X-ray Observations of the Jets in SS 433

EXOSAT observations of SS433 have revealed the presence of an emission line whose energy varies with time. The variation is consistent with that predicted for a line with a rest energy of 6.7 keV with shifts in energy analogous to those of the moving optical emission lines, i.e. the material emitting the X-rays is in jets moving at 0.26 c and precessing about a fixed axis. Constraints are derived on the dimensions of the components of the SS433 system. In conjunction with previously derived optical results this leads to a mass estimate for the compact object in the system of >10 M_sun;. The energetics of the material responsible for the X-ray emission from the jet also require a mass of >10 M_sun; if the system is to be sub-Eddington.