Chaotic Dynamics of Stellar Spin in Binaries and the Production of Misaligned Hot Jupiters

TL;DR

This paper explores how gravitational interactions and chaotic dynamics during Kozai cycles can lead to misaligned hot Jupiters, highlighting the complex evolution of stellar spin axes influenced by planetary and stellar parameters.

Contribution

It demonstrates that stellar spin evolution during Kozai cycles can become chaotic due to planet-star interactions, affecting the final spin-orbit misalignment.

Findings

Chaotic evolution of stellar spin axes can occur during Kozai cycles.

Periodic islands emerge within chaotic regimes depending on system parameters.

Tidal dissipation influences the final spin-orbit misalignment angles.

Abstract

Many exoplanetary systems containing hot Jupiters are observed to have highly misaligned orbital axes relative to the stellar spin axes. Kozai-Lidov oscillations of orbital eccentricity/inclination induced by a binary companion, in conjunction with tidal dissipation, is a major channel for the production of hot Jupiters. We demonstrate that gravitational interaction between the planet and its oblate host star can lead to chaotic evolution of the stellar spin axis during Kozai cycles. As parameters such as the planet mass and stellar rotation period vary, periodic islands can appear in an ocean of chaos, in a manner reminiscent of other dynamical systems. In the presence of tidal dissipation, the complex spin evolution can leave an imprint on the final spin-orbit misalignment angles.