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Published online by Cambridge University Press: 07 August 2017
Although we now know of quite a few WR-O star binary systems, only HD 193793 is well studied across the entire electromagnetic spectrum. Hence it affords us the best opportunity to test various models for the system against a wealth of observational data. In this paper we present the results of 8 years of monitoring the radio flux density from HD 193793 with the VLA. This database is unique both in terms of its dense coverage of an entire binary cycle and because it extends the radio coverage to 2 cm wavelength, a shorter wavelength than previously available. With this data we are able to simultaneously solve for the time dependent attenuation in the system and the intrinsic radio luminosity. The standard model of spherically symmetric colliding winds faces severe difficulties in explaining the observations. We conclude that the radio data are most readily interpreted in the context of a WR star wind which is confined to a disk. A disk model for the WR wind also provides a natural explanation for the sudden formation of dust just after periastron.