ON REGULATION OF THE JET SPEED IN SS-433

The speed of SS 433 jets has been observed to be temporally constant. It is proposed that this constancy is regulated by a pair creation processes in which the temperature reaches its maximum. When the energy input at the base of the jet increases, the additional energy is consumed so as to produce particles while the temperature maintains a maximum value. Thus, the jet speed, which is supposed to be attained by the conversion of thermal energy, does not change. If the jet emanates from the two-temperature pair atmosphere near 5r(g), the jet would have a terminal speed of 0.2c according to the hydrodynamical picture.