Synthetic Spectra of M Giants

Abstract


The importance of M stars in the integrated light of early-type galaxies is evident from the TiO bands seen in the spectra of these galaxies. Recent models of the Galactic bulge, which has been shown to have an integrated spectrum similar to that of an "average" elliptical galaxy, indicate that the M giants there contribute approximately 10% of the V-band flux and greater than half of the light in the K band (Houdashelt 1995). We present here some preliminary synthetic spectra of M giants for use in the population synthesis of galaxies. Using the MARCS model atmosphere program and SSG spectral synthesis code, we have constructed a grid of synthetic spectra of early-M (M0-M5) giants which span wavelengths from the optical (3000 A) to the near-infrared (5 um). These spectra have been tested through a direct comparison to observed spectra of nearby field stars. A special emphasis has been placed upon modelling the TiO bands. Colors have been derived from the synthetic spectra and MK spectral types have been estimated using the eight-color system of Wing. Comparisons are made to the trends seen in the colors and spectral types of field M giants.
Back to Mark Houdashelt's Home Page