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P. Barmby (CfA)
Globular cluster ages are more than just lower limits on the age of the universe; the distribution of ages constrains the timescale for galaxy formation and chemical evolution. The Milky Way has long been known to have two distinct populations of clusters, with different metallicities and kinematics, and multiple globular cluster populations have now been detected in many galaxies. I use color and luminosity distributions to examine the relative ages of the two cluster populations in M31, and find that the metal-rich clusters could be up to 50% younger than the metal-poor clusters. While a small delay in the formation of metal-rich clusters might be imposed by chemical enrichment timescales, a large age gap demands a more detailed explanation. I outline several possibilites and the promises and problems of each.
This work was supported by the Smithsonian Institution.