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

II. 20-second cadence

¹ College of Physics, Guizhou University, 550025 Guiyang, PR China
² Department of Physics and Astronomy and SARA, Butler University, Indianapolis, IN 46208, USA
³ Department of Physics & Astronomy, Howard University, Washington, DC 20059, USA

Received: 21 October 2023
Accepted: 10 June 2024

Abstract

Aims. Stellar flares are sudden bursts of energy and are the result of magnetic activity. We used light curves from the TESS 20-second cadence survey from 2020 to 2023 to detect flare events and determine their properties.

Methods. By means of repeated fitting to distinguish stellar background light curves and flare events, we detected 32 978 flare events associated with 5463 flaring stars. Furthermore, we cross-matched our samples with the Gaia and SDSS surveys, obtaining additional stellar parameters that we used to determine the relationships between stellar and flare properties.

Results. We find that the durations of 55% of the studied flares were less than 8 minutes. The flare energies of the TESS 20-second cadence data are typically lower than those obtained from TESS 2-minute cadence data. We identify 28 425 flare events associated with 4784 flaring stars. The relationships between the flare energy and duration for both giant and main sequence stars display a consistent V-shaped distribution, with 10³⁴ erg the midway point. Stars with lower effective temperatures and masses generate more frequent flare events. In summary, it is necessary to detect more flare events with a higher time resolution, and our flare samples with 20-second cadences allowed us to discover additional new properties.