科研之友
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摘要
An analysis of the activity of the Hyades M4.5 dwarf EPIC 210490365, K2-25 (2MASS J04130560+1514520), based on observational data obtained with the Kepler Space Telescope is presented. This dwarf has a Neptune-type planet. The continuous evolution of active regions on the surface of K2-25 is traced over 70 days. The brightness changes of the star display a fairly stable nature. The rotation period of K2-25 is 1.878 +/- 0.030 day. Maps of temperature inhomogeneities on the surface of K2-25 are constructed for 37 sets of observations. All these maps show concentrations of spots at two longitudes, with more active region having the larger area. The total spotted surface area S is, on average, 2.6% of the total visible surface of the star. The estimated differential rotation speed of the star is Delta Omega = 0.0071 +/- 0.002 rad/day. The positions of K2-25 in S-age, S-rotation period, and S-Rossby number diagrams are consistent with the general trends of these dependences established earlier for M dwarfs. The derived Rossby number for K2-25, Ro = 0.36, is used to estimate the star's X-ray luminosity to be log(R-X) = -4.20.
- 出版日期2017-10
