We have detected new components in stationary emission lines of SS 433 ; these are the superbroad components that are low-contrast substrates with a width of 2000–2500 km \mbox { s } ^ { -1 } in He I \lambda 4922 and H \beta and 4000–5000 km \mbox { s } ^ { -1 } in He II \lambda 4686 .
Based on 44 spectra taken during four years of observations from 2003 to 2007 , we have found that these components in the He II and He I lines are eclipsed by the donor star ; their behavior with precessional and orbital phases is regular and similar to the behavior of the optical brightness of SS 433 .
The same component in H \beta shows neither eclipses nor precessional variability .
We conclude that the superbroad components in the helium and hydrogen lines are different in origin .
Electron scattering is shown to reproduce well the superbroad component of H \beta at a gas temperature of 20–35 kK and an optical depth for Thomson scattering \tau \approx 0.25–0.35 .
The superbroad components of the helium lines are probably formed in the wind from the supercritical accretion disk .
We have computed a wind model based on the concept of Shakura-Sunyaev supercritical disk accretion .
The main patterns of the He II line profiles are well reproduced in this model : not only the appearance of the superbroad component but also the evolution of the central two-component part of the profile of this line during its eclipse by the donor star can be explained .