Membership, Rotation, Activity, and Lithium Abundances in a Selection of Nearby Clusters

University Of California-Santa Cruz, Santa Cruz CA

Investigators

Abstract

AST 0307585 Jones, Burton F. This project will expand our knowledge of how stars like the Sun evolve by obtaining membership information for stars in nearby star clusters. Observations of star clusters have long provided the best link to theories of stellar structure and evolution. Stellar models of a given mass, composition, and age predict luminosity and effective temperature (color). Under the reasonable assumption that all stars in a cluster are the same age and chemical composition, cluster color versus magnitude diagrams provide templates against which the luminosity and effective temperature of stellar models can be compared. Lick Observatory has a collection of first epoch glass plate negatives of open star clusters taken around 1970 with the 36 inch refractor. Over the last three years second epoch plates of 11 nearby clusters were taken. The second epoch photography of these clusters, and 4 more clusters, is being completed. Suitable plate measurements are then used to determine proper motions for stars in the clusters and thence membership probability estimates for individual stars. Spectroscopic observations will be obtained of member stars in several of the clusters for the determination of abundances, stellar activity, and rotation. This database will be used by the PI and others toward a better understanding of the evolution of stellar activity, lithium abundance, and rotation in solar type stars different ages and metallicities. Broader Impacts. This research will produce a database with importance for studies of the mass and luminosity functions and the dynamical evolution of open star clusters, and will also be of use to spectroscopic observers who want to observe cluster members at high dispersion. This database will be made freely available. This grant supports collaboration with astronomers in Germany and at the Space Telescope Science Institute.