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   PR # 22029
    Gamma Vel is a central object for the emerging field of colliding-   
    winds. Our 13 ROSAT observations over several cycles of the 78 day bi
    nary period showed at most phases that the X-ray emission is constant
    (kT=0.2keV, Lx=3E31erg/s), but near phase 0.5 (O-star in front) the  
    X-ray emission increases by 4x, due to an additional hard component w
    kT>2keV. This is phase repeatable and due to emission from the wind  
    collision seen through a cavity in the WR wind caused by the O-star. 
    Our hydro models predict X-ray emission at kT=3-10keV, consistent w/,
    but not constrained by the ROSAT data. We propose ASCA observations  
    of Gamma Vel at phases around 0.5, to provide obs of the harder com- 
    ponent, yielding measurements of its spectrum, Lx and NH required to 
   test colliding wind theor     
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