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We present new proper motions from the 10 m Keck telescopes for a puzzlingpopulation of massive, young stars located within 3.5" (0.14 pc) of thesupermassive black hole at the Galactic Center. Our proper motion measurementshave uncertainties of only 0.07 mas/yr (3 km/s), which is ~7 times better thanprevious proper motion measurements for these stars, and enables us to measureaccelerations as low as 0.2 mas/yr^2 (7 km/s/yr). Using these measurements,line-of-sight velocities from the literature, and 3D velocities for additionalyoung stars in the central parsec, we constrain the true orbit of eachindividual star and directly test the hypothesis that the massive stars residein two stellar disks as has been previously proposed. Analysis of the stellarorbits reveals only one of the previously proposed disks of young stars using amethod that is capable of detecting disks containing at least 7 stars. Thedetected disk contains 50% of the young stars, is inclined by ~115 deg from theplane of the sky, and is oriented at a position angle of ~100 deg East ofNorth. Additionally, the on-disk and off-disk populations have similar K-bandluminosity functions and radial distributions that decrease at larger projectedradii as \propto r^-2. The disk has an out-of-the-disk velocity dispersion of28 +/- 6 km/s, which corresponds to a half-opening angle of 7 +/- 2 deg, andseveral candidate disk members have eccentricities greater than 0.2. Ourfindings suggest that the young stars may have formed in situ but in a morecomplex geometry than a simple, thin circular disk.

A Disk of Young Stars at the Galactic Center as Determined by Individual Stellar Orbits