Obliquities of Kepler Stars: Comparison of Single- and Multiple-transit Systems

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Abstract

The stellar obliquity of a transiting planetary system can be constrained by combining measurements of the star’s rotation period, radius, and projected rotational velocity. Here, we present a hierarchical Bayesian technique for recovering the obliquity distribution of a population of transiting planetary systems and apply it to a sample of 70 Kepler objects of interest. With ≈95% confidence, we find that the obliquities of stars with only a single detected transiting planet are systematically larger than those with multiple detected transiting planets. This suggests that a substantial fraction of Kepler’s single-transiting systems represent dynamically hotter, less orderly systems than the “pancake-flat” multiple-transiting systems.

Author

Morton, Timothy D.; Winn, Joshua N.

Journal

Astrophysical Journal Letters

Paper Publication Date

November 2014

Paper Type

Astrostatistics