Starspots and Flares are Generally Not Correlated

TL;DR

This study analyzes a large dataset of stellar flares and spots, finding no correlation between flare activity and spot visibility, contrasting with the Sun's behavior.

Contribution

It introduces a new algorithm, extsc{toffee}, to detect stellar flares and demonstrates that flares are not preferentially associated with starspots on other stars.

Findings

Flares occur equally during bright and dim phases of stars.

No correlation between flare rate and spot occurrence on other stars.

Large dataset of over 218,000 flares analyzed.

Abstract

Sunspots and solar flares are two different manifestations of magnetic activity on the surface of the Sun. On the Sun, flares typically occur close to spots. In this paper we test this the connection between spots and flares on other stars. We detect 218,386 stellar flares on 14,163 spotted stars using a new algorithm called \textsc{toffee}. Inhomogeneous spot distributions mean that as stars rotate they become brighter when less spots are facing the observer, and dimmer when more spots are facing the observer. We determine that flares occur when the star is brighter $49.97\pm 0.21\%$ of the time, i.e. there is an equal preference for the flares to occur when the star is relatively bright or dim. We therefore find no evidence for a correlation between flare rate and spot occurrence, contrary to what is seen on the Sun.