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Plasma diagnostics for the outer solar corona - UV and XUV Fe XII linesThe formation of the UV and XUV spectral lines of Fe XII in the outer corona was investigated. The results indicate that these lines can be an important tool for probing the physical conditions in the coronal regions where the solar wind is generated. The Fe XII lines can be particularly useful for determining outflow velocities of heavy ions in the solar wind and for providing critical empirical constraints on energy transport and dissipation mechanisms in the solar wind acceleration region. Application of the theoretical calculations to existing UV, EUV, and XUV observations of the low corona provide evidence that: (1) the inclusion of the effects of resonances in the collision strengths for the low-lying levels of Fe XII is important, (2) that the contributions of resonances for these levels are even larger than the estimates given in the present paper, and (3) that the collision strengths used here yield populations for these levels which are accurate to a factor of 2. These results have implications concerning the accuracy of abundances and densities derived from observations of the Fe XII lines in the low corona.
Document ID
19850031713
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Withbroe, G. L.
(Harvard-Smithsonian Center for Astrophysics Cambridge, MA, United States)
Raymond, J. C.
(Harvard-Smithsonian Center for Astrophysics Cambridge, MA, United States)
Date Acquired
August 12, 2013
Publication Date
October 1, 1984
Publication Information
Publication: Astrophysical Journal, Part 1
Volume: 285
ISSN: 0004-637X
Subject Category
Solar Physics
Accession Number
85A13864
Funding Number(s)
CONTRACT_GRANT: NAGW-249
Distribution Limits
Public
Copyright
Other

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