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Astron. Astrophys. 345, 1054-1058 (1999)

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Magnetic drift processes in differentially rotating turbulence

V. Urpin 1,2 and A. Brandenburg 1

1 Department of Mathematics, University of Newcastle, Newcastle upon Tyne, NE1 7RU, UK
2 A.F. Ioffe Institute of Physics and Technology, 194021 St. Petersburg, Russia

Received 27 August 1998 / Accepted 1 March 1999


The mean electromotive force is considered in a differentially rotating fluid taking into account stretching of the turbulent magnetic field. Calculations are performed by making use of the second order correlation approximation. Non-uniformity of the angular velocity leads to specific drift processes in the azimuthal direction. Due to this drift the magnetic field can rotate with a somewhat different angular velocity than the fluid. Differential rotation can also lead in a new instability of a non-axisymmetric mean field. Regardless of the law of the differential rotation this instability can result in an exponential amplification of the field.

Key words: accretion, accretion disks – Magnetohydrodynamics (MHD) – turbulence – stars: magnetic fields – ISM: magnetic fields

Send offprint requests to: V. Urpin

© European Southern Observatory (ESO) 1999

Online publication: April 28, 1999