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A powerful local shear instability in weakly magnetized disks. III - Long-term evolution in a shearing sheet. IV - Nonaxisymmetric perturbationsThe nonlinear evolution of the recently identified accretion disk magnetic shear instability is investigated through a series of numerical simulations. Finite-difference computations of the equations of compressible MHD are carried out on an axisymmetric shearing sheet system with periodic boundary conditions designed to approximate a local region within an accretion disk. Initial field configurations that include some net vertical component evolve into a nonlinear, exponentially growing solution with large poloidal velocities and magnetic fields with energies comparable to the thermal energy density. The stability of a purely azimuthal field configuration is examined, and it is found that nonaxisymmetric instability is present, but with a growth time measured in tens of orbital periods. In general, the most rapid growth occurs for very small radial and azimuthal wavenumbers, leading to coherent magnetic field structure in planes parallel to the disk. It is suggested that this instability is a key ingredient for the generation of magnetic fields in disks.
Document ID
19930032446
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Hawley, John F.
(NASA Headquarters Washington, DC United States)
Balbus, Steven A.
(Virginia Univ. Charlottesville, United States)
Date Acquired
August 15, 2013
Publication Date
December 1, 1992
Publication Information
Publication: Astrophysical Journal, Part 1
Volume: 400
Issue: 2
ISSN: 0004-637X
Subject Category
Astrophysics
Accession Number
93A16443
Funding Number(s)
CONTRACT_GRANT: NAGW-1510
CONTRACT_GRANT: NAGW-2376
CONTRACT_GRANT: NSF AST-90-21348
CONTRACT_GRANT: NSF PHY-90-18251
Distribution Limits
Public
Copyright
Other

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