[Normal Stars and WD -- Oral ]

## Collisionless plasmas in WR140, $\eta$~Carinae and other colliding-wind systems.

Andy Pollock, XMM-SOC European Space Agency
Michael F. Corcoran (USRA-CRESST/NASA-GSFC)

The several-year orbits of the most X-ray brilliant colliding-wind systems WR140 (WC7+O5) and $\eta$~Carinae (LBV) up to their nearly simultaneous periastron passages in 2009 January have given the opportunity to make direct high-resolution measurements of the collisionless plasma at different orbital phases. The clear differences are compared with the predictions of analytical and numerical models of the physics and dynamics involved. They also provide outstanding elemental abundance estimates for stellar evolutionary purposes and inform the shock physics at work in the binary systems in which the majority of massive stars are formed.