Effects of flares on the habitable zones of M dwarfs accessible to TESS planet detections

Abstract

AbstractPhotometric space missions such as Kepler and TESS continuously discover new exoplanets and advance the search for a second habitable world. The light curves (LCs) recorded by these telescopes also reveal signs of magnetic activity, such as star spot modulation and flares, which can influence habitability. Searching for these characteristics, we analyzed TESS LCs of 112 M dwarfs selected according to the criterion that TESS can spot planet transits over their entire habitable zone (HZ). We detected 2,532 flare events occurring on 35 stars; thus the flaring fraction is . For only of our stars, we found rotation periods. We calculated bolometric flare energies and luminosities, flare energy frequency distributions (FFDs), and the bolometric flux reaching the HZ at the peak of the flare. We estimated the effects of flaring on the atmosphere of an Earth‐like planet in the HZ from the viewpoint of both ozone depletion and the enabling of chemical reactions necessary to build ribonucleic acid (RNA). None of our targets exhibits highly energetic flares at a frequency large enough to trigger ozone depletion or RNA formation.