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Session 41 - Elliptical Galaxies.
Display session, Tuesday, January 14
Metropolitan Ballroom,

[41.01] Synthetic Spectra of Elliptical Galaxies

M. L. Houdashelt, R. A. Bell (U. Maryland), A. V. Sweigart (NASA GSFC)

We present our most recent population synthesis models of elliptical galaxies. Each elliptical galaxy is modelled as a simple stellar population, i.e. a group of stars having a common age and metallicity. The effective temperature, surface gravity distribution of the stars in each galaxy can thus be represented by a single isochrone, to which we add horizontal-branch and asymptotic-giant-branch sequences. Using updated MARCS stellar atmosphere models, we have calculated synthetic stellar spectra with the SSG spectral synthesis code for a representative sample of stars along isochrones of various ages and metallicities. Assuming a Salpeter initial mass function, we have determined luminosity functions (LFs) for each of these isochrones and used these LFs to construct integrated synthetic spectra of elliptical galaxies. Here, we explore the effects of changes in the age and metallicity of the stellar population on the optical and near-infrared (0.3--3 \mum) regions of the spectral energy distribution. We begin by measuring broad-band colors and the strengths of various molecular bands and atomic lines, including the Lick indices, from the synthetic integrated spectra. We then examine the variations in these parameters with the age and metallicity of the stellar population and compare their behavior to the predictions of other published models and to the trends observed in early-type galaxies.

Program listing for Tuesday