Probing the Age of Elliptical Galaxies

Abstract

In this paper we address the question whether age and metallicity effects can be disentangled with the aid of the broad-band colours and spectral indices from absorption feature strengths, so that the age of elliptical galaxies can be inferred. The observational data under examination are the indices Hbeta and [MgFe], and the velocity dispersion Sigma for the sample of galaxies of Gonzales (1993), supplemented by the ultra-violet data, i.e. the colour (1550-V), of Burstein et al. (1988). The analysis is performed with the aid of chemo-spectro-photometric models of elliptical galaxies with infall of primordial gas (aimed at simulating the collapse phase of galaxy formation) and the occurrence of galactic winds. The galaxy models are from Tantalo et al. (1995).