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N IV emission lines in the ultraviolet spectra of gaseous nebulaeTheoretical electron density sensitive emission-line ratios, determined using electron impact excitation rates calculated with the R-matrix code, are presented for R = I(2s(sup 2) (1)S-2s2p 3P(sub 2))/I(2s(sup 2) (1)S-2s2p 3P(sub 1) = 1(1483 A)/I(1486 A) in N IV. These are found to be up to an order of magnitude different from those deduced by previous authors, principally due to the inclusion of excitation rates for transitions among the 2s2p (3)p fine-structure levels. The observed values of R for several planetary nebulae, symbiotic stars and the Cygnus Loop supernova remnant, measured from spectra obtained with the International Ultraviolet Explorer (IUE) satellite and the Hopkins Ultraviolet Explorer (HUT), lead to electron densities which are in excellent agreement with those deduced from line ratios in other species. This provides observational support for the accuracy of the atomic data adopted in the present calculations.
Document ID
19950048273
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Keenan, F. P.
(Queen's Univ. of Belfast, Belfast, United Kingdom)
Ramsbottom, C. A.
(Queen's Univ. of Belfast, Belfast, United Kingdom)
Bell, K. L.
(Queen's Univ. of Belfast, Belfast, United Kingdom)
Berrington, K. A.
(Queen's Univ. of Belfast, Belfast, United Kingdom)
Hibbert, A.
(Queen's Univ. of Belfast, Belfast, United Kingdom)
Feibelman, W. A.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Blair, W. P.
(Johns Hopkins Univ. Baltimore, MD, United States)
Date Acquired
August 16, 2013
Publication Date
January 1, 1995
Publication Information
Publication: Astrophysical Journal, Part 1
Volume: 438
Issue: 1
ISSN: 0004-637X
Subject Category
Astronomy
Accession Number
95A79872
Distribution Limits
Public
Copyright
Other

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