NOAO >   Observing Info >   Approved Programs >   2014B-0120

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Proposal Information for 2014B-0120


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, Leibniz-Institute for Astrophysics Potsdam - AIP
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 (RV) survey, from which we have already identified a nearly complete sample of 329 solar-type (1.0 <=M [M_\odot] <=1.5) members in M37. Of these stars, 82 show significant RV variability, indicative of a binary companion. We propose to build upon these data with a multi-epoch RV survey using WIYN/Hydra to derive kinematic orbital solutions for these 82 binaries in M37. This project was first granted time in 2013B, and then again in 2014A, as an anticipated three-semester project. The aim of this project is to obtain at least ten RV measurements for each of these binaries, the minimum required to derive reliable kinematic orbital solutions. We anticipate reaching this goal for nearly all detected binaries with these proposed observations.


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