Radial velocities of stars in the Galactic Center

The high-resolution (R={lamda}/{Delta}{lambda}>=14000) observations allow the most accurate radial velocity and acceleration measurements of the stars in the central parsec of the Galaxy. Detected stars can be divided into three groups based on the CO absorption band heads at ~2.2935um and the HeII lines at ~2.0581 and ~2.112, 2.113um: cool, narrow-line hot, and broad-line hot.

The radial velocities of the cool, late-type stars have approximately a symmetrical distribution with its center at ~-7.8+/-10.3km/s and a standard deviation ~113.7+/-10.3km/s. Although our statistics are dominated by the brightest stars, we estimate a central black hole mass of (3.9+/-1.1)x10^6^M_{sun}_, consistent with current estimates from complete orbits of individual stars. Our surface density profile and the velocity dispersion of the late-type stars support the existence of a low-density region at the Galactic center suggested by earlier observations.