On the stability of wind accretion.

Results of numerical investigations of accretion flows past a compact object are reported. A strong tendency toward nonsteady flow is found to exist in both 2D and 3D computations. Steady flows are obtained only when the numerical resolution is low or the central absorbing body is large. It is concluded that: (1) accretion from a homogeneous medium onto a compact object is intrinsically nonsteady; (2) the instability manifests itself in 'flip-flop' oscillations of the accretion shock cone, accompanied by short phases of quasi-disk formation, with the sense of rotation reversing periodically; and (3) no density or velocity gradients in the incoming flow are required for the instability to develop.