TOPOLOGICAL TRANSITION FROM ACCRETION TO EJECTION IN A DISK-JET SYSTEM—SINGULAR PERTURBATION OF THE HALL EFFECT IN A WEAKLY IONIZED PLASMA

A thin disk accompanied by spindle-like jet, created commonly near massive central objects, exhibits a topologically singular aspect when viewed from an ideal macroscopic theory. The accreting inflow and jet's outflow are singular perturbation on the ambient Keplerian rotation, which are generated by some nonideal higher order (in the order of derivatives) effects. The Hall effect can generate such a structure in a weakly ionized plasma of a protostellar disk. Numerical estimate of the characteristic length scale defined by the singular perturbation justifies the precedence of the Hall effect.