Testing the Rotation-Activity Relation with the Hyades and Praesepe

As the nearest open cluster to the Sun, the Hyades is an important benchmark for calibrating stellar properties such as rotation and magnetic activity. Its proximity, however, means that cluster members are scattered across a wide area of the sky; previous studies of rotation relied on wide-area surveys designed to discover transiting exoplanets. I will present rotation periods measured using K2 data of the Hyades, including the first rotation periods of less than 1 day for cluster members and for fully convective Hyads. Discrepancies between Hyades data and gyrochronology models imply that we still do not fully understand how magnetic fields affect stellar spin-down. I will discuss how we can use the Hyades and the co-eval Praesepe cluster to test theories of stellar magnetic fields.Presented in the splinter session "Star Clusters From Space, From the Ground, and Over Time