AAS 204th Meeting, June 2004
Session 80 Nearby Galaxies
Poster, Thursday, June 3, 2004, 9:20am-4:00pm, Ballroom

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[80.05] The Pace of Star Formation in Local Group Dwarf Galaxies

J. S. Gallagher (University of Wisconsin-Madison), E. K. Grebel (Unversity of Basel), D. Harbeck (University of Wisconsin-Madison)

Cold dark matter models predict that low mass galaxies will form first and that some of these objects will survive to be seen as present day dwarf galaxies. Most theoretical models further suggest that star formation in low mass dwarfs will be truncated by reionization, so that the least massive dwarfs universally will make most of their stars within the first Gyr after the big bang. In comparing these expectations with the observed star formation histories of nearby dwarf galaxies, we find that most dwarfs followed more complex evolutionary paths, including star formation extending over many Gyr even in the `stellar fossil' dSphs . Furthermore evolutionary histories correlate with location in the Local Group. We suggest that local conditions have been more important than global reionization in shaping the early destinies of nearby dwarf galaxies. We thank the NSF grant AST9803018, the Graduate School, University of Wisconsin, and McKinney Foundation for support of this research.


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