DYNAMICAL FRICTION NEAR THE GALACTIC CENTER

Sungsoo S. Kim1, Mark Morris2, & Donald F. Figer1

1 Space Telescope Science Institute, San Martin Dr., Baltimore, MD 21286, USA
2 University of California, Los Angeles, Dept. of Physics & Astronomy, Los Angeles, CA 90095-1562, USA

E-mail contact: kim@stsci.edu

Numerical simulations of the dynamical friction suffered by a star cluster near the Galactic center have been performed with a parallelized tree code. Gerhard (2001) has suggested that dynamical friction, which causes a cluster to lose orbital energy and spiral in towards the galactic center, may explain the presence of a cluster of very young stars in the central parsec, where star formation is thought to be prohibitively difficult owing to strong tidal forces. The clusters modeled in our simulations have an initial total mass of 105-106 Msun and initial galactocentric radii of 2.5-30 pc. We have identified a few simulations in which dynamical friction indeed brings a cluster to the central parsec. For this to be possible, the cluster should either initially have a very dense core (>~ 108 Msun pc-3) or retain a significant mass of gas from its parent cloud (making total cluster mass of ~106 Msun). The initial segregation of massive stars in the cluster core can help account for the observed distribution of HeI stars in the central parsec.