Forbidden emission lines of NE IV in the optical and ultraviolet spectra of gaseous nebulae
Item Type:Journal Article
Citation:Keenan, F. P. and Aller, L. H. and Bell, K. L. and Espey, B. R. and Feibelman, W. A. and Hyung, S. and McKenna, F. C. and Ramsbottom, C. A. 'Forbidden emission lines of NE IV in the optical and ultraviolet spectra of gaseous nebulae' in Monthly Notices of the Royal Astronomical Society, 295, 1998, pp. 683 ? 690.
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Recent R-matrix calculations of electron impact excitation rates in Ne IV are used to calculate emission line ratio-ratio diagrams involving both the UV (1602, 2422 and 2424 A) and optical (4714, 4716, 4724 and 4726 A) forbidden Ne IV transitions, for a range of electron temperatures and electron densities appropriate to gaseous nebulae. These diagrams should, in principle, allow the simultaneous determination of T(e) and N(e) from measurements of the forbidden Ne IV lines in a spectrum. Plasma parameters deduced for a sample of high-excitation planetary nebulae, using a combination of observational data obtained with the IUE satellite and the Hamilton Echelle Spectrograph (HES) on the 3-m Shane Telescope at the Lick Observatory, are found to show generally excellent internal consistency. In addition, they are in good agreement with the values of T(e) and N(e) estimated from other high-excitation line ratios in the HES spectra, and by previous authors using IR and UV transitions in forbidden O IV and Ne V. These results provide observational support for the accuracy of the theoretical forbidden Ne IV ratios, and hence the atomic data adopted in their derivation
Author: ESPEY, BRIAN RUSSELL
Type of material:Journal Article
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