Further Evidence for Tidal Spin-Up of Hot Jupiter Host Stars

TL;DR

This study provides further evidence that hot Jupiters can spin up their host stars through tidal interactions, affecting stellar rotation and complicating age estimates based on stellar spin rates.

Contribution

It offers new observational evidence supporting tidal spin-up of stars by hot Jupiters, comparing stellar rotation in different planetary systems to strengthen previous findings.

Findings

Hot Jupiter hosts tend to rotate faster than similar stars with wider or less massive planets.

Tidal interactions from hot Jupiters influence stellar rotation during the main sequence.

Gyrochronology is unreliable for age estimation in hot Jupiter host stars.

Abstract

For most hot Jupiters around main-sequence Sun-like stars, tidal torques are expected to transfer angular momentum from the planet's orbit to the star's rotation. The timescale for this process is difficult to calculate, leading to uncertainties in the history of orbital evolution of hot Jupiters. We present evidence for tidal spin-up by taking advantage of recent advances in planet detection and host-star characterization. We compared the projected rotation velocities and rotation periods of Sun-like stars with hot Jupiters and spectroscopically similar stars with (i) wider-orbiting giant planets, and (ii) less massive planets. The hot Jupiter hosts tend to spin faster than the stars in either of the control samples. Reinforcing earlier studies, the results imply that hot Jupiters alter the spins of their host stars while they are on the main sequence, and that the ages of hot-Jupiter hosts cannot be reliably determined using gyrochronology.