2008/02/03 by Jesse Pino, S. M. Mahajan, S. M. Mahajan · 1 citation
Physics and Astronomy · #Astrophysics and Star Formation Studies #Dust and Plasma Wave Phenomena #Solar and Space Plasma Dynamics #astro-ph
paper · pdf · doi:10.1086/586705
published as ApJ 678:1223, 2008 May 10 · 22 pages, 5 figures
arxiv created 2008/02/03 · openalex publication_date 2008/04/30 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/31
We examine global incompressible axisymmetric perturbations of a differentially rotating MHD plasma with radial density gradients. It is shown that the standard magnetorotational instability (MRI) criterion drawn from the local dispersion relation is often misleading. If the equilibrium magnetic field is either purely axial or purely toroidal, the problem reduces to finding the global radial eigenvalues of an effective potential. The standard Keplerian profile including the origin is mathematically ill-posed, and thus any solution will depend strongly on the inner boundary. We find a class of unstable modes localized by the form of the rotation and density profiles, with reduced dependence on boundary conditions.