MPS Seminar: Sun-like stars produce superflares roughly once per century (Valeriy Vasilyev)

Can superflares happen on the Sun and how often do they occur? One possible way to answer this question is to compare solar and stellar flare records. In recent years, stellar flares have been detected through data collected by large photometric surveys. However, these detections were based on the analysis of light curves and did not take into account potential sources of contamination, such as background stars or small solar system objects appearing in the same aperture as the primary target. Both scenarios can mimic flares in the light curves and so distort the true flare statistics. In this study, we applied a new method for identifying the true flare sources in large photometric surveys, using both light curves and CCD images, to a new solar-stellar comparison sample, which is much bigger than previous samples and more representative of the Sun. We detected 2889 superflares on 2527 out of 56450 Sun-like stars observed by the Kepler space telescope. Our research reveals that solar-like stars exhibit superflares at a rate nearly two orders of magnitude higher than previously reported. Superflares with energies exceeding 1e34 erg happen approximately once every century on stars that have temperatures and variability similar to the Sun. Our results show that the stellar superflare frequency distribution is consistent with the observed solar flare frequency distribution extrapolated to larger energies, indicating a common mechanism behind the generation of flares.