Kepler - 411 stellar activity from the modeling of planetary transits.
Abstract
Kepler-411 is a K2V-type star with an average rotation period of 10.52
days, radius of 0.79 Rsun and mass of 0.83 Msun. This active star has at
least four planets, three of them eclipse the star, the three larger
planets are mini Neptunes with radii of 2.2, 3.47 and 3.46 Earth radii,
and periods of 3.0, 7.8 and 58.0 days, respectively. This star was
observed by the Kepler satellite for about 600 days showing a total
number of 195 transit for planet Kepler-411 b, 76 transits Kepler-411c
and 10 transits for planet Kepler-411d. When a planet transits its host
star, it may occult a spot causing a detectable signal in the light
curve. In this work we apply the model described in Silva (2003), to
characterize the starspots, which resulted in the detection of a total
of 45 spots in Kepler-411b, 143 spots in Kepler-411c transits and 10
spots in Kepler-411d transits. Analysis of the spots detected on the
different transit latitudes of these planets yields a differential shear
of 0.050 rd/d or a relative differential rotation of 8.3%, assuming a
solar like rotation profile. Also, a total of 66 flares and superflares
were detected on the light curve. Here, we discuss the relationship
between the size and temperature of the starspots with statistical data
on flares and superflares.