AAS 205th Meeting, 9-13 January 2005
Session 93 Dwarf Galaxies
Poster, Wednesday, January 12, 2005, 9:20am-6:30pm, Exhibit Hall

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[93.11] Paleochemistry of Local Group Dwarf Irregular Galaxies

A.A. Cole, E. Tolstoy (Kapteyn Inst.), M. Irwin (Cambridge), T. Szeifert (ESO), K. Venn (Macalester Coll.)

We have begun a program to measure the metallicity distribution functions of the intermediate-age and old stellar populations in a sample of Local Group dwarf irregular galaxies. Existing data on the nebular abundances in HII regions and the stellar abundances in bright supergiants provide detailed information on the present-day chemistry of dwarf galaxies; our data provide a temporal dimension to this study.

Using the FORS2 spectrograph at ESO's Very Large Telescope, we have obtained medium-resolution spectra in the near-infrared calcium II triplet region for dozens of individual red giants in each of four galaxies: IC 1613, NGC 6822, WLM, and Phoenix. These data will provide strong new constraints on the evolutionary histories of small, isolated galaxies, shed light on the development of the mass-metallicity relation, and elucidate spatial and temporal patterns of chemical evolution within galaxies.

AAC is supported by a fellowship from The Netherlands Research School for Astronomy (NOVA).

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© 2004. The American Astronomical Society.