Activity of an M4.5 Hyades Dwarf with a Planetary Systemстатья
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Дата последнего поиска статьи во внешних источниках: 17 октября 2017 г.
Аннотация: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 ΔΩ = 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(RX) = −4.20.