In Stellar Astrophysics with the World's Largest Telescopes, AIP Conference Proceedings, Vol. 752, eds. J. Mikolaewska & A. Olech (New York: American Institute of Physics), p.161-174, 2005.
astro-ph/0508147

For a PDF version of the article, click here.

STELLAR POPULATIONS IN THE LOCAL GROUP OF GALAXIES

Eva K. Grebel


Astronomical Institute of the University of Basel, Venusstrasse 7, CH-4102 Binningen, Switzerland


Abstract. The characteristics and properties of the stellar populations and evolutionary histories of Local Group galaxies are summarized and compared to predictions of cosmological models. No clear signature of the re-ionization epoch is observed; in particular, there is no cessation of star formation activity in low-mass dwarf galaxies at the end of re-ionization. Arguments against the morphological transformation of dwarf irregular into dwarf spheroidal galaxies are derived from their pronounced evolutionary differences at early epochs as evidenced by the offset in the metallicity-luminosity relation between gas-rich and gas-poor dwarfs. While there is increasing evidence for past and ongoing accretion events the overall importance of dwarf galaxies as building blocks remains unclear considering their differences in modes of star formation and detailed chemistry.


Keywords Dwarf galaxies (elliptical, irregular, and spheroidal) - Magellanic Clouds and other irregular galaxies - Origin, formation, evolution, age, and star formation - Chemical composition and chemical evolution - Stellar content and populations; radii; morphology and overall structure - Galactic halos.


Table of Contents

THE LOCAL GROUP
The galaxy content of the Local Group
Galaxy types in the Local Group
Morphological segregation
Direct evidence for harassment and accretion

THE EARLIEST EPOCH OF STAR FORMATION

STAR FORMATION HISTORIES AND METALLICITIES
Mean metallicities and the metallicity-luminosity relation
Detailed abundance ratios

REFERENCES

Next