XMM OBSERVATIONS OF DH CEP AND UW CMA

We propose to observe DH Cep and UW CMa, two of the most massive Ostar binarysystems in our Galaxy. Both systems are expected to contain a highly radiativewindwind collision region, and are the ideal complement to the XMM AO1observations of Plaskett.s star (one wind radiative) and HD 159176 (neither windradiative), and to our proposal to observe V444 Cyg, a WolfRayet + Ostarsystem. As it appears likely that the windwind shock collapses onto the surfaceof the secondary star in UW CMa, DH Cep and UW CMa should have quite differentcolliding wind characteristics. DH Cep is also a member of the young opencluster NGC 7380, and we will conduct a detailed investigation of its populationof Xray sources. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]