Metallicity indices for multipopulation models .1. The galactic bulge

We report new spectroscopic observations on integrated light from the galactic bulge in Baade's window in the range 4700-6000 Angstrom. Metallicity indices H beta, Mg-2, Mgb, Fe5270, Fe5335, and Na D were measured. Foreground disk stars may certainly affect the hydrogen index, but their contribution to the magnesium and iron indices is probably small. The velocity dispersion derived from the Fourier quotient method is 112+/-14 km/s, in very good agreement with kinematical data from bulge K giants, giving further support to the interpretation that the integrated light is dominated by those stars. Multipopulation models synthesizing the observed iron and magnesium indices indicate a mean metallicity [Fe/H]=-0.02, a mean abundance ratio [Mg/Fe]=+0.45, and a mean age of 14.0+/-1.2 Gyr for the bulk of the bulge stars. The derived metallicity and abundance of ''alpha elements'' (here represented by magnesium) are consistent with existing low-resolution spectra and photometric data. (C) 1996 American Astronomical Society.