The disk-driven precession model, proposed originally for SS 433 by Sarazin et al. (1980), is applied to extragalactic radio jets. Byeresenting a statistical relationship between the precession period and optical luminosity fo the sources, it is shown that the observational evidence is in favor of the model.

We clarify the concept of Keplerian circular motion of fluidsin the theory of general relativity, showing how it overlaps with as well as differs from the counterpart in the particle case. Applying the concept to the study of accretion disks, we prove a constraint on the sonic transition of accretion flows.

Transonic motion of adiabatic jets from funnels of thick accretion disks around Kerr black holes is studied. Provided the matter at the bottom of the funnel possesses a high enough enthalpy, the location of the sonic point of the flow can be very close to its lower limit, and an extremely relativistic terminal velocity can be achieved.

Received September 10, 1984; accepted February 12, 1985 Summary. The fact that the adiabatic transonic accretion of rotating matter onto a black hole has non-unique, bimodal, solution was demonstrated previously only in terms of an approximate, Newtonian, model. Here the correct generalrelativistic equations are used to prove the bimodal character of accretion onto a Schwarzschild black hole.

This paper presents global solutions of adiabatic accretion flows with isothermal shocks in the potential of a non-rotating black hole. It is known that in the previously studied cases, where flow including shock is either entirely adiabatic or entirely isothermal, there can be no more than one stable shock solution, and the solution can only be of the a-x type; however, the solution topology in the present case shows new remarkable characteristics: for the same flow parameters there can be two stable shock solutions satisfying the physical boundary conditions, and the solution can be of three types, namely a-x, x-a, and a-a type. In addition, shocks in the present case occur for a parameter region that is different from that for RankineHugoniot shocks to occur. These results greatly increase the possibilities of shock formation in astrophysical flows. It is also noted that in the present case the efficiency of energy release at the shock can be as high as a few percent. Finally, a brief comparison is made between shocked inviscid flows and two types of shock-free viscous flow, namely that of Shakura and Sunyaev (1973, AAA 09.066.049) and that of Narayan and Yi (1994, AAA 61.064.083).