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2017 Hot Sci @ STScI

HST Proper Motions of Distant Globular Clusters: Constraining the Formation & Mass of the Milky Way

Presented by: Tony Sohn  (Space Telescope Science Institute)
Category: Science Colloquia   Duration: 30 minutes   Broadcast date: August 09, 2017
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The globular cluster (GC) system of the Milky Way (MW) provides important information on the MW’s present structure and past evolution. GCs in the halo are particularly useful tracers; because of their long dynamical timescales, their orbits retain imprints of their origin or accretion history. Full 3D motions are required to calculate past orbits, but accurate proper motion (PM) measurements are available for only a few halo GCs. We have created the first high-quality HST PM database for halo GCs located out to R_GC~100 kpc, based on our technique to determine absolute PMs using distant background galaxies as stationary reference sources. I will present preliminary results from this project, and report progress on our work to increase understanding of the formation, evolution, and mass of the MW using our results. I will also describe how PM measurements with HST continues to be advantageous in the Gaia era.