Hydromagnetic Instability in Differentially Rotating Flows

Abstract

We study the stability of a compressible differentially rotating flows in the presence of the magnetic field, and we show that the compressibility profoundly alters the previous results for a magnetized incompressible flow. The necessary condition of newly found instability can be easily satisfied in various flows in laboratory and astrophysical conditions and reads $B_s{B}_{\varphi }{\Omega }^{\prime }\ne 0$ where $B_s$ and $B_{\varphi }$ are the radial and azimuthal components of the magnetic field, ${\Omega }^{\prime }=d\Omega /ds$ with $s$ being the cylindrical radius. Contrary to the well-known magnetorotational instability that occurs only if $\Omega$ decreases with $s$, the instability considered in this paper may occur at any sign of ${\Omega }^{\prime }$. The instability can operate even in a very strong magnetic field which entirely suppresses the standard magnetorotational instability. The growth time of instability can be as short as few rotation periods.

5 pages, 3 figures

Cited by in corpus (6)

• Experiments on the magnetorotational instability in helical magnetic fields
• Stability of magnetic configurations containing the toroidal and axial fields
• Stretching of the toroidal field and generation of magnetosonic waves in differentially rotating plasma
• Magnetic shear-driven instability and turbulent mixing in magnetized protostellar disks
• Magnetohydrodynamic instability in differentially rotating compressible flow
• Hydromagnetic Instability in plane Couette Flow