Chaotic Tides in Migrating Gas Giants: Forming Hot and Transient Warm Jupiters via Lidov-Kozai Migration

Abstract

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 timescales, provided that efficient tidal dissipation operates in the planet. We re-examine this scenario with the inclusion of dynamical tides. When the planet's orbit is in a high-eccentricity phase, the tidal force from the star excites oscillatory f-modes and r-modes in the planet. For sufficiently large eccentricity and small pericentre distance, the mode can grow chaotically over multiple pericentre passages and eventually dissipate non-linearly, drawing energy from the orbit and rapidly shrinking the semi-major 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 timescales (a few to 100 Myrs). These WJs efficiently circularize to become HJs due to their persistently small pericentre distances. Chaotic tides can also save some planets from tidal disruption by truncating the LK eccentricity oscillations, significantly increasing the HJ formation fraction for a range of planet masses and radii. Using a population synthesis calculation, we determine the characteristics of WJs and HJs produced in this scenario, including the final period distribution, orbital inclinations and stellar obliquities. Chaotic tides endow LK migration with several favorable features to explain observations of HJs. We expect that chaotic tides are also important in other flavours of high-e migration.

TOI-3362b: A Proto Hot Jupiter Undergoing High-eccentricity Tidal Migration

“…For planets that are formed at large semimajor axes and have been undergoing high-eccentricity tidal migration, we would expect to observe them only in the gray region if they are decoupled from their perturber. We also show the constant angular momentum track for planets with periapses small enough that they could excite planetary f-mode dissipation (Wu 2018;Vick et al 2019). Above the dashed line, the planet's periapse is close enough to the host star to excite f-mode oscillation which leads to rapid orbital decay from a "cold" Jupiter to a "warm" Jupiter, so we expect an absence of highly elliptical Jupiters (i.e., e > 0.9) above that line.…”

The former companion of hyper-velocity star S5-HVS1

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Study of the Mass-Ratio Distribution of Spectroscopic Binaries. II. The Boundaries of the Brown-Dwarf Desert as Seen with the APOGEE Spectroscopic Binaries

“…(i) As an outcome of binary/planetary formation, the primordial density of binaries in the P-M 2 plane was flat, with no BDD. The desert was formed by some later mechanism that caused objects found in the BDD to 'move away' from the 'restricted area' (e.g., Armitage & Bonnell 2002;Damiani & Díaz 2016;Grunblatt et al 2018;Vick et al 2019). This could happen by…”