Hints for hidden planetary companions to hot Jupiters in stellar binaries

Abstract

Searches for stellar companions to hot Jupiters (HJs) have revealed that planetary systems hosting a HJ are approximately three times more likely to have a stellar companion with a semimajor axis between 50 and 2000 AU, compared to field stars. This correlation suggests that HJ formation is affected by the stellar binary companion. A potential model is high-eccentricity migration, in which the binary companion induces high-eccentricity Lidov-Kozai (LK) oscillations in the proto-HJ orbit, triggering orbital migration driven by tides. A pitfall of this `binary-LK' model is that the observed stellar binaries hosting HJs are typically too wide to produce HJs in sufficient numbers, because of suppression by short-range forces. We propose a modification to the binary-LK model in which there is a second giant planet orbiting the proto-HJ at a semimajor axis of several tens of AU. Such companions are currently hidden to observations, but their presence could be manifested by a propagation of the perturbation of the stellar binary companion inwards to the proto-HJ, thereby overcoming the barrier imposed by short-range forces. Our model does not require the planetary companion orbit to be eccentric and/or inclined with respect to the proto-HJ, but its semimajor axis should lie in a specific range given the planetary mass and binary semimajor axis, and the inclination with respect to the binary should be near $40^{\circ }$ or $140^{\circ }$. Our prediction for planetary companions to HJs in stellar binaries should be testable by future observations.

Accepted for publication in ApJL. 6 pages, 4 figures

References in corpus (8)

• Astrometric exoplanet detection with Gaia
• Hot Jupiters from Coplanar High-eccentricity Migration
• Steady-state planet migration by the Kozai-Lidov mechanism in stellar binaries
• Friends of Hot Jupiters II: No Correspondence Between Hot-Jupiter Spin-Orbit Misalignment and the Incidence of Directly Imaged Stellar Companions
• The Kozai-Lidov Mechanism in Hydrodynamical Disks
• Friends of Hot Jupiters. IV. Stellar companions beyond 50 AU might facilitate giant planet formation, but most are unlikely to cause Kozai-Lidov migration
• On the formation of hot and warm Jupiters via secular high-eccentricity migration in stellar triples
• Q in Other Solar Systems

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