XMM observations of Plaskett.s Star and HD159176

We propose to gather XMM observations of two selected earlytype colliding winds binaries (Plaskett.s Star & HD159176). The resultant exposures will provide high quality EPIC and RGS spectra which will be used to constrain the mass loss rates of the stars, to investigate the effects of various hydrodynamical processes and to study the chemical abundances of the stellar winds. Furthermore, the EPIC observations will enable us, for the first time, to seek for the predicted dynamical instabilities of the wind interaction region which should lead to strong variability of the Xray flux on time scalesof 30 minutes. Our results should improve our understanding of the mass loss mechanism of massive stars and ultimately help to understand their truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]