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OATS-DAUT SEMINAR
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Speaker:
Giuseppina Battaglia (ESO, Garching, D)
Title:
Chemistry and kinematics of stars in Milky Way dwarf spheroidal
galaxies
Date: Tuesday, November 25th, 2008
Time: 12:00
Venue: Villa Bazzoni
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Abstract:
Dwarf spheroidal galaxies (dSphs) are faint,
small systems, which can be studied in great detail, on a star-by-star
basis, in the vicinity of the Milky Way. The relevance of these
objects is manifold, both from a cosmological and galaxy
formation/evolution point of view. dSphs appear to be the smallest
systems requiring presence of dark matter, and may even be the most
dark matter dominated ones. This makes them good testing grounds for
predictions of different dark matter models. Their simplicity with
respect to larger galaxies offers a great opportunity to learn about
the physical processes around star formation and chemical
enrichment. Furthermore, current theories of hierarchical structure
formation predict that small galaxies are the building blocks of
larger ones. Therefore a detailed study of individual stars in these
nearby systems is an important step to understand and model the
contribution of small galaxies to the assembly of larger galaxies.
As part of the DART project we have carried out detailed studies of a
sample of Milky Way dSphs in order to improve our understanding of the
properties of these small stellar systems. We have used the ESO/2.2m
Wide Field Imager to obtain large area photometry and FLAMES at the
VLT to obtain intermediate resolution spectra in the CaII triplet
region for hundreds of individual stars out to the nominal tidal radii
of these objects.
In this talk I will give an overview of the DART photometric and
spectroscopic survey of the Sculptor and Fornax dSphs. I will show
that the metallicity and kinematic properties of these systems are
quite complex, with the presence of multiple stellar populations, and
in Sculptor even of statistically significant rotation. I will then
focus on results from the kinematic modelling of Sculptor, aimed to
derive the mass content of this object and test predictions from dark
matter models. I will show that modelling of the different kinematics
and spatial distribution of the multiple stellar populations allows a
more accurate determination of the mass of Sculptor with respect to
other methods commonly used.
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contact: Andrea Biviano (OATS)