Detecting activity cycles of late-type dwarfs in Kepler data

TL;DR

This paper analyzes Kepler data of active late-type dwarf stars to detect activity cycles by examining changes in rotation periods caused by differential rotation, identifying cycles in 8 out of 39 stars.

Contribution

It introduces a method using time-frequency analysis to detect stellar activity cycles through rotation period variations in Kepler light curves.

Findings

Detected activity cycles in 8 stars

Cycle periods range from 300 to 900 days

Method links differential rotation to activity cycles

Abstract

Using data of fast-rotating active dwarf stars in the Kepler database, we perform time-frequency analysis of the light curves in order to search for signs of activity cycles. We use the phenomenon that the active region latitudes vary with the cycle (like the solar butterfly diagram), which causes the observed rotation period to change as a consequence of differential rotation. We find cycles in 8 cases of the 39 promising targets with periods between of 300-900 days.