Differences in carbon and nitrogen abundances between field and cluster early-type galaxies

The Astrophysical Journal (Impact Factor: 6.28). 05/2003; DOI: 10.1086/376825
Source: arXiv

ABSTRACT Central line-strength indices were measured in the blue spectral region for a sample of 98 early-type galaxies in different environments. For most indices (Mgb and in particular) ellipticals in rich clusters and in low-density regions follow the same index-sigma relations. However, striking spectral differences between field ellipticals and their counterparts in the central region of the Coma cluster are found for the first time, with galaxies in the denser environment showing significantly lower C4668 and CN2 absorption strengths. The most convincing interpretation of these results is a difference in abundance ratios, arising from a distinct star formation and chemical enrichment histories of galaxies in different environments. An scenario in which elliptical galaxies in clusters are fully assembled at earlier stages than their low-density counterparts is discussed. Comment: 12 pages, including 3 figures, accepted for publication in ApJL

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    ABSTRACT: I present a short summary of some of the results from my thesis. In this work we analyse a sample of 98 early-type galaxies situated in different environments. Using new models, that include a new and improved stellar library, we derive mean ages, metallicities and study the qualitative behaviour of different chemical elements. We conclude that more massive galaxies formed their stars on shorter time-scales than less massive ones. The formation epoch and time-scale of the star formation in the most massive galaxies is very similar in the field and in more dense environments, but the star formation is progressively more extended for less massive galaxies in less dense environments.

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