Name/Affiliation: David Jaimes (Department of Astronomy, Columbia University)
Anchoring the age-rotation relation with the ZAMS cluster Alpha Per
Calibrating the age-rotation-activity relation (ARAR) in low-mass stars requires systematically mapping out the properties of stars in coeval populations. The Palomar Transient Factory (PTF) Open Cluster Survey (POCS) is an effort to measure rotation periods and coronal or chromospheric tracers of magnetic activity for stars in clusters ranging from 80 Myr and 2.5 Gyr. We present preliminary POCS results for Alpha Per (Mel 20), the youngest survey target. Late-type stars in this cluster are arriving on the zero-age main sequence (ZAMS), and provide an essential anchor point for modeling the ARAR. We revisit the clusterís membership, and construct a revised catalog that considers a starís distance from the cluster center in addition to photometric and proper-motion data from a number of surveys. In addition, we present on-going efforts to use our PTF data from roughly eight months of optical monitoring to expand the sample of measured rotation periods for Alpha Per members. Only ~40 rotation periods have been measured in Alpha Per to date, limiting the clusterís utility as a benchmark for the early stage ARAR. With an updated membership catalog and new rotation periods measured with PTF, Alpha Per will provide critical data for defining the ZAMS-era ARAR.