BibTeX
@MISC{Ossendrijver00thedynamo,
author = {M.A.J.H. Ossendrijver},
title = {The Dynamo Effect of Magnetic Flux Tubes},
year = {2000}
}
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Abstract
. It is shown that toroidal magnetic ux tubes in a rotating star do not provide a net dynamo eect, even if they are subject to random forcing, unless the tubes are unstable to small displacements. The dynamo eect is produced by transverse helical waves that propagate along the ux tube, resulting in an electric current (anti-) parallel to the unperturbed magnetic eld, equivalent to an alpha eect. For unstable ux tubes, the alpha eect is enabled by a systematic phase dierence between the velocity and magnetic eld perturbations. For stable ux tubes subject to random forcing, phase dierences do occur, but they vanish in the mean. The requirement for instability is met if the magnetic eld strength exceeds a threshold value. Therefore a stellar dynamo based on ux tubes is not self-excited, but needs triggering until the magnetic threshold is surpassed. Key words: MHD { stars: magnetic elds { stars: latetype { Sun: magnetic elds 1. Introduction A key issue of stellar dynamo...
Keyphrases
dynamo effect magnetic flux tube alpha eect ux tube stellar dynamo unperturbed magnetic eld phase dierences net dynamo eect threshold value magnetic eld toroidal magnetic ux tube small displacement latetype sun unstable ux tube magnetic eld star mhd star key issue stable ux tube dynamo eect magnetic eld perturbation magnetic eld strength rotating star transverse helical wave magnetic threshold key word systematic phase dierence
