The HST/ACS Galactic Globular Cluster Treasury Program

Brian Chaboyer

Dartmouth College

The HST/ACS Galactic Globular Cluster Treasury Program has obtained deep images of 65 Galactic globular clusters. Globular clusters (GCs) are powerful tracers of the Galactic halo, thick disk, and bulge populations. The ages, metallicities, and kinematics of the GCs bear the imprint of the Galaxy's early formation history. Cluster whose stars share the same age and chemical composition and only differ in mass play an important role in studies of stellar structure and evolution and in the formation and evolution of the Galaxy. Combined,the Galactic GCs have the potential to answer questions in a broad range of fields from star formation and evolution to galaxy formation and evolution. I will present an overview of the initial results of the Treasury program. These include an examination of the multiple stellar populations in the glublar cluster M54, which is at the center of the Sagattarius dwarf galaxy, the discovery of two separate stellar populations in the globular cluster NGC 1851 and new results on the relative ages of these 65 clusters.

Date:	Thursday, 22 October 2009
Time:	11:30
Where:	Université de Montréal
	Pavillon Roger-Gaudry, Local D-460
Contact:	Pierre Bergeron