronomy, impinging on the predicting power of current population synthesis models of galaxies in terms of their basic properties such as ages, masses and chemical enrichment. In this context I will review recent advances and ongoing efforts toward a physically-sound TP-AGB calibration that, moving beyond the classical use of the Magellanic Cloud clusters, combines increasingly refined TP-AGB stellar models with exceptionally high-quality data for resolved TP-AGB stars in nearby galaxies.
The lack of detection of elementary particles that could explain dark matter and the recent detection of gravitational waves by the LIGO experiment have renewed interest in the hypothesis that dark matter can be made of Primordial Massive Black Holes (PMBH). We review very briefly the outcomes and limits of the classical MACHO experiment, used to probe the dark matter in the halo of the Milky Way from galactic microlensing, and introduce the more universal scenario of quasar microlensing. Quasar microlensing is sensitive to any population of compact objects in the lens galaxy, to their abundance and to their mass. Using microlensing data from 24 lensed quasars, we conclude that the fraction of mass in any type of MACHO is negligible outside of the 0.05 MSun<M<0.45 MSun mass range. This excludes any significant population of intermediate mass PBH. We estimate a fraction of halo mass in microlenses of 20%. The range of masses and abundances are in agreement with those expected for the stellar component. Using the mean mass estimate and some limits derived from multiwavelength microlensing observations we speculate about the stellar Present Day Mass Function.
- TODAY: The Pristine survey: An efficient search for extremely metal-poor starsDr. Kris YouakimTuesday January 23, 2018 - 12:30
- On the evolution of rotation and magnetism from solar-like stars to red giants using Kepler dataDr. Savita MathurThursday February 1, 2018 - 10:30