Observational imprints of tidal internal gravity wave dissipation in star-planet systems

TL;DR

This study investigates how internal gravity wave dissipation within stars influences the orbital evolution and observed characteristics of hot Jupiter systems, revealing its significant role in planetary engulfment and system architecture.

Contribution

It demonstrates that internal gravity wave dissipation explains stellar rotation enhancements and the distribution of hot Jupiters, providing a new understanding of star-planet interactions.

Findings

Enhanced stellar rotation can result from hot Jupiter engulfment due to gravity wave damping.

Older hot Jupiter systems show a steep decline in orbital periods, unlike younger systems.

Up to 13% of stars that hosted hot Jupiters may have engulfed them, influenced by gravity wave dissipation.

Abstract

Tidal interactions play a crucial role in the orbital evolution of close-in star-planet systems. There are numerous manifestations of tides, including planetary orbital migration, breaking resonant chains, tidal heating, orbital circularization, spin-orbit alignment, and stellar and planetary spin synchronization. In the present study, we focus on the dissipation of internal gravity waves within stars. We examine two mechanisms: wave breaking in stars with radiative cores and magnetic wave conversion in stars with convective cores. Applying tidal prescriptions modelling these processes, we demonstrate that the enhanced stellar rotation of both TOI-2458 and GJ 504 can be explained by the previous engulfment of a hot Jupiter caused by gravity wave damping. Furthermore, we show that the observed population of hot Jupiters can be divided into two distinct subsamples: those that are too young for gravity wave dissipation and those where it is ongoing. These subsamples exhibit qualitatively different orbital period distributions: young systems have a uniform distribution, while older systems show a steep decline at short orbital periods. Using a population synthesis approach, we successfully reproduce the main features of the older hot Jupiter sample based on the distribution of the younger systems. According to our estimates, up to 13% of the main-sequence stars within the mass range [0.7,1.5] $M_{\odot}$ that once hosted a hot Jupiter may have since engulfed it. Our results highlight the key role of internal gravity wave dissipation in shaping the orbital architectures of hot Jupiter systems.