Found 26 talks archived in Catalogs and data
IAC
Abstract
We present the new stellar population synthesis models based on the empirical stellar spectral library MILES, which can be regarded nowadays as standard in the field of stellar population studies. The synthetic SEDs cover the whole optical range at resolution 2.3 Å (FWHM). The unprecedented stellar parameter coverage of MILES allowed us to extend our model predictions from intermediate- to very-old age regimes, and the metallicity coverage from super-solar to [M/H] = -2.3. Observed spectra can be studied by means of full spectrum fitting or line-strengths. For the latter we propose a new Line Index System (LIS) to avoid the intrinsic uncertainties associated with the popular Lick/IDS system and provide more appropriate, uniform, spectral resolution. We present a web-page with a suite of on-line tools to facilitate the handling and transformation of the spectra. Online examples with practical applications to work with stellar spectra for a variety of instrumental setups will be shown. Furthermore we will also show examples of how to compute spectra and colors with varying instrumental setup, redshift and velocity dispersion for a suite of Star Formation Histories.
Abstract
The current databases of empirical star spectra for modelling single-aged stellar populations (SSPs) generally do not chemically characterize their stars completely. Spectral properties of stars and their populations may change considerably if the elemental abundance ratios E/Fe differ from the solar-scaled values. We intend to build up robust integrated spectral energy distribution of SSPs older than 1 Gyr by adopting the MILES database (Medium-resolution Isaac Newton Telescope Library of Empirical Spectra) and taking into account the Mg/Fe ratio of its stars. Magnesium is a proxy of the alpha-capture elements and the alpha/Fe ratio has been widely used as an indicator of the star formation time scale. In this talk, I present how accurate and extensive our compilation and determination of [Mg/Fe] were obtained around MILES to compute state-of-the-art SSP models. Published high resolution measurements were adopted to define a uniform scale of [Mg/Fe] and calibrate our results at medium resolution that were based on the spectral synthesis of two strong Mg features.
Abstract
The study of the Milky is expected to have a major impact on our understanding of how galaxies form and evolve. "Near-field cosmology" is being vigorously pursued through a series of major surveys of the Galaxy's stellar content (2-MASS, SDSS, RAVE, Hermes, Apogee, Gaia) that are either in hand or pending. It will be argued that what we want to know is deeply buried in these data and can only be extracted by comparing the surveys with a hierarchy of dynamical models of ever increasing complexity. Work currently being done to build such hierarchical models will be described, and some early results from this work will be summarised.
Abstract
El curso tendrá un carácter eminentemente práctico. Tras una breve serie de presentaciones sobre el proyecto Observatorio Virtual y las herramientas de análisis existentes se procederá al desarrollo de casos científicos reales utilizando una metodología VO. El desarrollo de estos casos científicos se realizará bajo la supervisión de personal del Observatorio Virtual Español.
Abstract
El curso tendrá un carácter eminentemente práctico. Tras una breve serie de presentaciones sobre el proyecto Observatorio Virtual y las herramientas de análisis existentes se procederá al desarrollo de casos científicos reales utilizando una metodología VO. El desarrollo de estos casos científicos se realizará bajo la supervisión de personal del Observatorio Virtual Español.
Abstract
El curso tendrá un carácter eminentemente práctico. Tras una breve serie de presentaciones sobre el proyecto Observatorio Virtual y las herramientas de análisis existentes se procederá al desarrollo de casos científicos reales utilizando una metodología VO. El desarrollo de estos casos científicos se realizará bajo la supervisión de personal del Observatorio Virtual Español.
Abstract
El curso tendrá un carácter eminentemente práctico. Tras una breve serie de presentaciones sobre el proyecto Observatorio Virtual y las herramientas de análisis existentes se procederá al desarrollo de casos científicos reales utilizando una metodología VO. El desarrollo de estos casos científicos se realizará bajo la supervisión de personal del Observatorio Virtual Español.
Abstract
El curso tendrá un carácter eminentemente práctico. Tras una breve serie de presentaciones sobre el proyecto Observatorio Virtual y las herramientas de análisis existentes se procederá al desarrollo de casos científicos reales utilizando una metodología VO. El desarrollo de estos casos científicos se realizará bajo la supervisión de personal del Observatorio Virtual Español.
Abstract
This talk is divided into two related parts. First, we will call your attention to a basic, but often overlooked worrying fact, and presents ways of dealing with it. The fact is: an enormous number of galaxies in surveys like the SDSS have emission lines which are too weak (low S/N) to be classified by usual schemes (ie, diagnostic diagrams). It turns out that most of these are AGN-like, so ignoring them on the basis of low S/N (which most people do) leaves as much as 2/3 of these emission line galaxies unaccounted for. The solution: We present a number of alternative methods to rescue this numerous population from the classification limbo. We find that about 1/3 of these weak-line galaxies are massive, metal rich star-forming systems, while the remaining 2/3 are more like LINERs. In the second part, we revisit the old idea by Binette et al (1994) that post-AGB stars can account for the emission line properties of some galaxies. A "retired galaxy" model is presented and compared to data in the SDSS. We find that about 1/4 of the galaxies classified as LINERs in the SDSS are consistent with this model, where all ionizing radiation is of stellar origin. More dramatically, nearly 100% of weak-line LINERs are perfectly consistent with being just retired galaxies, with no active nucleus. If these ideas are correct, contrary to current practice, relatively few LINERs should be counted as bona fide AGN.
Abstract
In this Breaking News seminar, I will describe our project dedicated to the search for ultracool low-metallicity dwarfs (or subdwarfs) in the large-scale databases. The highlight of the seminar is the discovery of a mid-L subdwarf, the fifth known to date, and the first one identified in the UKIRT Infrared Deep Sky Survey (UKIDSS). The spectroscopic nature of this subdwarf was confirmed with data obtained with GTC/OSIRIS in April 2009.Upcoming talks
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