Cenarro, A. J.Sánchez Blázquez, PatriciaCardiel López, NicolásGorgas García, Francisco Javier2023-06-202023-06-202004-10-200004-637X10.1086/425862https://hdl.handle.net/20.500.14352/51334© 2004. The American Astronomical Society. All rights reserved. The authors are indebted to the referee, S. M. Faber, for useful comments and suggestions. A. J. C. acknowledges financial support from a Universidad Complutense de Madrid Fundación del Amo Fellowship. The William Herschel Telescope is operated on the island of La Palma by the Royal Greenwich Observatory at the Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias. This work was supported by the Spanish research project AYA2003-01840.We present measurements of the Ca II 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 elliptical galaxies in the field, Coma galaxies with velocity dispersions in the range approximate to180-270 km s(-1) 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 Ca II triplet of galaxies are not able by themselves to simultaneously reconcile the strengths of the two Ca indices in both environments.engjournal articlehttp://dx.doi.org/10.1086/425862http://iopscience.iop.org/open access52Infrared caII tripletStellar population synthesisColor-magnitude relationElliptic galaxiesEmpirical calibrationGlobular-clustersII tripletAbsorptionAbundancesSpheroidsAstrofísicaAstronomía (Física)Física atmosférica2501 Ciencias de la Atmósfera