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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
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Abstract

We present recent results from our long-term Gemini/GMOS study of globular clusters in early-type galaxies. To date, we have obtained photometry and spectroscopy for clusters in NGCs 3379, 4649, 524, 7332, and IC 1459. We find a clear bimodality in the NGC 4649 cluster colour distribution, with the fraction of blue/red clusters increasing with galactocentric radius. We derive ages and metallicities for 22 clusters 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 cluster 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 globular cluster data.

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Terry Bridges, Mike Beasley, Favio Faifer, Duncan Forbes, Juan Forte, Karl Gebhardt, Dave Hanes, Ray Sharples, Steve Zepf. 2003-10-13. Globular Clusters in Early-Type Galaxies with GMOS. https://arxiv.org/abs/astro-ph/0310324

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