Carretero, C.Vazdekis, A.Beckman, J. E.Sánchez Blázquez, PatriciaGorgas García, Francisco Javier2023-06-202023-06-202004-07-100004-637X10.1086/422749https://hdl.handle.net/20.500.14352/51838© 2004. The American Astronomical Society. All rights reserved. The authors thank A. Aguerri, X. Barcons, L. Carigi, C. Gutiérrez, R. Peletier, and the anonymous referee for useful comments. We acknowledge grant AYA2001-0435 from the Spanish Ministry of Science and Technology. The SDSS is managed by the ARC for the Participating Institutions.We present estimates of CN and Mg overabundances with respect to Fe for early-type galaxies in eight clusters over a range of richness and morphology. Spectra were taken from the Sloan Digital Sky Survey Data Release 1 and from William Hershel Telescope and Centro Astronómico Hispano-Alemán observations. Abundances were derived from absorption lines and single-burst population models, by comparing galaxy spectra with appropriately broadened synthetic model spectra. We detect correlations between the [Mg/CN] and [CN/Fe] values and the cluster X-ray luminosity. No correlation is observed for [Mg/Fe]. We also see a clear trend in the richness and morphology of the clusters. This is interpreted as giving varying formation timescales for CN, Mg, and Fe and a varying star formation history in early-type galaxies as a function of their environment: intermediate-mass early-type galaxies in more massive clusters are assembled on shorter timescales than in less massive clusters, with an upper limit of ~1 Gyr.engjournal articlehttp://dx.doi.org/10.1086/422749http://iopscience.iop.org/open access52Color-magnitude diagramDigital sky surveyPopulation synthesisElliptic galaxiesDistant clustersFeature indexesEvolutionSampleStarsAbundancesAstrofísicaAstronomía (Física)