Stellar populations of cluster E and S0 galaxies

Spectral line indices for a sample of 290 nearby E and S0 galaxies are usedto investigate the stellar populations of these galaxies. Relations areestablished between the line indices (Mg2, , Hbeta) and the velocitydispersions, the masses of the galaxies, the M/L ratios and the clusterenvironment. The difference between the slope of the Mg2-sigma relation and theslope of the -sigma relation indicates that the abundance ratio [Mg/Fe]increases with the velocity dispersion. The index is stronger correlatedwith the projected cluster surface density, than with the galaxy mass or thevelocity dispersion. Also the Mg2 index depends on the cluster environment. Thedependence on the environment implies that [Mg/Fe] decreases with increasingdensity. The M/L ratios are strongly correlated with the Mg2 and Hbeta, while is only weakly correlated with the M/L ratio. Based on current stellar population models it is not yet possible to deriveunique physical parameters (mean age, mean abundances, mean IMF, and fractionof dark matter) from the observables (line indices, velocity dispersion, mass,M/L ratio).Comment: 29 pages, 14 figures and 10 tables included, LaTeX MN style. Accepted for publication in MNRA