On the formation of hot and warm Jupiters via secular high-eccentricity migration in stellar triples

Abstract

Hot Jupiters (HJs) are Jupiter-like planets orbiting their host star in tight orbits of a few days. They are commonly believed not to have formed in situ, requiring inwards migration towards the host star. One of the proposed migration scenarios is secular high-eccentricity or high-e migration, in which the orbit of the planet is perturbed to high eccentricity by secular processes, triggering strong tidal evolution and orbital migration. Previous theoretical studies have considered secular excitation in stellar binaries. Recently, a number of HJs have been observed in stellar triple systems. In the latter, the secular dynamics are much richer compared to stellar binaries, and HJs could potentially be formed more efficiently. Here, we investigate this possibility by modeling the secular dynamical and tidal evolution of planets in two hierarchical configurations in stellar triple systems. We find that the HJ formation efficiency is higher compared to stellar binaries, but only by at most a few tens of per cent. The orbital properties of the HJs formed in the simulations are very similar to HJs formed in stellar binaries, and similarly to studies of the latter we find no significant number of warm Jupiters. HJs are only formed in our simulations for triples with specific orbital configurations, and our constraints are approximately consistent with current observations. In future, this allows to rule out high-e migration in stellar triples if a HJ is detected in a triple grossly violating these constraints.

Secular dynamics of binaries in stellar clusters – I. General formulation and dependence on cluster potential

“…One of the most interesting recent applications of secular dynamics has been the possibility of substantial shrinking of binary orbits by LK cycles with dissipative effects. Such applications include the origin of hot Jupiters (Fabrycky & Tremaine 2007;Naoz et al 2011;Petrovich 2015;Hamers 2017), formation of blue stragglers (Perets & Fabrycky 2009;Knigge et al 2009), white-dwarf mergers (Thompson 2011;Toonen et al 2018), and compact-object binary mergers in globular or nuclear star clusters (Antognini et al 2014;Rodriguez et al 2015;Naoz 2016;Silsbee & Tremaine 2017;Petrovich & Antonini 2017;Leigh et al 2018). Binary evolution driven by cluster tides explored in our work represents a different evolutionary scenario that may lead to similar outcomes (without invoking a nearby third companion).…”

Binary Mergers near a Supermassive Black Hole: Relativistic Effects in Triples

“…(4) implies that S 3 precesses around L out at the rate Ω LoutS3 L out /S 3 . As shown in [44] in a different context, the variation ofL out can significantly affect LK eccentricity excitation when Ω LoutS3 becomes comparable to Ω LK . Fig.…”

“…Since Ω As explained in [44], when γ ∼ 1, an inclination resonance generates larger I even from a small initial I 0 , leading to a wider range of initial inclinations for extreme eccentricity excitation. Fig.…”

“…We see that including Effects I-II (purple dots) can dramatically widen the eccentricity excitation window. As γ approaches unity with increasing m 3 , overlapping inclination and LK resonances give rise to the widespread chaos [44], causing systems with modest I 0 to attain extreme eccentricity growth. When e max becomes sufficiently close to unity, the timescale the inner BHB spends in high-e in phase (t LK 1 − e 2 max ; [51]) becomes less than the period of the outer binary, the DA approximation breaks down, and the system enters semi-secular regime [52,53].…”

Hot Jupiters Driven by High-eccentricity Migration in Globular Clusters

“…High-eccentricity (high-e) migration around field stars has been widely studied. The possible eccentricity excitation mechanisms include planet-planet scattering (Rasio & Ford 1996;Chatterjee et al 2008;Jurić & Tremaine 2008;Nagasawa et al 2008;Beaugé & Nesvorný 2012); Lidov-Kozai (LK) oscillations (Lidov 1962;Kozai 1962) in binary-star systems (Wu & Murray 2003;Fabrycky & Tremaine 2007;Naoz et al 2012;Petrovich 2015a;Anderson et al 2016;Petrovich & Tremaine 2016;Hamers 2017b), triple-star systems (Hamers 2017a;Grishin et al 2017), and multiplanet systems (Petrovich 2015b;Xue & Suto 2016); and secular chaos in multiplanet systems Hamers et al 2017). Although many authors have studied the dynamics of planets in open clusters and GCs (e.g., Sigurdsson 1992;de La Fuente Marcos & de La Fuente Marcos 1997;Bonnell et al 2001;Davies & Sigurdsson 2001;Fregeau et al 2006;Spurzem et al 2009;Malmberg et al 2011;Boley et al 2012;Chatterjee et al 2012;Parker & Quanz 2012;Hao et al 2013;Liu et al 2013;Li & Adams 2015;Wang et al 2015;Zheng et al 2015;Cai et al 2017), the interplay between perturbations from passing stars and dissipative planetary tides has scarcely been investigated.…”