Effect of Environment on the Underlying Stellar Populations of Dwarf Elliptical Galaxies in the Coma Cluster

We derive ages, metallicities and [α/Fe] ratios for dwarf early‐type galaxies (dE/dS0) in the center and a region believed to be infalling into the Coma cluster. We find that a set of metallic indices cannot be described by linear relations with velocity dispersion (σ), while another group of indices exhibits linear index‐σ relations. dE/dS0 galaxies in the core of the cluster are on average younger, and have lower metallicities and lower α‐ratios (solar to sub‐solar) than the more luminous elliptical galaxies. On the other hand, dEs/dS0s in the infall region of Coma form a less homogeneous population. We find an unusually high fraction of dE/dS0s with high [α/Fe] ratios, suggesting short time scales for the star formation histories for these galaxies. Furthermore, the dE/dS0s with high α‐ratios have a range of ages and metallicities implying multiple formation scenarios where some galaxies have experienced their short star formation bursts at more recent epochs.