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

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Matkovic, A.
Guzmán, R.
Sánchez Blázquez, P.
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American Institute of Physics
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We derive ages, metallicities and [alpha/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 (sigma), while another group of indices exhibits linear index-sigma relations. dE/dS0 galaxies in the core of the cluster are on average younger, and have lower metallicities and lower alpha-ratios (solar to sub-solar) than the more luminous elliptical galaxies. On the other hand, dEs/dSos in the infall region of Coma form a less homogeneous population. We find an unusually high fraction of dE/dS0s with high [alpha/Fe] ratios, suggesting short time scales for the star formation histories for these galaxies. Furthermore, the dE/dS0s with high alpha-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.
© 2009 American Institute of Phiysics. International Conference on Probing Stellar Populations out to the Distant Universe (2008. Cefalu, Italy). I thank the SOC for financial support to attend the conference.
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