A Powerful Local Shear Instability in Weakly Magnetized Disks. I. Linear Analysis
Abstract
A broad class of astronomical accretion disks is presently shown to be dynamically unstable to axisymmetric disturbances in the presence of a weak magnetic field, an insight with consequently broad applicability to gaseous, differentiallyrotating systems. In the first part of this work, a linear analysis is presented of the instability, which is local and extremely powerful; the maximum growth rate, which is of the order of the angular rotation velocity, is independent of the strength of the magnetic field. Fluid motions associated with the instability directly generate both poloidal and toroidal field components. In the second part of this investigation, the scaling relation between the instability's wavenumber and the Alfven velocity is demonstrated, and the independence of the maximum growth rate from magnetic field strength is confirmed.
 Publication:

The Astrophysical Journal
 Pub Date:
 July 1991
 DOI:
 10.1086/170270
 Bibcode:
 1991ApJ...376..214B
 Keywords:

 Accretion Disks;
 Magnetohydrodynamic Stability;
 Stellar Magnetic Fields;
 Stellar Mass Accretion;
 Boussinesq Approximation;
 Computational Astrophysics;
 Linear Systems;
 Astrophysics;
 ACCRETION;
 HYDRODYNAMICS;
 HYDROMAGNETICS;
 INSTABILITIES