Activity of Young Dwarfs with Planetary Systems: EPIC 211901114 and K2–33.

Abstract

The results of an analysis of the activity of the young stars with planetary systems EPIC 211901114 and K2–33 based on observational data obtained over 70 days with the Kepler Space Telescope are presented. The rotation periods of EPIC 211901114 (8.56±0.60d) and K2–33 (6.29±0.50d) have been found. Maps of temperature inhomogeneities on the surfaces of EPIC 211901114 and K2–33 have been constructed. No relative displacements of the active regions on the stellar surface have been foundfor EPIC 211901114. The differential-rotation parameter has been estimated for K2–33, ΔΩ = 0.0039±(0.0020–0.0012) rad/day. The fractional spotted area S on the surface of EPIC 211901114 reaches about 5% of its total visible surface. For K2–33, S is 3.8% of its total visible surface, on average. On the whole, the positions of EPIC 211901114 and K2–33 on S–age, S–rotation period, and S–Rossby number diagrams match the general character of the dependence found earlier for M dwarfs. The flare activity of EPIC 211901114 and K2–33 has been studied, based on 32 flares of EPIC 211901114 and 7 flares of K2–33. The flare frequencies and amplitudes for EPIC 211901114 and K2–33 have been estimated, together with the time scales for their rise and decay. The flare energies have also been estimated, 1032.1−33.4 and 1032.2−33.3 erg for EPIC 211901114 and K2–33, respectively.