Starspot Modeling and Flare Analysis on Selected Main-sequence M-type Stars

Abstract

We studied the light curves of GJ 1243, YZ CMi, and V374 Peg, as observed by TESS, for the presence of stellar spots and stellar flares. One of the main goals was to model the light curves of the spotted stars to estimate the number of spots, along with their parameters, using our original BASSMAN software. The modeled light curves were subtracted from the observations to increase the efficiency of the flare detection. The flares were detected automatically with our new dedicated software, WARPFINDER. We estimated the presence of two spots on GJ 1243, with a mean temperature of about 2800 K and a spottedness varying between 3% and 4% of the stellar surface, and two spots on V374 Peg, with a mean temperature of about 3000 K and a spottedness of about 6% of the stellar surface. On YZ CMi, we found two different models for two light curves separated in time by 1.5 yr. One of them was a three-spot model, with a mean temperature of about 3000 K and a spottedness of about 9% of the stellar surface. The second was a four-spot model, with a mean temperature of about 2800 K and a spottedness of about 7% of the stellar surface. We tested whether the flares were distributed homogeneously in phase and where there was any correlation between the presence of spots and the distribution of the flares. For YZ CMi, one spot was in anticorrelation with the distribution of the flares, while GJ 1243 shows the nonhomogeneous distribution of flares.