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On steady force-free dynamos

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Abstract

It is shown that the amplification of the magnetic energy that results in steady force-free dynamos automatically implies a depletion of the overall mechanical and thermal energies of the fluid in the region. The precise gain and loss of the field and the fluid, respectively, are demonstrated. This offers a natural and direct explanation of the relative coolness of sunspots with respect to their surroundings and also predicts lower velocities over sunspot regions resulting from the smoothing of turbulent fluctuations of velocities by viscous stresses in the magnetic region. The missing energy of the fluid in the region is shown to reside in the increased magnetic energy of the sunspots.

It is also suggested that sunspots emerge from the photosphere in a manner analogous to the growth of salt fingers in thermohaline convection. Finally, it is pointed out that the growth and flaring process of solar magnetic fields can also be understood on the basis of the formalism presented.

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Authors and Affiliations

  1. Dept. of Physics, The University of Calgary, Alberta, Canada

    S. R. Sreenivasan

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  1. S. R. Sreenivasan
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Sreenivasan, S.R. On steady force-free dynamos. Astrophys Space Sci 51, 341–348 (1977). https://doi.org/10.1007/BF00644157

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  • DOI: https://doi.org/10.1007/BF00644157

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