Presentation Abstract

Presentation Number 153.06
Presentation Time: Monday, Jan 10, 2011, 9:00 AM - 6:30 PM
Title The Columbia/Cornell/Caltech Palomar Transient Factory (CCCP) Praesepe Campaign: Studying the Rotation-Activity Relation in an Intermediate Age Cluster
Author Block Kevin R. Covey1, J. Lemonias2, M. Agueros2, N. Law3, A. Kraus4, K. Hamren1
1Cornell University, 2Columbia University, 3University of Toronto, 4University of Hawaii, Monoa.
Abstract For several decades, observational surveys have demonstrated a closerelationship between a star’s rotation period, magnetic activity, and age. The age-activity-rotation relation is well documented in clusters younger than 500 Myrs, but its subsequent evolution is less clear. Using wide-field, multi-epoch photometry from the Palomar Transient Factory, we have monitored ~530 members of the Praesepe open cluster, a ~600 Myr nearby Hyades analog. With light curves containing >150 measurements over more than three months, we have measured rotation periods for ~50 K & M-type cluster members. These rotation periods span the gap between the periods measured for solar-type Hyads and the lowest-mass Praesepe members, and indicate that the orderly mass-rotation relation seen for higher mass Praesepe members begins to break down at ~0.6 Msun. Below this critical mass, a range of rotation periods spanning an order of magnitude are observed for stars with similar masses. Combining these rotation measurements with archival X-ray and Halpha observations completes the portrait of the ~600 Myr age-activity-rotation relation, and enables a detailed comparison with Praesepe's sister cluster, the Hyades.