2019/12/31 by Zuo-Lin Tu, Ming Yang, Z. J. Zhang +1 · 1 citation
Physics and Astronomy · #astro-ph.SR #astro-ph.EP
paper · pdf · doi:10.3847/1538-4357/ab6606
Accepted for Publication in ApJ. Comments are welcome. 22 pages, 10 figures, 8 tables
arxiv created 2020/01/29 · arxiv updated 2020/02/19
Superflares, as strong explosions on stars, have been well studied with the progress of space time-domain astronomy. In this work, we present the study of superflares on solar-type stars using Transiting Exoplanet Survey Satellite (\emTESS) data. 13 sectors of observations during the first year of the \em TESS mission have covered the southern hemisphere of the sky, containing 25,734 solar-type stars. We verified 1,216 superflares on 400 solar-type stars through automatic search and visual inspection with 2-minute cadence data. Our result suggests a higher superflare frequency distribution than the result from \em Kepler. The reason may be that the majority of \em TESS solar-type stars in our dataset are rapidly rotating stars. The power-law index γ of the superflare frequency distribution (dN/dE∝ E-γ) is constrained to be γ= 2.16± 0.10, which is a little larger than that of solar flares but consistent with the results from \em Kepler. Because only 7 superflares of Sun-like stars are detected, we may not give a robust superflare occurrence frequency. And four stars are accompanied by unconfirmed hot planet candidates. Therefore, superflares are possibly caused by stellar magnetic activities instead of planet-star interactions. We also find an extraordinary star TIC43472154, which exhibits about 200 superflares per year. In addition, the correlation between energy and duration of superflares (T_\text duration ∝ Eβ) is analyzed. We derive the power-law index to be β=0.42±0.01, which is a little larger than β=1/3 from the prediction according to magnetic reconnection theory.