Four years ago, we initiated a proper motion study of the Galaxy's central stellar cluster using diffraction-limited K[2.2 micron]-band images obtained with the W.M. Keck I 10-m telscope. With relative positional accuracies of 2 milliarcsec, we have been able to measure stars moving at velocities up to 1400 km s(-1) at projected distances from the apparent radio counterpart of the black hole, Sgr A(*) , down to 0.004 pc (0.1"). These measurements have not only provided us with direct dynamical evidence for a supermassive central black hole (Ghez et al. 1998), but have also permitted us to begin to constrain the orbits of these stars for the first time ever. We will present a detailed analysis of stars observed in the central 1"x1", including (1) constraints on the orbital parameters, (2) limits on the flux from Sgr A*, and (3) a discussion of S3, an intriguing variable source located a mere 70 milliarcsec away from the nominal position of Sgr A*. This work is supported by the NSF and the Packard Foundation.
American Astronomical Society Meeting Abstracts #194
- Pub Date:
- May 1999