266 research outputs found
Studying the Stellar Populations of the Local Group with VLT
The power of high quality imaging combined with the large collecting area of
each VLT telescope is impressive, and there are clearly many exciting
discoveries waiting to be made. The study of resolved stellar populations will
certainly benefit greatly from this new observatory, as with Palomar before. We
will now be able to probe a much large range of star forming environment within
the Local Group, and specifically very low metallicity regions in nearby dwarf
irregular galaxies. The study of individual stars and star-formation regions in
the nearby universe is the only way we will understand the observations of
galaxy populations at high redshift. We present some initial results from the
BVI imaging of the Local Group galaxy Antlia made during FORS1 science
verification in January 1999.Comment: To appear in the proceedings of the VLT Opening Symposium, held in
Antofagasta, Chile in March 199
UVES Abundances of Stars in Nearby Galaxies: How Good are Theoretical Isochrones?
Here we report some results from an ESO-VLT programme to observe individual
stars in nearby dwarf galaxies at high resolution with the UVES spectrograph
(Tolstoy, Venn, Shetrone, Primas, Hill, Kaufer & Szeifert 2002, submitted to
AJ). We mainly concentrate on illustrating the issues and uncertainties
surrounding our efforts to determine the ages of stars for which we have
accurately measured [Fe/H] and [alpha/Fe].Comment: 2 page contribution to conference "New Horizons in Globular Cluster
Astronomy", Padua, June 2002 ed. G. Piotto, G. Meylan, G. Djorgovski, & M.
Riello, ASP Conf. Ser. (2002
The Optical Velocity of the Antlia Dwarf Galaxy
We present the results of a VLT observing program carried out in service mode
using FORS1 on ANTU in Long Slit mode to determine the optical velocities of
nearby low surface brightness galaxies. Outlying Local Group galaxies are of
paramount importance in placing constraints the dynamics and thus on both the
age and the total mass of the Local Group. Optical velocities are also
necessary to determine if the observations of HI gas in and around these
systems are the result of gas associated with these galaxies or a chance
superposition with high velocity HI clouds or the Magellanic Stream. The data
were of sufficient signal-to-noise to obtain a reliable result in one of the
galaxies we observed - Antlia - for which we have found an optical
helio-centric radial velocity of 351 15 km/s.Comment: 11 pages, 4 figures, 5 tables MNRAS, in pres
The chemical composition of Local Group dwarf spheroidals
I will review the progress of VLT spectroscopy of large numbers of individual
stars in nearby dwarf spheroidal galaxies. This spectroscopy has allowed us to
obtain detailed insights into the chemical and dynamical properties of the
resolved stellar population in these nearby systems.Comment: 8pages, 6 figures. Invited talk to appear in the proceedings of the
IAUC198 Coll. "Near-Field Cosmology with Dwarf Elliptical Galaxies", H.
Jerjen & B. Binggeli (eds.
The Local Group: Inventory and History
My presentation was an overview of what we know about the Local Group of
galaxies, primarily from optical imaging and spectroscopy. AGB stars are on the
whole a very sparse and unrepresentative stellar population in most Local Group
galaxies. However, more detailed studies of star formation histories and
chemical evolution properties of populations, like Main Sequence dwarf stars
and Red Giant Branch stars, allow a better understanding of the evolutionary
context in which AGB stars can be observed. There are a variety of galaxy types
in the Local Group which range from predominantly metal poor (e.g., Leo A) to
metal-rich (e.g., M 32). Dwarf galaxies are the most numerous type of galaxy in
the Local Group, and provide the opportunity to study a relatively simple,
typically metal-poor, environment that is likely similar to the conditions in
the early history of all galaxies. Hopefully the range of star formation
histories, peak star formation rates and metallicities will provide enough
information to properly calibrate observations of AGB stars in more distant
systems, and indeed in integrated spectra. Here I will summarise what we know
about the star formation histories of nearby galaxies and their chemical
evolution histories and then attempt to make a connection to their AGB star
properties.Comment: Invited Review, "Why Galaxies Care About AGB Stars II", eds. Franz
Kerschbaum, Thomas Lebzelter, and Bob Wing, Vienna, August 2010, 10 pages, 6
figure
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