086532

The X-ray spectrum of the colliding-wind binary WR140 at apastron is produced under benign conditions of minimum density and minimum orbital velocity and forms the initial plasma state from which subsequent evolution occurs. The star.s precise orbit comma exceptional X-ray brightness comma rich observational history and characteristic X-ray temperature very similar to that of the Perseus Cluster of Galaxies make it the ideal reference for calibration of models of plasmas produced under dynamical and thermodynamical conditions similar to those that hold in a variety of prominent X-ray sources. As well as precise tests of predicted photometry comma a joint RGS-HETG high-resolution spectrum will test a predicted emission-line redshift at apastron.