The W. M. Keck Dynamical Study of the Galaxy's Central Stellar Cluster

A. M. Ghez

1 Dept of Physics and Astronomy, UCLA, Los Angeles, CA 90095-1562

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The advent of Adaptive Optics as brought a new powerful tool to near-infrared studies of the Galactic Center. This presentation will focus on the ways in which the new AO results have furthered the W. M. Keck Observatory dynamical study of the Galaxy's central stellar cluster. In particular, it has doubled the number of stars included in the seven year base-line proper motion sample, identified stars moving with velocities up to 3,000 km/sec (twice as fast as that previously reported), and allowed spectroscopic measurements of a subset of stars. With significant curvature measured, a full orbital analysis is now possible. This has increased the inferred dark mass density by three orders of magnitude compared to previous experiments, and thereby dramatically strengthened the case for the presence of a super-massive black hole.