HR: 1340h
AN: GP33A-0933    [Abstracts]
TI: Local and Global study of the MRI With Application to the Earth's Core
AU: * Petitdemange, L
EM: ludovic@lra.ens.fr
AF: Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique, Equipe MAG, Ecole Normale Supérieure, Département de Physique, LRA, 24 rue Lhomond, Paris, 75005, France
AU: Dormy, E
EM: dormy@ipgp.jussieu.fr
AF: Institut de Physique du Globe de Paris, Equipe MAG, Ecole Normale Supérieure, Département de Physique, LRA, 24 rue Lhomond, Paris, 75005, France
AU: Balbus, S
EM: steven.balbus@lra.ens.fr
AF: Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique, Equipe MAG, Ecole Normale Supérieure, Département de Physique, LRA, 24 rue Lhomond, Paris, 75005, France
AB: We investigate the magnetorotational instability (MRI) in a geophysical context. The MRI is known to play a crucial role in the stucture and evolution of astrophysical disks. It may also influence the radiative zone of stars, and possibly the generation of magnetic field in planetary cores. In order to study a possible connection with dynamo action in the Earth's core, we have carried out a WKB analysis of the MRI using a resistivity, magnetic field, and local rotation profile taken from standard models. Unstable modes are present with characteristic growth times of 1000 years. The calculation is compared against a global numerical model of spherical, magnetized Couette flow, and good agreement is found. The role of the MRI in the geophysical dynamo is secondary to thermal convection, though it may be important for regulating angular momentum transport.
DE: 1510 Dynamo: theories and simulations
DE: 5734 Magnetic fields and magnetism
DE: 7524 Magnetic fields
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2007 Fall Meeting