SIMBAD references

We have obtained two-dimensional spectral data for a sample of 58 nearby S0 galaxies with the Multi-Pupil Fiber/Field Spectrograph of the 6 m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences. The Lick indices Hβ, Mg b, and <Fe> are calculated separately for the nuclei and for the bulges taken as the rings between R=4'' and 7", and the luminosity-weighted ages, metallicities, and Mg/Fe ratios of the stellar populations are estimated by comparing the data to single stellar population (SSP) models. Four types of galaxy environments are considered: clusters, centers of groups, other places in groups, and the field. The nuclei are found to be on average slightly younger than the bulges in any type of environment, and the bulges of S0 galaxies in sparse environments are younger than those in 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 environments are on average less massive than those in dense environments), but for the most massive S0 galaxies, with σ_*=170-220 km/s, the age dependence on the environment is still significant at the confidence level of 1.5 σ.