Flare Activity and Magnetic Feature Analysis of the Flare Stars

Abstract

We analyze the light curve of 1740 flare stars to study the relationship between the magnetic feature characteristics and the identified flare activity. Coverage and stability of magnetic features are inspired by rotational modulation of light curve variations and flare activity of stars are obtained using our automated flare detection algorithm. The results show that (i) Flare time occupation ratio (or flare frequency) and total power of flares increase by increasing relative magnetic feature coverage and contrast in F-M type stars (ii) Magnetic feature stability is highly correlated with the coverage and the contrast of the magnetic structures as this is the case for the Sun (iii) Stability, coverage and contrast of the magnetic features, time occupation ratio and total power of flares increases for G, K and M-type stars by decreasing Rossby number due to the excess of produced magnetic field from dynamo procedure until reaching to saturation level.

Flare Activity and Magnetic Feature Analysis of the Flare Stars. II. Subgiant Branch

“…For general comparison between the magnetic activity of the MS stars which was reported in paper I and the SGB stars that are discussed in this paper, the average values of the magnetic parameters and flare indexes for these two evolutionary states are given in table 2. In order to avoid the effect of different sample selection in the MS and SGB Goodarzi et al (2019).…”

“…In order to detect flare spikes automatically, we use our automated routine which was described in Goodarzi et al (2019). In this routine, first we extract gradual component (F G ) that is the main fluctuation component of the light curve due to the rotation modulation by the magnetic features, see middle panels of figure 1.…”

“…In our previous paper (Goodarzi et al (2019), hereafter paper I) we analyzed 1740 main-sequence stars from F, G, K and M spectral types and studied relationship between the magnetic feature characteristics and the identified flare activity. In this paper, we focus on the magnetic properties and flare activity of the subgiant stars and compare the results with the main-sequence.…”

“…The average value of parameters for the Main sequence stars is computed from the table.1 ofGoodarzi et al (2019).…”

Characteristic time of stellar flares on Sun-like stars

“…Recently, the study of solar-stellar connection has been a prominent field, developing into an interdisciplinary research concerning both solar physics and stellar physics (Dupree 2003;Shibata et al 2013;Brun & Browning 2017;Choudhuri 2017, and references therein). The long-term Kepler stellar light-curve observations greatly facilitate this field of studies (e.g., He et al 2015He et al , 2018Karoff et al 2016;Mehrabi et al 2017;Goodarzi et al 2019;Reinhold et al 2020;Zhang et al 2020a,b). Among the topics, the homogeneity of solar-stellar flares is one appealing subject.…”