The dependence of the dynamo alpha on vorticity
Open Access
- 21 June 1997
- journal article
- Published by Oxford University Press (OUP) in Monthly Notices of the Royal Astronomical Society
- Vol. 288 (2) , L29-L33
- https://doi.org/10.1093/mnras/288.2.l29
Abstract
We use data from numerical simulations of dynamo-generated turbulence in the shearing box approximation to determine the dynamo α-effect and its dependence on the rotation law Ω2(r). The data suggest that the dynamo α is not simply proportional to the local angular velocity Ω(r), as is usually assumed, but rather is proportional to the local vorticity ω(r) = r−1d/dr(ωr2 ). We also find tentative evidence to support the proposition that the backreaction of the magnetic field on α sets in when the field reaches equipartition with the energy in the turbulent motions. Furthermore, we propose an explanation as to why the sign of α is found to be opposite to that in the standard picture.Keywords
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