Astron. Astrophys. 362, 730-736 (2000)

Emission lines of O III in the optical and ultraviolet spectra of planetary nebulae

F.L. Crawford ¹, F.P. Keenan ¹, K.M. Aggarwal ¹, A.W. Wickstead ², L.H. Aller ³ and W.A. Feibelman <sup>4

1</sup> The Queen's University of Belfast, Department of Pure and Applied Physics, Belfast BT7 1NN, Northern Ireland, UK (fergal.crawford@qub.ac.uk; f.keenan@qub.ac.uk; k.aggarwal@qub.ac.uk)
² The Queen's University of Belfast, Department of Pure Mathematics, Belfast BT7 1NN, Northern Ireland, UK (a.wickstead@qub.ac.uk)
³ University of California, Los Angeles, CA 90024, USA (aller@bonnie.astro.ucla.edu)
⁴ NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA (feibelman@iue.gsfc.nasa.gov)

Received 20 June 2000 / Accepted 8 September 2000

Abstract

Recent R -matrix calculations of electron impact excitation rates in OIII are used to calculate electron temperature and density-dependent emission line ratios

for a range of electron temperatures ( K) and densities ( cm^-3) applicable to gaseous nebulae. The ratio-ratio diagrams (, ) and (, ) should, in principle, allow the simultaneous determination of and from measurements of the OIII features in a spectrum. Plasma parameters derived for a sample of mid- to high-excitation planetary nebulae from (, ) and (, ) measurements, produced using a combination of ultraviolet spectra obtained with the International Ultraviolet Explorer (IUE ) and optical data from a number of observing runs, are found to show excellent internal consistency. They also show, in general, good agreement with the values of and estimated from other line ratios in the nebulae, therefore providing observational support for the accuracy of the theoretical ratios and hence the atomic data adopted in their derivation.

Key words: atomic data ISM: planetary nebulae: general

Send offprint requests to: F.L. Crawford

© European Southern Observatory (ESO) 2000

Online publication: October 24, 2000

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