Kepler main-sequence solar-like stars: surface rotation and magnetic-activity evolution

TL;DR

This paper reviews how Kepler data has advanced understanding of surface rotation and magnetic activity in main-sequence solar-like stars, revealing key evolutionary transitions and a notable intermediate-rotation gap.

Contribution

It synthesizes Kepler observations with stellar evolution theory, highlighting new insights into rotation and magnetic activity transitions in solar-like stars.

Findings

Identification of the intermediate-rotation gap in Kepler data

Correlation of rotation gap with X-ray luminosity data

Insights into the evolution of stellar magnetic activity

Abstract

While the mission's primary goal was focused on exoplanet detection and characterization, Kepler made and continues to make extraordinary advances in stellar physics. Stellar rotation and magnetic activity are no exceptions. Kepler allowed for these properties to be determined for tens of thousands of stars from the main sequence up to the red giant branch. From photometry, this can be achieved by investigating the brightness fluctuations due to active regions, which cause surface inhomogeneities, or through asteroseismology as oscillation modes are sensitive to rotation and magnetic fields. This review summarizes the rotation and magnetic activity properties of the single main-sequence solar-like stars within the Kepler field. We contextualize the Kepler sample by comparing it to known transitions in the stellar rotation and magnetic-activity evolution, such as the convergence to the rotation sequence (from the saturated to the unsaturated regime of magnetic activity) and the Vaughan-Preston gap. While reviewing the publicly available data, we also uncover one interesting finding related to the intermediate-rotation gap seen in Kepler and other surveys. We find evidence for this rotation gap in previous ground-based data for the X-ray luminosity. Understanding the complex evolution and interplay between rotation and magnetic activity in solar-like stars is crucial, as it sheds light on fundamental processes governing stellar evolution, including the evolution of our own Sun.