A CHARA Array Long Baseline Interferometric Survey of Circumstellar Disks of Be Stars

We present the first spatially resolved observations of circumstellar envelopes of 24 bright northern Be stars. This survey was performed with the CHARA Array interferometer in the K-band at intermediate and long baselines. The interferometric visibilities are well fitted by an optically thick disk model where the gas density decreases with the radius as a power-law. Physical and geometrical parameters, such as the density profile, the inclination, and the position angle of the circumstellar disks, are determined, and the disk density exponent is found to range between n similar to 2.4-3.2, which is consistent with previous IRAS measurements. We also find that the thick disk model reproduces well the simultaneously observed disk IR-continuum excess. By combining the projected rotational velocity of the Be star with the disk inclination derived from interferometry, we provide estimates of the equatorial rotational velocities of these Be stars.