Monday, Jan 10, 2011, 9:00 AM - 6:30 PM
The Columbia/Cornell/Caltech Palomar Transient Factory (CCCP) Praesepe Campaign: Studying the Rotation-Activity Relation in an Intermediate Age Cluster
Kevin R. Covey
, J. Lemonias
, M. Agueros
, N. Law
, A. Kraus
, K. Hamren
University of Toronto,
University of Hawaii, Monoa.
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 M
. 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.
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