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 an 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 inward 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° or 140°. Our prediction for planetary companions to HJs in stellar binaries should be testable by future observations.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- February 2017
- DOI:
- 10.3847/2041-8213/835/2/L24
- arXiv:
- arXiv:1701.04401
- Bibcode:
- 2017ApJ...835L..24H
- Keywords:
-
- binaries: general;
- gravitation;
- planet–star interactions;
- planets and satellites: dynamical evolution and stability;
- Astrophysics - Earth and Planetary Astrophysics
- E-Print:
- Accepted for publication in ApJL. 6 pages, 4 figures