NOAO >   Observing Info >   Approved Programs >   2010B-0492

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Proposal Information for 2010B-0492


PI: Soren Meibom, Harvard-Smithsonian Center for Astrophysics, smeibom@cfa.harvard.edu
Address: Optical and Infrared Astronomy Division, 60 Garden Street, Cambridge, MA 02138, USA

CoI: Sydney Barnes, Lowell Observatory
CoI: Aaron Geller, University of Wisconsin - Madison
CoI: Robert D. Mathieu, University of Wisconsin - Madison

Title: The connections between binarity, circumstellar disks, and stellar rotation

Abstract: We propose to study the effect on stellar rotation of binary companions within the typical circumstellar disk radius (\la 100 AU), but beyond the reach of tidal interactions (\ga 0.2 AU). A first hint of faster rotation among binary primary stars than among single stars has been detected in the ~150 Myr open cluster M35 (\it tidally synchronized binaries excluded). This result is consistent with a model scenario involving truncation of the mass, size, and lifetime of the circumstellar disk by a companion, and consequently a shortened phase of magnetic disk-braking of the stellar rotation during the PMS phase. The scenario suggests the hypothesis that a difference in rotation between single and binary primary stars should be more pronounced in younger stellar populations, and gradually disappear over time as magnetic winds spin down stars not tidally locked. We propose to test this hypothesis and test/strengthen the relation found in M35, by conducting a multi-epoch radial-velocity survey for membership and binarity in the rich open clusters NGC 2516 (~150 Myr) and NGC 3532 (~300 Myr), in concert with a comprehensive time-series photometric survey for rotation among late-type cluster members.


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