Stellar velocities and the mass distribution in the Galactic center

Radial velocities have been measured for 43 stars within 6.5 pc of the Galactic center. The stellar velocity dispersion of 75 km/s is virtually independent of radius from 0.36 pc to 6 pc, indicating that an extended mass distribution is being sampled over this entire range. The stellar velocities do not show the increase within 2 pc of Sgr A(asterisk) found for the gas, suggesting that the gas motions may be affected by nongravitational forces. If the core radius of the stellar distribution is about 0.1 pc, these data require no unseen mass within the Galactic center; however, if the core radius is about 0.6 pc, an unseen mass of 2,000,000 solar masses may still exist. 28 references