paper

Gemini/GMOS Spectra of Globular Clusters in the Virgo Giant Elliptical NGC 4649

arXiv:astro-ph/0601531 · doi:10.1111/j.1365-2966.2006.10097.x

Abstract

NGC 4649 (M60) is one of a handful of giant Virgo ellipticals. We have obtained Gemini/GMOS spectra for 38 GCs associated with this galaxy. Applying the multi-index chi^2 minimisation technique of Proctor & Sansom (2002) with the single stellar population models of Thomas, Maraston & Korn (2004) we derive ages, metallicities and alpha-element abundance ratios. We find several young (2--3 Gyr old) super-solar metallicity GCs, while the majority are old (>10 Gyrs), spanning a range of metallicities from solar to [Z/H]=-2. At least two of these young GCs are at large projected radii of 17-20 kpc. The galaxy itself shows no obvious signs of a recent starburst, interaction or merger. A trend of decreasing alpha-element ratio with increasing metallicity is found.

12 pages, 4 figs, 6 tables, MNRAS accepted

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