Origins of Hot and Warm Jupiters from the Stellar Obliquity Distribution

The obliquity of a star, or the angle between its spin axis and the orbit normal of its companion planets, provides a unique constraint on that system’s evolutionary history. In contrast with the solar system, where the Sun’s equator is nearly aligned with its companion planets, many hot Jupiter systems have been discovered with large stellar obliquities, hosting planets on polar or retrograde orbits. We demonstrate that the observed stellar obliquity distribution, combined with tidal dissipation from star-planet interactions, points towards high-eccentricity migration as the primary hot Jupiter formation mechanism. We also present the first results from the Stellar Obliquities in Long-period Exoplanet Systems (SOLES) survey, which is extending the sample of stellar obliquity measurements to include systems with wide-orbiting planets that are more representative of the primordial obliquity distribution. We conclude with a new, fully consistent paradigm for hot and warm Jupiter formation.