Hydromagnetic Stability of Thin Self-Gravitating Disks and Spiral Structure

Abstract

The hydromagnetio stability of infinitesimally thin, ourrent-oarrying, differentially rotating disks is oonsidered. The perturbation theory desoribed is first order (linear) throughout. It is shown that azimuthal eleotrio ourrent produoes instability for all (radial) wavelengths. The oase of radial equilibrium eleotrio ourrent reduoes to the non-hydromagnetio problem treated by Lin and Shu (1964), although hydromagnetio effeots are expeoted for a. disk of finite thiokness or to second order due to azimuthal perturbation ourrent.