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Measurements of transition probabilities for spin-changing lines of atomic ions used in diagnostics of astrophysical plasmasThe intensities of ultraviolet, spin-changing, 'intersystem' lines of low-Z atomic ions are frequently used in determinations of electron densities and temperatures in astrophysical plasmas as well as in measurements of element abundances in the interstellar gas. The transition probabilities (A-values) of these lines, which are about five orders of magnitude weaker than allowed lines, have not been measured heretofore and various calculations produce A-values for these lines that differ by as much as 50 percent A radio-frequency ion trap has been used for the first measurements of transition probabilities for intersystem lines seen in astronomical spectra. The measurement procedure is discussed and results for Si III, O III, N II, and C III are reviewed and compared to calculated values. Discrepancies exist; these indicate that some of the calculated A-values may be less reliable than has been beleived and that revisions to the electron densities determined for some astrophysical plasmas may be required.
Document ID
19840065327
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Smith, P. L.
(Harvard-Smithsonian Center for Astrophysics Cambridge, MA, United States)
Johnson, B. C.
(Harvard-Smithsonian Center for Astrophysics Cambridge, MA, United States)
Kwong, H. S.
(Harvard-Smithsonian Center for Astrophysics Cambridge, MA, United States)
Parkinson, W. H.
(Harvard-Smithsonian Center for Astrophysics Cambridge, MA, United States)
Knight, R. D.
(Ohio State University Columbus, OH, United States)
Date Acquired
August 12, 2013
Publication Date
January 1, 1984
Publication Information
Publication: Physica Scripta
Volume: T8
ISSN: 0031-8949
Subject Category
Astrophysics
Accession Number
84A48114
Funding Number(s)
CONTRACT_GRANT: NSG-7304
CONTRACT_GRANT: NGL-22-007-006
Distribution Limits
Public
Copyright
Other

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