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Faculae and east-west asymmetry of sunspot area.Asymmetry of sunspot area with respect to the central meridian is found to depend strongly on the location of the spot group in its chromospheric facula or plage. The usual area excess for spots in the eastern half of the disk is reversed for the relatively rare spot groups situated in the following part of the plage. Qualitatively, the observed asymmetries can be explained by supposing that the apparent area of the spot is decreased by overlying bright facula, especially west of central meridian where the spot (in the usual preceding position) is viewed through the relatively bright and extensive follower part of the plage. Since both facula and spot effects are seen along the same line of sight, optical depth must change slowly with geometric depth, that is, in the active region the atmosphere is relatively transparent.
Document ID
19720049121
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Sawyer, C.
Haurwitz, M. W.
(NOAA, Environmental Research Laboratories, Boulder Colo., United States)
Date Acquired
August 6, 2013
Publication Date
April 1, 1972
Publication Information
Publication: Solar Physics
Volume: 23
Subject Category
Space Sciences
Accession Number
72A32787
Funding Number(s)
CONTRACT_GRANT: NASA ORDER H-42710-A
Distribution Limits
Public
Copyright
Other

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