Beam models for SS 433

Observational constraints on the energetics of beam models of the emission line object SS 433 are examined, and a likely astrophysical model is derived. Consideration is given to the main spectral features of the object, which exhibits red- and blue-shifted emission line systems which oscillate across the spectrum with large amplitudes, and the constraints these features impose on the two collimated gaseous streams emerging in opposite directions from a central object and precessing with a period of 164 days thought to be responsible for the shifted lines are discussed. Specific models for the excitation of the line-emitting gas are examined, and it is shown that excitation by shock-produced X-rays and EUV can account for most of the general features of the SS 433 spectrum. The action of the beams is discussed as the source of the supernovae remnant-like radio source W 50, on which SS 433 is centered. It is suggested that SS 433 contains a neutron star, and that the 164-day period and the geometry of the oscillations in beam direction can be explained by the geodetic precession of the rapidly rotating neutron star by a binary companion. Finally, the evolution of the system is discussed, and predictions of the model concerning the source spectrum and beam resolution are summarized.