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Extragalactic globular clusters: unraveling galaxy formation and constraining stellar evolution theories

Published online by Cambridge University Press:  01 December 2006

A. Javier Cenarro ,
Michael A. Beasley ,
Jay Strader ,
Jean P. Brodie  and
Duncan A. Forbes
A. Javier Cenarro
Affiliation:
Instituto de Astrofísica de Canarias, Vía Láctea s/n, E-38200 La Laguna, Tenerife, Spain email: cenarro@iac.es Dpto. de Física de la Tierra, Astronomía y Astrofísica II, Fac. de Ciencias Físicas, Universidad Complutense de Madrid, 28040 Madrid, Spain Lick Observatory, University of California, CA 95064, USA
Michael A. Beasley
Affiliation:
Instituto de Astrofísica de Canarias, Vía Láctea s/n, E-38200 La Laguna, Tenerife, Spain email: cenarro@iac.es Lick Observatory, University of California, CA 95064, USA
Jay Strader
Affiliation:
Lick Observatory, University of California, CA 95064, USA
Jean P. Brodie
Affiliation:
Lick Observatory, University of California, CA 95064, USA
Duncan A. Forbes
Affiliation:
Centre for Astrophysics & Supercomputing, Swinburne U., Hawthorn VIC 3122, Australia
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Abstract

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Understanding the stellar populations of extragalactic globular cluster (GC) systems and, in particular, determining their ages, provide essential clues to constrain the star formation histories of their host galaxies. We here summarize the most relevant results derived from a detailed, spectroscopic study of 20 GCs in the E0 NGC 1407. We find most GCs are old (~11 Gyr), follow a tight metallicity sequence reaching values slightly above solar, and exhibit mean [α/Fe] ratios of ~0.3 dex. Blue horizontal branch effects are detected for 3 GCs. We also report the existence of two families of metal-rich (MR) GCs, as some of them exhibit significantly larger [Mg/Fe] and [C/Fe] ratios, what might be interpreted in terms of different star formation time-scales. Striking CN overabundances are found over the entire GC metallicity range. In particular, for MR GCs, N increases dramatically while C essentially saturates. This may be interpreted as a consequence of the increasing importance of the CNO cycle with increasing metallicity.

Keywords

globular clusters: general — galaxies: clusters — galaxies: formation
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 2 , Symposium S241: Stellar Populations as Building Blocks of Galaxies , December 2006 , pp. 445 - 448
Copyright
Copyright © International Astronomical Union 2007

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