Abstract
It is shown that horizontal radial flow in the penumbra is not inconsistent with a vertical component of the penumbral magnetic field. The magnetic amplification produced by the stretching of the magnetic-flux tubes in this velocity field yields a resultant field whose typical inclination to the horizontal is about 20°. It is shown that the thermal convection forces can balance the magnetic forces restraining this flow and that the magnetic energy produced by the stretching of the flux tubes is of the same order of magnitude as the sunspot-energy deficit. Finally, a mechanism is suggested for dispersing this magnetic energy over a large region of the solar surface.
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On leave from the University of Sydney.
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Wilson, P.R. The structure of a sunspot. Sol Phys 3, 454–465 (1968). https://doi.org/10.1007/BF00171619
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DOI: https://doi.org/10.1007/BF00171619