NOAO >   Observing Info >   Approved Programs >   2013B-0039

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Proposal Information for 2013B-0039


PI: Aaron M. Geller, Northwestern University, a-geller@northwestern.edu
Address: CIERA and Dept. of Physics & Astronomy, 2131 Tech Drive, Evanston, IL 60208, USA

CoI: Soren meibom, Harvard-Smithsonian Center for Astrophysics
CoI: Sydney A. Barnes, Space Science Institute
CoI: Robert D. Mathieu, University of Wisconsin - Madison

Title: The Solar-Type Hard-Binary Frequency and Distributions of Orbital Parameters in the Open Cluster M37

Abstract: Binary stars, and particularly the short-period ``hard'' binaries, govern the dynamical evolution of star clusters and determine the formation rates and mechanisms for exotic stars like blue stragglers and X-ray sources. Understanding the near-primordial hard-binary population of star clusters is of primary importance for dynamical models of star clusters, which have the potential to greatly advance our understanding of star cluster evolution. Yet the binary frequencies and distributions of binary orbital parameters (period, eccentricity, etc.) for young coeval stellar populations are poorly known, due to a lack of necessary observations. The young (~540 Myr) open cluster M37 hosts a rich binary population that can be used to empirically define these initial conditions. Importantly, this cluster has been the target of a comprehensive WIYN/Hydra radial-velocity survey, from which we have already identified a nearly complete sample of 329 solar-type (1.5 <=M [M_\odot] <=1.0) members in M37. Of these stars, 82 show significant radial-velocity variability, indicative of a binary companion. We propose to build upon these data with a multi-epoch radial-velocity survey using WIYN/Hydra to derive kinematic orbital solutions for these 82 binaries in M37. These data will provide the empirical frequency distributions of periods, eccentricities, etc., that are necessary to define initial conditions for dynamical star cluster models.


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