OBLIQUITIES OF<i>KEPLER</i>STARS: COMPARISON OF SINGLE- AND MULTIPLE-TRANSIT SYSTEMS

Abstract

The stellar obliquity of a transiting planetary system can be constrained by\ncombining measurements of the star's rotation period, radius, and projected\nrotational velocity. Here we present a hierarchical Bayesian technique for\nrecovering the obliquity distribution of a population of transiting planetary\nsystems, and apply it to a sample of 70 Kepler Objects of Interest. With ~95%\nconfidence we find that the obliquities of stars with only a single detected\ntransiting planet are systematically larger than those with multiple detected\ntransiting planets. This suggests that a substantial fraction of Kepler's\nsingle-transiting systems represent dynamically hotter, less orderly systems\nthan the "pancake-flat" multiple-transiting systems.\n