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Relations between the photospheric magnetic field and the emission from the outer atmospheres of cool stars. I - The solar Ca II K line core emissionObservations of a solar active region complex and its surroundings are used to establish a quantitative relation between the Ca II K line core intensity and magnetic flux density. The Ca II K line core intensity is transformed to a Ca II H + K line core flux density to facilitate a comparison of solar and stellar data. A new absolute calibration for the Mount Wilson Ca II H + K fluxes for G-type dwarfs is derived. The minimum Ca II K flux, found in the centers of supergranulation cells in quiet regions on the sun, is identical to the minimum flux that is observed for solar-type stars. An expression is presented for the nonlinear trend between the Ca II H + K line core excess flux density and the absolute value of the magnetic flux density. Models that explain the nonlinearity of the mean trend and the large intrinsic scatter about it are discussed. The solar data define a relation that is similar to the relation between stellar hemisphere-average magnetic flux densities and Ca II H + K excess flux densities.
Document ID
19890042539
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)
Cote, J.
(SRON Laboratorium voor Ruimteonderzoek; Utrecht, Rijksuniversiteit, Netherlands)
Zwaan, C.
(Utrecht Rijksuniversiteit, Netherlands)
Saar, S. H.
(Joint Institute for Laboratory Astrophysics, Boulder, CO; Harvard-Smithsonian Center for Astrophysics, Cambridge MA, United States)
Date Acquired
August 14, 2013
Publication Date
February 15, 1989
Publication Information
Publication: Astrophysical Journal, Part 1
Volume: 337
ISSN: 0004-637X
Subject Category
Solar Physics
Accession Number
89A29910
Funding Number(s)
CONTRACT_GRANT: NGL-06-003-057
CONTRACT_GRANT: NAG5-82
Distribution Limits
Public
Copyright
Other

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