Tilting Planets during Planet Scattering

Abstract

Observational constraints on planetary spin axis have recently become possible, and they have revealed a system that favors large spin-axis misalignment, low stellar spin–orbit misalignment, and high eccentricity. To explain the origin of such systems, we propose a mechanism that could tilt the planetary spin axis during planet–planet scattering, which is a natural outcome of in situ formation and disk migration. Specifically, we show that spin–orbit resonances could occur for a short time period during the scattering processes, and excite the misalignment of a planet’s spin axis. This typically leads to planets with large spin misalignment and a wide range of eccentricities and inclinations.