AAS 204th Meeting, June 2004
Session 40 Galaxies
Poster, Tuesday, June 1, 2004, 10:00am-7:00pm, Ballroom

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[40.07] Spectral Indices of Elliptical Galaxies as a Function of Alpha Element Abundance Ratios

M. L. Houdashelt (Johns Hopkins University)

We have expanded and updated our grid of synthetic stellar spectra of low-mass stars and, using published isochrones, constructed evolutionary synthesis models of early-type galaxies. Our new stellar grid includes stars with metallicities spanning the range from old, Milky Way globular clusters to massive elliptical galaxies and also includes models having both solar abundance ratios and enhanced [alpha/Fe] ratios. For both the grid and the integrated-light models, we have measured the Lick indices, as well as the strengths of the Ca II triplet, the 2.3 micron CO bands, and a variety of other atomic and molecular features in the optical and near-infrared. In this poster, we describe the behavior of these integrated spectral features as functions of [Fe/H], age, and [alpha/Fe], and we discuss some of the implications for the formation and evolution of elliptical galaxies.

This work is funded by NASA Grant NAG5-10922.

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