Stellar disk in the Galactic center: A remnant of a dense accretion disk?

Observations of the Galactic center revealed a population of young massive stars within 0.4 pc from Sgr A*-the presumed location of a supermassive black hole. The origin of these stars is a puzzle as their formation in situ should be suppressed by the black hole's tidal field. We find that out of 13 stars whose three-dimensional velocities have been measured by Genzel et al., 10 lie in a thin disk. The half-opening angle of the disk is consistent with zero within the measurement errors and does not exceed 10degrees. We propose that a recent burst of star formation has occurred in a dense gaseous disk around Sgr A*. Such a disk is no longer present because, most likely, it has been accreted by the central black hole. The three-dimensional orbit of S2, the young star closest to Sgr A*, has been recently mapped out with high precision. It is inclined to the stellar disk by 75degrees. We find that the orbit should undergo Lense-Thirring precession with the period of similar to(6/a) x 10(6) yr, where a < 1 is the dimensionless spin of the black hole. Therefore, it is possible that originally the S2 orbit lay in the disk plane. The Lense-Thirring precession can turn the S2 orbit by 75° if a > 0.2(t(s2)/6 x 10(6) yr)(-1), where t(s2) is the age of S2.