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Publication details for Prof Ray Sharples

Beasley, M. A., Sharples, R. M., Bridges, T. J., Hanes, D. A., Zepf, S. E., Ashman, K. M. & Geisler, D. (2002), Ages and Metallicities of Globular Clusters in NGC 4472, in Geisler, D. P., Grebel, E. K. & Minniti, D. eds, Proceedings of the symposium of the IAU, 207 207: Extragalactic Star Clusters, 207th IAU Symposium 207. Pucón, Chile, Astronomical Society of the Pacific, San Francisco, 318.

Author(s) from Durham


We have derived ages and metallicities from co-added spectra of 131 globular clusters (GCs) associated with the giant Virgo elliptical NGC 4472. From their metal-line indices, we find that our sample of GCs span a metallicity range of approximately -1.6 <= [Fe/H] <= 0 dex. The SSP models of Worthey (1994; W94) predict that the metal-poor population of GCs has an age of 14.5 ± 4 Gyr and that the metal-rich population is 13.8 ± 6 Gyr old, whilst the models of Kurth, Fritze-v. Alvensleben & Fricke (1999; KFF99) predict ages of 6.0 ± 2 and 8.0 ± 5 respectively. We conclude that, within the uncertainties, the GCs are old and coeval, and that the bimodality seen in the broadband colours primarily reflects metallicity and not age differences.