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Development of structure in pores and sunspots: flows around axisymmetric magnetic flux tubes

Hurlburt, N.E. and Rucklidge, A.M. (2000) Development of structure in pores and sunspots: flows around axisymmetric magnetic flux tubes. Monthly Notices of the Royal Astronomical Society, 314 (4). pp. 793-806. ISSN 0035-8711

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Flux elements, pores and sunspots form a family of magnetic features observed at the solar surface. As a first step towards developing a fully nonlinear model of the structure of these features and of the dynamics of their interaction with solar convection, we conduct numerical experiments on idealised axisymmetric flux tubes in a compressible convecting atmosphere in cylindrical boxes of radius up to eight times their depth. We find that the magnetic field strength of the flux tubes is roughly independent of both distance from the centre and the total flux content of the flux tube, but that the angle of inclination from the vertical of the field at the edge of the tube increases with flux content. In all our calculations, fluid motion converges on the flux tube at the surface. The results compare favourably with observations of pores; in contrast, large sunspots lie at the centre of an out-flowing moat cell. We conjecture that there is an inflow hidden beneath the penumbrae of large spots, and that this inflow is responsible for the remarkable longevity of such features.

Item Type: Article
Copyright, Publisher and Additional Information: Copyright © 2000 Royal Astronomical Society. This is an author produced version of an article published in Monthly Notices of the Royal Astronomical Society. This paper has been peer-reviewed but does not include the final publisher proof-corrections or journal pagination.The definitive version is available at www.blackwell-synergy.com.
Keywords: convection, MHD, sun, interior, magnetic fields, sunspots
Institution: The University of Leeds
Academic Units: The University of Leeds > Faculty of Maths and Physical Sciences (Leeds) > School of Mathematics (Leeds) > Applied Mathematics (Leeds)
Depositing User: A. M. Rucklidge
Date Deposited: 10 Feb 2006
Last Modified: 09 Jun 2014 23:09
Published Version: http://www.blackwell-synergy.com/doi/abs/10.1046/j...
Status: Published
Refereed: Yes
Identification Number: 10.1046/j.1365-8711.2000.03407.x
URI: http://eprints.whiterose.ac.uk/id/eprint/988

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