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The effect of an interaction of magnetic flux and supergranulation on the decay of magnetic plagesThis paper studies how the properties of large-scale convection affect the decay of plages. The plage decay, caused by the random-walk dispersion of flux tubes, is suggested to be severely affected by differences between the mean size of cellular openings within and around plages. The smaller cell size within a plage largely explains the smaller diffusion coefficient within plages as compared to that of the surrounding regions. The semipermeability of the plage periphery, together with the dependence of the diffusion coefficient on the flux-tube density, can explain the observed slow decay of plages (predicting a typical life time of about a month for a medium-sized plage), the existence of a well-defined plage periphery, and the observed characteristic mean magnetic flux density of about 100 G. One effect of the slowed decay of the plage by the semipermeability of the plage periphery is the increase of the fraction of the magnetic flux that can cancel with flux of the opposite polarity along the neutral line to as much as 80 percent as compared to at most 50 percent in the case of nonuniform diffusion. This may explain why only a small fraction of the magnetic flux is observed to escape from the plage into the surrounding network.
Document ID
19900063259
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Schrijver, C. J.
(Joint Institute for Laboratory Astrophysics Boulder, CO, United States)
Date Acquired
August 14, 2013
Publication Date
January 1, 1989
Publication Information
Publication: Solar Physics
Volume: 122
Issue: 2 19
ISSN: 0038-0938
Subject Category
Solar Physics
Accession Number
90A50314
Funding Number(s)
CONTRACT_GRANT: NGL-06-003-057
Distribution Limits
Public
Copyright
Other

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