Magnetic Activity of Different Types of Variable Stars Observed by TESS Mission

Abstract

The investigation of the magnetic activity of different types of variable stars holds significant implications for our understanding of the physical processes and evolution of stars. This study’s International Variable Star Index (VSX) variable star catalog was cross-matched with Transiting Exoplanet Survey Satellite (TESS) data, resulting in 26,276 labeled targets from 76,187 light curves. A total of 25,327 stellar flare events were detected, including 245 eclipsing binaries, 2324 rotating stars, 111 pulsating stars, and 629 eruptive stars. The results showed that flares from eclipsing binaries, rotating stars, eruptive stars, and pulsating stars have durations such that 90% are less than 2 h, and 91% of their amplitudes are less than 0.3. Flare events mainly occurred in the temperature range of 2000 K to 3000 K. The power-law indices of different types of variable stars were 1.72±0.025 (eclipsing binaries), 1.82±0.062 (rotating stars), 1.80±0.0116 (eruptive stars), and 1.73±0.060 (pulsating stars). Among them, the flare energy of pulsating stars is more concentrated in the high-energy range. In all samples, flare energies were distributed from 3.99×1031 erg to 6.18×1038 erg. The LAMOST DR9 low-resolution spectral survey has provided Hα equivalent widths for 398 variable stars. By utilizing these Hα equivalent widths, we have determined the stellar activity of the variable stars and confirmed a positive correlation between the flare energy and Hα equivalent width.

Keywords

• TESS
• LAMOST
• flares
• stellar activity