Superflare Rate Variations

Abstract

Photometric surveys such as the Kepler and Transiting Exoplanet Survey Satellite (TESS) missions have provided a wealth of highly accurate photometric measurements for thousands of stars, with observations from Kepler and TESS spanning a total of 15 years. These large data sets have allowed for the statistical analysis of stellar flares and their higher energy counterparts (superflares) on main and pre-main sequence stars.

Superflares have been observed on a wide variety of stars including young, magnetically active M dwarfs and even slowly rotating G dwarfs similar to the Sun. The energy released by these superflares can be several orders of magnitudes larger than even the largest flares witnessed on the Sun, and the most magnetically active stars are capable of producing superflares daily.

While there has been substantial work into measuring the statistics of superflares on these stars, there has been scarce research into determining whether the flaring activity of these superflaring stars changes over time. On the Sun, flaring rates vary over time. The emergence, evolution and decay of active regions on the Sun results in flaring rates changing over short time scales, and the overall increase and decrease

in total sunspot counts over the solar cycle also sees overall flare rates vary with the solar cycle.

This thesis aims to identify variability in the rate of occurrence of stellar flares and superflares on low mass stars, specifically G and M dwarfs, and to analyse how changes in rate may modify the statistical distributions of these flares.