Rotation of Young Very Low Mass Objects

Abstract

We present our large sample of photometric rotation periods for VLM objects in young open clusters. Based on these periods, we investigate the mass and age dependence of rotation, and find a) a significant lack of slow rotators, b) exponential rotational braking, and c) no significant influence of disk-locking for ages > 3Myr. Using additional information about disks and surface activity, we conclude that VLM objects probably have inefficient disk-locking and small-scale magnetic fields. We demonstrate the importance of near- and mid-infrared observations with high sensitivity for a more detailed interpretation of our observed rotation periods.