Binary Stars in Open Clusters: Connecting Observations and Simulations

Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA) and Department of Physics and Astronomy, Northwestern University, 2145 Sheridan Rd, Evan-ston, IL 60208, USA

Abstract

Open clusters are laboratories for testing theories of binary evolution and dynamics against detailed observations. As part of the WIYN Open Cluster Study (WOCS), we are currently observing several open clusters spanning a wide range in age and metallicity, with primary goals of determining the binary frequencies and distributions of binary orbital parameters for their solar-type stars. Currently, the three WOCS clusters with the most complete data sets are M35 (0.15 Gyr), M67 (4 Gyr) and NGC 188 (7 Gyr). Despite the large differences in age, we find that all three of these rich clusters have remarkably similar solar-type binaries that are also consistent with comparable binaries in the Galactic field. These data have been critical for guiding our sophisticated open cluster N-body simulations, which enable us to investigate the dynamical evolution of rich binary populations and the production of exotic stars, like blue stragglers, within open clusters.