Starspot Distribution and Flare Events in Two Young Low-mass Stars Using TESS Data

Abstract Wide-field high-precision photometric observations such as the Transiting Exoplanet Survey Satellite (TESS) allowed the investigation of the stellar magnetic activity of cool stars. M dwarf starspots and stellar flares are the main indicators of magnetic activity. The present study focuses on modeling light curves (LCs) to analyze the distribution and characteristics of starspots, e.g., location, temperature, and spot size. The TESS LCs of two selected young M dwarfs, i.e., GJ 182 and 2MASS J05160212+2214528, were reconstructed using the Best rAndom StarSpots Model calculAtioN software, obtaining a three-spot model for GJ 182 and two-spot model for 2MASS J05160212+2214528, describing their LCs. For GJ 182, the mean spot temperature was estimated to be approximately 3279 K, covering 5%–8.5% of the stellar surface, while for 2MASS J05160212+2214528, the average spot temperature was approximately 2631 K, with a mean spottedness of about 5.4%. Using the 2 minute cadence LC data, we identified and analyzed 48 flare events from GJ 182, while no flares were detected in 2MASS J05160212+2214528. The estimated bolometric flare energy ranges from 10 32 to 10 35 erg, while in the TESS bandpass, it ranges from 10 31 to 10 33 erg. We derived the power-law index of −1.53 ± 0.12 and −1.86 ± 0.22 for flare frequency distribution in sectors 5 and 32, respectively, in the flare energy range 10 33 –10 35 erg, consistent with previous studies for M dwarfs. A positive linear correlation between flare energy and duration was found with a slope of 0.67 ± 0.02, suggesting a similar mechanism followed by stellar superflares and solar flares. By assuming the similarities with solar flares, we also estimated a lower limit of the magnetic field strength of around 12–232 G to produce such superflare events.