Properties of flare events based on light curves from the TESS survey^⋆

¹ College of Physics, Guizhou University, Huaxi Street 2708, 550025 Guiyang, PR China
e-mail: liy_zhang@hotmail.com
² Dept. of Physics and Astronomy and SARA, Butler University, Indianapolis, IN 46208, USA
³ Department of Physics & Astronomy Howard University, Washington, DC 20059, USA
⁴ Kechuang Industrial Development Company Limited and Gui’an Supercomputing Center, Guiyang, PR China
⁵ College of medicine, Guizhou university of traditional Chinese medicine, Guiyang 550025, PR China

Received: 21 November 2021
Accepted: 29 September 2022

Abstract

Aims. A stellar flare is a strong energy burst event. Understanding stellar flares is important for determining the properties of stellar magnetic activities. We aim to perform detailed statistical analyses on stellar flare characteristics in terms of the different stellar parameters using the light curves of the Transiting Exoplanet Survey Satellite (TESS) survey from July 2018 to October 2020.

Methods. By using repeated fitting to differentiate stellar background light curves from flare events, we precisely detected 60 810 flare events on 13 478 stars from sectors 1–30 of the TESS data and determined the flare parameters. After cross-matching our samples with the Gaia survey, we obtained more stellar parameters to determine the relationship between flare parameters and stellar parameters.

Results. The fraction of flaring stars decreases as stellar temperatures increase in the region of 2500–6500 K and stellar mass increases from 0.08 to 1.4 M_⊙. The flare energies increase as the stellar temperature and the stellar mass decrease. There is a weak relationship between flare amplitude and Ro. We also confirm that M-type stars produce flares more frequently than F-, G-, and K-type stars. We find that the proportion of flaring stars increases from M0 to M5, and decreases from M5 to M7. We obtain a power-law index of 1.83 ± 0.15 for the cumulative flare frequency distribution. The index shows a decreasing trend from F- to K-type stars, and M-type stars rise for dwarf samples. The fraction of flaring stars decreases as the vertical absolute height increases in the range 0–200 pc but this fraction is stable in the range 200–800 pc. We find that eclipsing binary stars show more frequent flares than single stars.