We perform a study of stellar flares for the 24,809 stars observed with 2 minute cadence during the first two months of the TESS mission.
Flares may erode exoplanets’ atmospheres and impact their habitability, but might also trigger the genesis of life around small stars. TESS provides a new sample of bright dwarf stars in our galactic neighborhood, collecting data for thousands of M-dwarfs that might host habitable exoplanets. Here, we use an automated search for flares accompanied by visual inspection. Then, our public allesfitter code robustly selects the appropriate model for potentially complex flares via Bayesian evidence. We identify 763 flaring stars, 632 of which are M-dwarfs. Among 3247 flares in total, the largest superflare increased the stellar brightness by a factor of 15.7. Bolometric flare energies range from 10^31 to 10^38.7 erg, with a median of 10^32.8 erg.
Furthermore, we study the flare rate and energy as a function of stellar type and rotation period. We solidify past findings that fast rotating M-dwarfs are the most likely to flare, and that their flare amplitude is independent of the rotation period. Finally, we link our results to criteria for prebiotic chemistry, atmospheric loss through coronal mass ejections, and ozone sterilization. Four of our flaring M-dwarfs host exoplanet candidates alerted on by TESS, for which we discuss how these effects can impact life.
With upcoming TESS data releases, our flare analysis can be expanded to almost all bright small stars, aiding in defining criteria for exoplanet habitability.
Maximilian N. Günther, Zhuchang Zhan, Sara Seager, Paul B. Rimmer, Sukrit Ranjan, Keivan G. Stassun, Ryan J. Oelkers, Tansu Daylan, Elisabeth Newton, Edward Gillen, Saul Rappaport, George R. Ricker, David W. Latham, Joshua N. Winn, Jon M. Jenkins, Ana Glidden, Michael Fausnaugh, Alan M. Levine, Jason A. Dittmann, Samuel N. Quinn, Akshata Krishnamurthy, Eric B. Ting (Submitted on 2 Jan 2019)
Comments: 19 pages, 10 figures, 2 tables, submitted to AAS journals Subjects: Earth and Planetary Astrophysics (astro-ph.EP) Cite as: arXiv:1901.00443 [astro-ph.EP] (or arXiv:1901.00443v1 [astro-ph.EP] for this version) Submission history From: Maximilian Günther [v1] Wed, 2 Jan 2019 16:18:56 UTC (918 KB) https://arxiv.org/abs/1901.00443 Astrobiology