Aug 1, 2009
The Astrophysical Journal
The supermassive black hole at the Galactic center is surrounded by a parsec-scale star disk, with about a hundred massive young stars that move in approximately circular Keplerian orbits. Another group of roughly 20 young stars (“S-stars”) follow eccentric, randomly oriented orbits well inside the disk stars. A model is proposed to explain the S-stars. Accordingly, the stars formed originally in the parsec-scale disk through gravitational fragmentation of gas. The newly formed S-stars then migrated inward via the gravitational torques exerted by a Lin–Shu-type spiral density wave on the stars at an inner Lindblad resonance.