A geometrical model for the SS 433 system

A geometrical model is suggested for the SS 433 stellar system, consisting of a compact object and a star revolving around each other. The system includes a processing accretion disc around the compact object and a hotspot on the disc surface. With these elements, most of the photometric characteristics of the system described in Leibowitz et al. can be accounted for, as well as a few other observations of this star. The parameters of the model adjusted by a least squares procedure yield a mass ratio in the system $$m(\text {compact})/M_\star \geqslant 0.8$$. Combined with results of radial velocity measurements by Crampton & Hutchings, the model parameters imply that the compact object is probably a black hole of 10–100 solar masses, the star is an early B, an O or a super-massive star. The average accretion rate in the system is $$\gt 2.5 \times 10^{-4} M_\odot/\text {yr}$$. Two possible physical interpretations of the model are proposed and a few predictions are made for additional tests of the model against future observations.