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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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Bulletin of the American Astronomical Society, 36 5
© 2004. The American Astronomical Society.