Evgeni Grishin

Hot Jupiter formation in wide binary systems

Hot Jupiters (HJ) are gas giant planets with approximately Jovian masses orbiting their host star with short orbital periods of just a few days. Their ubiquity challenges the current formation channels. HJ most likely formed elsewhere and migrated either in a disc or via high-eccentricity migration and tidal circularisation. Moreover, the significant obliquity angle (the angle between the stellar spin and planetary orbit) suggests that high-eccentricity migration is prevalent. We show that the eccentricity of the proto-HJ can be efficiently pumped by the Lidov-Kozai (LK) mechanism in the presence of an outer binary star. When the stellar binary is ultra-wide, it can be perturbed by the Galactic tidal field. We show that this ‘wide-binary’ channel is more efficient than the standard LK mechanism due to the chaotic dynamics experienced at a wide range of mutual inclinations. Using the current available wide-binary catalogue from GAIA we will estimate the formation rate of HJ from this channel.