Early-Type Galaxies in the Coma Cluster: A New Piece in the Calcium Puzzle

Authors :: Nicolás Cardiel
Javier Gorgas
A. J. Cenarro
Patricia Sanchez-Blazquez
Source :: E-Prints Complutense. Archivo Institucional de la UCM, instname, E-Prints Complutense: Archivo Institucional de la UCM, Universidad Complutense de Madrid
Publication Year :: 2004
Publisher :: American Astronomical Society, 2004.
Abstract: We present measurements of the CaII triplet and the Ca4227 Lick-index for a sample of early-type galaxies in the Coma cluster, deriving, for the first time, their corresponding relationships with velocity dispersion. Compared with a similar subsample of ellipticals in the field, Coma galaxies with velocity dispersions in the range ~ 180-270 km/s exhibit significant differences in the strengths of the Ca features, suggesting an influence of the environment on the star formation histories of these galaxies. We argue that the main scenarios previously proposed to explain the relatively low CaII triplet of galaxies are not able by themselves to simultaneously reconcile the strengths of the two Ca indices in both environments.<br />6 pages including 2 figures. Accepted for publication in ApJL. For associated data tables see http://www.ucm.es/info/Astrof/ellipt/CATRIPLET.html