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.
|Jeudi, le 28 mars 2013