Kepler-17 long-term photometry

The latitudinal differential rotation is of solar type, that is, with the equator rotating faster than the poles. We estimate a minimum relative amplitude {DELTA}{OMEGA}/{OMEGA} between ~0.08+/-0.05 and 0.14+/-0.05, our determination being affected by the finite lifetime of individual starspots and depending on the adopted spot model parameters. We find marginal evidence of a short-term intermittent activity cycle of ~48-days and an indication of a longer cycle of 400-600 days characterized by an equatorward migration of the mean latitude of the spots as in the Sun.

The rotation of Kepler-17 is likely to be significantly affected by the tides raised by its massive close-by planet. We confirm the reliability of maximum-entropy spot models to map starspots in young active stars and characterize the activity and differential rotation of this young Sun-like planetary host.