SIMBAD references

Central and mean metallicities are calculated for a sample of 40 early-type galaxies, whose color gradients were reported in a previous paper (Idiart et al., 2002A&A...383...30I). The present color-metallicity calibration was derived from a grid of evolutionary models which fit the color-magnitude sequence of ellipticals in Coma and Virgo clusters. The mean metallicity gradient derived from our data is (Δ[Fe/H]/Δlogr)=-0.26±0.08 and the mean sample average metallicity is <[Fe/H]≥0.01±0.11 (rmsd). Central and mean metallicities are correlated with the central velocity dispersion, consistent with the interpretation by metallicity variations of the color-magnitude sequence and of color gradients. Age effects are also discussed, in particular concerning the interpretation of the Hβ line strength in those objects.