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L. E. Simon (Macalester College / University of Wyoming), H. A. Kobulnicky (University of Wyoming)
The distribution of the mass ratios in binary star systems, especially among massive O and B type stars, is currently not well known. Better observational constraints on this distribution are needed in order to reconcile our conception of massive binary star formation and the frequency of their energetic descendants such as X-ray binaries, supernovae, and gamma-ray bursts. Massive binaries are more likely to become high-energy phenomenon such as X-ray binaries because of their small orbital separation. We present a preliminary report on an observational program intended to measure the frequency of companions and the initial mass ratio distribution among massive stars. We are conducting photometric monitoring of 146 early type stars in the Cygnus OB2 association to find the population of eclipsing systems. This survey, begun in June 2003 and using the UW Red Buttes 0.6m telescope, is currently sensitive to fairly short period binaries with periods of about one year. As binary systems are discovered, we will combine the photometric data with ongoing radial velocity data to determine distributions of stellar mass ratios and orbital separations. These data from Cyg OB2 can then be used to infer the general distribution of mass ratios in massive binary systems in the Galaxy and beyond. This work has been supported by NSF REU site grant AST 0097356.
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Bulletin of the American Astronomical Society, 35#5
© 2003. The American Astronomical Soceity.