ITC Seminar - Michelle Vick (Cornell)


Monday, April 22, 2019, 12:00pm to 1:00pm


Chaotic Dynamical Tides in Eccentric Gas Giants

High-eccentricity migration is an important channel for the formation of hot Jupiters (HJs). In particular, Lidov–Kozai (LK) oscillations of orbital eccentricity/inclination induced by a distant planetary or stellar companion, combined with tidal friction, have been shown to produce HJs on Gyr time-scales. We re-examine this scenario with the inclusion of chaotic dynamical tides. When the planet’s orbit is in a high-eccentricity phase, the tidal force from the star excites oscillatory f-modes and i-modes in the planet. For sufficiently large eccentricity and small pericenter distance, the modes can grow chaotically over multiple pericenter passages and eventually dissipate non-linearly, drawing energy from the orbit and rapidly shrinking the semimajor axis. We study the effect of such chaotic tides on the planet’s orbital evolution. We find that this pathway produces very eccentric (e ≳ 0.9) warm Jupiters (WJs) on short time-scales (a few to 100 Myr). These WJs efficiently circularize to become HJs due to their persistently small pericenter distances. Chaotic tides can also save some planets from tidal disruption by truncating LK eccentricity oscillations, significantly increasing the HJ formation fraction for a range of planet masses and radii. Chaotic tides endow LK migration and other flavors of high-e with several favorable features to explain observations of HJs.
See also: Seminars, 2018 - 19