ИСТИНА

SS 433 is a unique binary with moving emission lines in the spectrum. The moving components of Balmer and He I lines are formed by a pair of oppositely directed, highly collimated and precessing relativistic beams of very hot matter moving with a velocity of 0.26 c. The system is eclipsing with the period of 13.082 day. The 162-day precession period presents both in photometric and spectroscopic data. The star is located in the center of radio structure W50 interpreted as a 10000-year old supernova remnant. We have established the fact that the compact component in this system is a neutron star. The optical companion is an A4 I star (8.3-11.0 Msol) evolving to red giants. As a result of evolution, its expanding surface gradually moves closer to the orbit of the neutron star. Extensive 38-year photometric monitoring reveals secular changes of photometric behavior, expressed in reduction of the amplitude of orbital and precession variations, in episodic disappearance of eclipses, and increasing the duration of optically bright phases. We explain these phenomena with episodes of filling and overfilling the Roche lobe of the neutron star by the accreting gas from the companion, together with masking the system in a plain of the precessing and expanding circumbinary disk earlier described by Barnes et al., 2006. We foresee the future of SS 433 as a red giant with the neutron star inside.