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Solar and Astrophysical Magnetohydrodynamic Flows pp 1–16Cite as

Questions and Conjectures on the Origin of Stellar and Galactic Magnetic Fields

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Part of the book series: NATO ASI Series ((ASIC,volume 481))

Abstract

The magnetic fields of the Sun and the Galaxy, as prototypes of the fields of other stars and galaxies, appear to originate in some form or variant of the well known αω-dynamo. However, the αω-dynamo can function only in the presence of irreversible diffusion and dissipation of the small-scale internal magnetic fields. requiring effective diffusion coefficients of the order of 1012 and 1025 cm2/sec for the Sun and Galaxy, respectively. The internal motions of scale l and velocity v provide the product lv with these magnitudes, but the effect is not one of irreversible diffusion. So the αω-dynamo does not work in the manner conventionally associated with turbulent diffusion. It is hypothesized instead that the magnetic field of the Sun is in an intensely fibril state throughout the convective zone, with rapid reconnection wherever nonparallel fibrils are pressed together by the fluid motions. The result of this scenario would seem to be a sufficiently rapid irreversible interdiffusion of fields for successful operation of the solar dynamo. For the Galaxy it is hypothesized that rapid reconnection between the extended magnetic lobes or Ω-loops that form the halo accomplished the irreversibility necessary for the operation of the galactic dynamo. However, it must be emphasized that until these conjectures are firmly established, it cannot be said that we understand the origin of the magnetic fields of stars and galaxies. The fact that there is at present no known alternative to the αω-dynamo is not to say that the αω-dynamo operation is fully understood.

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  1. Enrico Fermi Institute and Depts. of Physics and Astronomy, The University of Chicago, 933 East 56th Street, 60637, Chicago, Illinois, USA

    Eugene Parker

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  1. Department of Physics, University of Crete, Heraklion, Greece

    Kanaris C. Tsinganos

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Parker, E. (1996). Questions and Conjectures on the Origin of Stellar and Galactic Magnetic Fields. In: Tsinganos, K.C. (eds) Solar and Astrophysical Magnetohydrodynamic Flows. NATO ASI Series, vol 481. Springer, Dordrecht. https://doi.org/10.1007/978-94-009-0265-7_1

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  • DOI: https://doi.org/10.1007/978-94-009-0265-7_1

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