Observed Rate Variation in Superflaring G-type Stars

TL;DR

This study investigates the variability in superflare occurrence rates on G-type stars using TESS data, revealing significant rate changes in a subset of stars and exploring underlying causes.

Contribution

It introduces a Bayesian Blocks-based method to detect superflare rate variations on G-type stars, a novel application in stellar flare analysis.

Findings

Seven stars show significant superflare rate changes.

Most stars do not exhibit detectable rate variation.

The low number of variable stars suggests rarity or detection limits.

Abstract

Flare occurrence on the Sun is highly variable, exhibiting both short term variation due to the emergence and evolution of active regions, and long-term variation from the solar cycle. On solar-like stars, much larger stellar flares (superflares) have been observed, and it is of interest to determine whether observed rates of superflare occurrence exhibit similar variability to solar flares. We analyse 274 G-type stars using data from the Transiting Exoplanet Survey Satellite (TESS) and identify seven stars which exhibit statistically significant changes in the rate of superflare occurrence by fitting a piecewise constant-rate model with the Bayesian Blocks algorithm (Scargle et al 2012; arXiv:1207.5578). We investigate the properties of these stars and their flaring rates, and discuss the possible reasons for the low number of stars with detectable rate variation.