Bibcode
Pierce, Michael; Bridges, Terry; Forbes, Duncan A.; Proctor, Robert; Beasley, M. A.; Gebhardt, Karl; Faifer, Favio Raul; Forte, Juan Carlos; Zepf, Stephen E.; Sharples, Ray; Hanes, David A.
Bibliographical reference
Monthly Notices of the Royal Astronomical Society, Volume 368, Issue 1, pp. 325-334.
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5
2006
Citations
35
Refereed citations
32
Description
NGC 4649 (M60) is one of a handful of giant Virgo ellipticals. We have
obtained Gemini/GMOS (Gemini North Multi-Object Spectrograph) spectra
for 38 globular clusters (GCs) associated with this galaxy. Applying the
multi-index χ2 minimization technique of Proctor and
Sansom with the single stellar population models of Thomas, Maraston and
Korn, we derive ages, metallicities and α-element abundance
ratios. We find several young (2-3 Gyr old) supersolar metallicity GCs,
while the majority are old (>10 Gyr), 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 α-element ratio with increasing metallicity is found.