Invited review to appear in the proceedings of "Microlensing 2000: A New Era of Microlensing Astrophysics", Cape Town, South Africa, ASP Conf. Ser., eds. J.W. Menzies and P.D. Sackett


THE LOCAL GROUP

Eva K. Grebel


University of Washington, Department of Astronomy, Box 351580, Seattle, WA 98195-1580, USA
Hubble Fellow
Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg, Germany


Abstract. Local Group galaxies such as the Milky Way, the Magellanic Clouds and M31 are being used by a number of international collaborations to search for microlensing events. Type and number of detections place constraints on dark matter and the stellar populations within and along the line of sight to these galaxies. In this review I briefly discuss the stellar populations, evolutionary histories, and other properties of different types of Local Group galaxies as well as constraints on the dark matter content of these galaxies. Particular emphasis is placed on the dwarf companions of the spiral galaxies in the Local Group.


Table of Contents

INTRODUCTION

LOCAL GROUP GALAXY CONTENT AND DISTRIBUTION

THE LOCAL GROUP SPIRALS

STAR FORMATION HISTORIES OF LOCAL GROUP DWARF GALAXIES
Methods and Limitations
Old Populations
Spatial Variations of Stellar Populations
Differences in Gas Content
Star Formation Histories
Potential Evolutionary Transitions

DARK MATTER
Dwarf Spheroidal Galaxies and Dark Matter
Tidal Effects Rather than Dark Matter?
Modified Newtonian Dynamics
Implications for Microlensing

SUMMARY

REFERENCES

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