Photometric Observations of Flares on AD Leo from GWAC-F30 and TESS

Abstract

We observed active M dwarf star AD Leo for 146 hr in photometry by GWAC-F30 and also analyzed 528 hr of photometric data of the star from the Transiting Exoplanet Survey Satellite (TESS). A total of 9 and 70 flares are detected from GWAC-F30 and TESS, respectively. Flare durations, amplitudes and energies are calculated. The distributions of the three properties and flare frequency distributions (FFDs) are given. Within the same energy range of flares, the FFDs of AD Leo obtained in this research and the previous study are basically consistent, which suggests that the magnetic activity of this star has not significantly changed compared to decades ago. Comparing with the average FFD of M-type stars, AD Leo’s FFD is twice higher, indicating that its magnetic activity is more active than that of the average level of the M-type. Based on the TESS light curve, AD Leo’s rotation period is calculated as days, supporting the result given in previous research. During the decay phase of the most energetic flare from TESS, we identified quasi-periodic pulsations and determined a 26.5 minute oscillation period, which is currently the longest period for AD Leo, suggesting that long periodic physical processes existed during the flare of this star.