2007ApJ...660L.141P

Clumping in hot star winds can significantly affect estimates of mass-loss rates, the inferred evolution of the star, and the environmental impact of the wind. A hydrodynamical simulation of a colliding winds binary (CWB) with clumpy winds reveals that the clumps are rapidly destroyed after passing through the confining shocks of the wind-wind collision region (WCR) for reasonable parameters of the clumps if the flow in the WCR is adiabatic. Despite large density and temperature fluctuations in the postshock gas, the overall effect of the interaction is to smooth the existing structure in the winds. Averaged over the entire interaction region, the resulting X-ray emission is very similar to that from the collision of smooth winds. The insensitivity of the X-ray emission to clumping suggests it is an excellent diagnostic of the stellar mass-loss rates (M{dot}) in wide CWBs and may prove to be a useful addition to existing techniques for deriving M{dot}, many of which are extremely sensitive to clumping. Clumpy winds also have implications for a variety of phenomena at the WCR: particle acceleration may occur throughout the WCR due to supersonic MHD turbulence, reacceleration at multiple shocks, and reconnection; a statistical description of the properties of the WCR may be required for studies of nonequilibrium ionization and the rate of electron heating; and the physical mixing of the two winds will be enhanced, as seems necessary to trigger dust formation.