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Physical properties of a polar coronal hole from 2 to 5 solar radiiObservations with a white-light coronagraph aboard Skylab are used to determine the boundaries of a coronal hole in the northern polar region and the three-dimensional density structure within the hole between heights of 2 and 5 solar radii. The boundary of the hole is found to be essentially axisymmetric about the polar axis, nearly radial from 3 to 6 solar radii, and located near 25 deg latitude at these heights. The radiances arising from the hole are interpreted as resulting from an axisymmetric density distribution whose logarithmic radial gradient is independent of position within the hole and whose magnitude increases with angular distance away from the hole's axis. The velocity distribution within the hole is obtained from the continuity equation by assuming that the particle flux flowing outward in the hole is similar to that measured for high-speed solar-wind streams at 1 AU, and it is shown that the transition from subsonic to supersonic flow occurs between 2.2 and 3 solar radii.
Document ID
19770049784
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Munro, R. H.
(High Altitude Observatory Boulder, Colo., United States)
Jackson, B. V.
(National Center for Atmospheric Research Boulder, CO, United States)
Date Acquired
August 8, 2013
Publication Date
May 1, 1977
Publication Information
Publication: Astrophysical Journal
Subject Category
Solar Physics
Accession Number
77A32636
Funding Number(s)
CONTRACT_GRANT: NAS5-3950
Distribution Limits
Public
Copyright
Other

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