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Sunspots and the physics of magnetic flux tubes. I - The general nature of the sunspot. II - Aerodynamic dragAnalysis of the dynamical stability of a large flux tube suggests that the field of a sunspot must divide into many separate tubes within the first 1000 km below the surface. Buoyancy of the Wilson depression at the visible surface and probably also a downdraft beneath the sunspot hold the separate tubes in a loose cluster. Convective generation of Alfven waves, which are emitted preferentially downward, cools the tubes. Aerodynamic drag on a slender flux tube stretched vertically across a convective cell is also studied. Since the drag is approximately proportional to the local kinetic energy density, the density stratification weights the drag in favor of the upper layers. Horizontal motions concentrated in the bottom of the convective cell may reverse this density effect. A downdraft of about two km/sec through the flux tubes beneath the sunspot is hypothesized.
Document ID
19790055642
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Parker, E. N.
(Chicago, University Chicago, Ill., United States)
Date Acquired
August 9, 2013
Publication Date
June 15, 1979
Publication Information
Publication: Astrophysical Journal
Subject Category
Solar Physics
Accession Number
79A39655
Funding Number(s)
CONTRACT_GRANT: NGL-14-001-001
Distribution Limits
Public
Copyright
Other

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