Activity of the Early M Dwarf Kepler-45 from Starspot and Facula Mapping

Temporal mapping of starspots & faculae details surface activity  for the faint hot Jupiter hosting M1V dwarf Kepler-45. Results are consistent with solar-type spot activity, differential rotation, and rapid activity cycles observed for other red dwarfs.  Adopting a solar-type differential rotation profile,  mapping yields a rotation period of 15.520 ± 0.025 d at  transit latitude -33˚. From the mean stellar rotation of 15.762 d, a rotational shear of 0.031 ± 0.004 rad/d, or a relative differential rotation of 7.8 ± 0.9 %, is estimated. The surface rotational shear is consistent with observations and theoretical modelling of other early M dwarfs. Starspot and facular temperatures contrast a few hundred degrees relative to the quiet photosphere, similar with other early M dwarfs. A short-term activity cycle of about 295 d  is reminiscent of those seen for other cool dwarfs.