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A statistical study of high coronal densities from X-ray line-ratios of Mg XIAn X-ray line-ratio density diagnostic was applied to 50 Mg XI spectra of flaring active regions on the sun recorded by the Flat Crystal Spectrometer on the SMM. The plasma density is derived from R, the flux ratio of the forbidden to intercombination lines of the He-like ion, Mg XI. The R ratio for Mg XI is only density sensitive when the electron density exceeds a critical value (about 10 to the 12th/cu cm), the low-density limit (LDL). This theoretical value of the low-density limit is uncertain as it depends on complex atomic theory. Reported coronal densities above 10 to the 12th/cu cm are uncommon. In this study, the distribution of R ratio values about the LDL is estimated and the empirical values are derived for the 1st and 2nd moments of this distribution from 50 Mg XI spectra. From these derived parameters, the percentage of observations is derived which indicated densities above this limit.
Document ID
19910044899
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Linford, G. A.
(Lockheed Missiles and Space Co. Palo Alto, CA, United States)
Lemen, J. R.
(Lockheed Missiles and Space Co. Palo Alto, CA, United States)
Strong, K. T.
(Lockheed Research Laboratories Palo Alto, CA, United States)
Date Acquired
August 14, 2013
Publication Date
January 1, 1991
Publication Information
Publication: Advances in Space Research
Volume: 11
Issue: 1 19
ISSN: 0273-1177
Subject Category
Solar Physics
Accession Number
91A29522
Funding Number(s)
CONTRACT_GRANT: NAS5-30431
Distribution Limits
Public
Copyright
Other

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