NOAO >   Observing Info >   Approved Programs >   2008A-0520

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Proposal Information for 2008A-0520


PI: Chip Kobulnicky, University of Wyoming, chipk@uwyo.edu
Address: Physics Department, 1000 E. University, Laramie, WY 82070, USA

CoI: Dan Kiminki, University of Wyoming

Title: Characterizing Massive Binaries in Cygnus OB2

Abstract: Close massive binary systems are the progenitors of energetic phenomena such as X-ray binaries and some classes of supernovae and (gamma)-ray bursts. Population synthesis models which predict the galactic and cosmic frequency of these events require reliable estimates of the \it mass ratio distribution and the \it orbital separation distribution among massive binaries. We used spectroscopic data on 150 OB stars in Cygnus OB2 from WIYN and 3 other observatories during 1999- 2007 to publish three papers constraining the mass ratio distribution and binary fraction for the ensemble and measuring orbital parameters (modulo inclination) for a growing number of newly discovered close massive binaries. We've also identified some ~50 massive stars that show significant radial velocity variations, probably due to multiplicity. Due to lack of short time baseline data (previous WIYN runs were largely lost to weather and fire), the periods for these systems cannot be presently constrained, so we are requesting 6 nights with WIYN/Hydra to provide short time-baseline coverage of these suspected short-period systems.


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NOAO >   Observing Info >   Approved Programs >   2008A-0520

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