Rotation Periods, Variability Properties and Ages for Kepler Exoplanet Candidate Host Stars

TL;DR

This study reports rotation periods, variability, and ages for about 950 Kepler exoplanet host stars, revealing diverse stellar behaviors, potential spin-orbit misalignments, and signs of tidal interactions with close-in planets.

Contribution

It provides the first large-scale analysis of stellar rotation and variability for Kepler exoplanet hosts, including implications for system evolution and star-planet interactions.

Findings

Wide dispersion in variability amplitudes among stars.

Identification of systems with possible spin-orbit misalignment.

Detection of systems with rotation periods matching planetary orbital periods.

Abstract

We report rotation periods, variability characteristics, gyrochronological ages for ~950 of the Kepler Object of Interest host stars. We find a wide dispersion in the amplitude of the photometric variability as a function of rotation, likely indicating differences in the spot distribution among stars. We use these rotation periods in combination with published spectroscopic measurements of vsini and stellar parameters to derive the stellar inclination in the line-of-sight, and find a number of systems with possible spin-orbit misalignment. We additionally find several systems with close-in planet candidates whose stellar rotation periods are equal to or twice the planetary orbital period, indicative of possible tidal interactions between these planets and their parent stars. If these systems survive validation to become confirmed planets, they will provide important clues to the evolutionary history of these systems.