HST Observations of Globular Clusters and Metal-Poor Stars

Dr. Brian Chaboyer

Department of Physics and Astronomy Dartmouth University

Results from two large HST programs on globular clusters and metal-poor stars will be discussed. The ACS Survey of Galactic Globular Clusters obtained deep, uniform photometry of the central 3 arcminutes of 65 galactic globular clusters. I will highlight some important results from this survey, including the discovery of multiple stellar populations in some globular clusters, constraints on the three-dimensional orientation of the Sagittarius dwarf galaxy and the relative ages of the 65 clusters. Initial results from an on-going HST program which uses the fine guidance sensors to obtain accurate parallaxes of metal-poor ([Fe/H] < -1.5) main sequence field stars will also be presented. These stars are used to test stellar evolution models and as standard candles to determine distances to metal-poor globular clusters.

Date:	Thursday, 28 March 2013
Time:	16:00
Where:	Bishop's University
	Hamilton 303
Contact:	Lorne Nelson