Globular Clusters in Early-Type Galaxies with GMOS

TERRY BRIDGES; MIKE BEASLEY; FAVIO FAIFER; DUNCAN FORBES; JUAN FORTE; KARL GEBHARDT; DAVE HANES; RAY SHARPLES; STEVE ZEPF

Sydney, Australia

Congreso; Extragalactic Globular Clusters and their Host Galaxies, 25th meeting of the IAU.; 2003

IAU

We present recent results from our long-term Gemini/GMOS study of globular clusters (GCs) in early-type galaxies. To date, we have obtained photometry and spectroscopy for GCs in NGCs 3379, 4649, 524, 7332, and IC 1459. We find a clear bimodality in the NGC 4649 GC colour distribution, with the fraction of blue/red clusters increasing with galactocentric radius. We derive ages and metallicities for 22 GCs in NGC 3379, finding that most of the clusters appear old (10 15 Gyr); however, there is a group of 4 metal-rich, younger clusters with ages of 2 6 Gyr. The NGC 3379 GC velocity dispersion decreases with radius, as does the inferred (local) mass-to-light ratio: there is no evidence for a dark matter halo in NGC 3379 based on our GC data.