AAS 201st Meeting, January, 2003
Session 68. Structure of Galaxies with Central Masses
Oral, Tuesday, January 7, 2003, 2:00-3:30pm, 602-604

[Previous] | [Session 68] | [Next]

[68.04] Full 3-D Orbital Solutions for Stars Making a Close Approach to the Supermassive Black Hole at the Center of the Galaxy

A. M Ghez, G. Duchene, M. Morris, E. E. Becklin, S. D. Hornstein, A. Tanner, Ted Kremenek (UCLA), K. Matthews, D. Thompson, B. T. Soifer (Caltech), J. Larkin, I. McLean (UCLA)

We present a number of new and exciting results from the W. M. Keck 10-meter telescope diffraction-limited study of high velocity stars in the central 1"x1" of our Galaxy. Using the newly commissioned Near-Infrared Adaptive Optics Camera (NIRC2), we have obtained the first radial velocity measurement for one of the high proper motion sources at the center of the Galaxy (S0-2). When combined with new proper motion data, this results in an orbital solution with a period of a 13.2 ± 0.4 years, a central mass of 3.8 ± 0.8 \times 106 Mo, and a periapse distance and time of 140 ± 10 AU and 2002.34 ± 0.02, respectively (passing in front of the black hole). The spectrum furthermore provides information on the stellar properties (e.g., spectral type and rotation rate), offering a unique opportunity to study the astrophysics of stars in close proximity to a supermassive black hole. In addition, we also report new proper motion data and orbital solutions for 5 additional stars (S0-1, S0-4, S0-19, S0-20, and S0-21), 3 of which are newly identified. Altogether, this analysis increases the inferred dark matter density at the center of our Galaxy by three orders of magnitude compared to earlier velocity and acceleration measurements. This work not only dramatically strengthens the case for a black hole at the center of our Galaxy and rules out the alternative hypothesis of a fermion ball, but also pinpoints the dynamical center to an unprecedented ±3 mas (24 AU) and provides an independent measure of the distance to the Galactic Center.

This work was supported through NSF grant AST 99-88397 and the NSF Science and Technology Center for Adaptive Optics, managed by the University of California at Santa Cruz under cooperative agreement AST 98-76783.

[Previous] | [Session 68] | [Next]

Bulletin of the American Astronomical Society, 34, #4
© 2002. The American Astronomical Soceity.