Stellar Populations in Nearby Lenticular Galaxies

Abstract

We have obtained 2D spectral data for a sample of 58 nearby S0 galaxies with the Multi-Pupil Spectrograph of the 6m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences. The Lick indices H-beta, Mgb, and <Fe> are calculated separately for the nuclei and for the bulges taken as the rings between R=4&#34; and 7&#34;; and the luminosity-weighted ages, metallicities, and Mg/Fe ratios of the stellar populations are estimated by confronting the data to SSP models. Four types of galaxy environments are considered: clusters, centers of groups, other places in groups, and field. The nuclei are found to be on average slightly younger than the bulges in any types of environments, and the bulges of S0s in the sparse environments are younger than those in the dense environments. The effect can be partly attributed to the well-known age correlation with the stellar velocity dispersion in early-type galaxies (in our sample the galaxies in sparse environements are on average less massive than those in dense environments). However for the most massive S0s, with the stellar velocity dispersion of 170-220 km/s, the age dependence on the environment is still significant at the confidence level of 1.5 sigma.