KEPLER-108: A MUTUALLY INCLINED GIANT PLANET SYSTEM

Abstract

The vast majority of well studied giant-planet systems, including the solar system, are nearly coplanar, which implies dissipation within a primordial gas disk. However, intrinsic instability may lead to planet–planet scattering, which often produces non-coplanar, eccentric orbits. Planet scattering theories have been developed to explain observed high-eccentricity systems and also hot Jupiters; thus far their predictions for mutual inclination ( I ) have barely been tested. Here we characterize a highly mutually inclined ( °), moderately eccentric ( ) giant planet system: Kepler-108. This system consists of two approximately Saturn-mass planets with periods of approximately 49 and 190 days around a star with a wide (∼300 au) binary companion in an orbital configuration inconsistent with a purely disk migration origin.