Testing Models for Stellar Magnetic Dynamos with Slow Rotators in Praesepe

In solartype stars, rotational shear at the tachocline is thought to power adynamo, generating a magnetic field that heats the star.s corona, which producesXrays. Xray flux and rotation rates measurements therefore provide insightinto the strength of the underlying magnetic field and its dependence onrotation. But this rotationactivity relation remains unconstrained for theslowest rotators (i.e., Rossby number > 0.8). We propose to observe six700Myrold solartype slowly rotating Praesepe stars, for a total of 157 ks ofexposure with the EPIC camera. Our data will provide invaluable information onthe rotationactivity relation for the slow rotators, enabling tests of dynamotheory in a largely unconstrained regime. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]