The rotation–activity relation of M dwarfs: From K2 to TESS and PLATO

Abstract

Studies of the rotation–activity relation of late-type stars are essential to enhance our understanding of stellar dynamos and angular momentum evolution. We study the rotation–activity relation with K2 for M dwarfs, where it is especially poorly understood. We analyzed the light curves of all bright and nearby M dwarfs form the Superblink proper motion catalog that were in the K2 field of view. Using a sample of 430 M dwarfs observed in campaigns C0–C19 in long-cadence mode, we determined the rotation period and a wealth of activity diagnostics. Our study of the rotation–activity relation based on photometric activity indicators confirmed the previously published abrupt change of the activity level at a rotation period of ∼10 days. Our sample, which is more than three times larger, increases the statistical significance of this finding.