Open AccessGemini/GMOS spectra of globular clusters in the Virgo giant elliptical NGC 4649
Author(s) -
Pierce Michael,
Bridges Terry,
Forbes Duncan A.,
Proctor Robert,
Beasley Michael A.,
Gebhardt Karl,
Faifer Favio Raul,
Forte Juan Carlos,
Zepf Stephen E.,
Sharples Ray,
Hanes David A.
Publication year - 2006
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2006.10097.x
Subject(s) - physics , globular cluster , astrophysics , metallicity , virgo cluster , galaxy , red giant branch , stellar population , astronomy , elliptical galaxy , spectrograph , spectral line , star formation
ABSTRACT 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 χ 2 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.