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

Michael Pierce; Terry Bridges; Duncan A. Forbes; Robert Proctor; Michael A. Beasley; Karl Gebhardt; Favio Raul Faifer; Juan Carlos Forte; Stephen E. Zepf; Ray Sharples; David A. Hanes

doi:10.1111/j.1365-2966.2006.10097.x

arXiv · astro-ph/0601531

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

Michael Pierce·Terry Bridges·Duncan A. Forbes·Robert Proctor·Michael A. Beasley·Karl Gebhardt·Favio Raul Faifer·Juan Carlos Forte·Stephen E. Zepf·Ray Sharples·David A. Hanes

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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.

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Michael Pierce, Terry Bridges, Duncan A. Forbes, Robert Proctor, Michael A. Beasley, Karl Gebhardt, Favio Raul Faifer, Juan Carlos Forte, Stephen E. Zepf, Ray Sharples, David A. Hanes. 2006-01-24. Gemini/GMOS Spectra of Globular Clusters in the Virgo Giant Elliptical NGC 4649. https://doi.org/10.1111/j.1365-2966.2006.10097.x

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