Constraints on the physical properties of optical bullets in SS 433

The present study discusses possible mechanisms for continuously heating the H-alpha emitting bullets of SS 433 out to distances of 5 x 10 to the 14th cm and for turning off this emission at 10 to the 15th. Various observational contraints are used to establish bounds on permissible solutions in terms of the two key bullet parameters, mass, and angular radius seen from the central source. The analysis is carried out for the mathematically simplest case of uniform spherical bullets. For radiative heat of such bullets by starlight, solutions are found to exist only for the very massive bullets with about 0.03 radians, which are highly implausible on the grounds of the large implied mean kinetic luminosity of about 10 to the 41st ergs/s. It is concluded that collisional interaction is the most likely mechanism for heating the optical bullets of SS 433. The effects of these constraints being fragmented rather than uniform, and being elongated rather than spherical are discussed.