Kinematics of Stellar Systems: Distances, Mass Distributions, and Binary Star Frequencies

'Kinematics of Stellar Systems: Distances, Mass Distributions and Binary Star Frequencies'

AST-0098650

This project investigates the structure, stellar content and dynamical evolution of globular clusters and of the dark matter content of the dwarf spheroidal companion galaxies of our own Milky Way. Advantage is taken of the enormous amount of data that can be obtained with the Rutgers Fabry-Perot imager. This instrument is one of the few that can acquire the wide-field radial velocity data which are required to address these challenges. Combining Fabry-Perot measurements of the radial velocity distribution with HST determinations of the distribution of proper motions for member stars will yield direct geometrically based measures of the distances to 13 globular clusters. These new distances will have uncertainties about one-fifth as large as the currently accepted values. Repeated velocity measurements are one of the most productive ways of discovering binary stars and the greatly increased numbers which are expected will test models for the dynamical evolution of globular cluster binaries. The project will use three-color stellar photometry with the wide-field imagers to search for tidal tails of stellar debris associated with the Draco dwarf spheroidal galaxy. Radial velocity measurements of the stars thus found can yield total dark matter masses for the dwarf spheroidal galaxy and the rate at which stars are being lost from the system. Thus, the work done under this award will impact upon several areas of astrophysics including the extragalactic distance scale and the characteristics of dark matter in dwarf spheroidal galaxies.