The NII spectrum of the Orion Nebula

Abstract

The predicted emission spectrum of NII is compared with observations of permitted lines in the Orion nebula. Conventional nebular models show that the intensities of the more intense lines can be explained by fluorescence of starlight absorption with a N abundance that is consistent with forbidden lines. Lines excited mostly by recombination on the other hand predict high N abundances. The effects of stellar and nebular parameters and of the atomic data on the predicted intensities are examined.

arXiv comment12 pages, 7 figures, to appear in MNRAS

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• Very deep spectroscopy of the bright Saturn Nebula NGC 7009 - II. Analysis of the rich optical recombination spectrum
• Excitation of emission lines by fluorescence and recombination in IC418
• The GALAH survey: Characterization of emission-line stars with spectral modelling using autoencoders
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• Physical Conditions and Chemical Abundances of the Variable Planetary Nebula IC 4997