Fe III Emission Lines in the Optical Spectrum of the Planetary Nebula IC 4997
Abstract
Relative populations for the 17 fine-structure levels in the 5D, 3P, 3H, 3F, and 3G states of the 3d6 configuration in Fe III, calculated using electron impact excitation rates derived with the R-matrix code, are used to derive theoretical electron temperature and density sensitive emission-line ratios applicable to the spectra of astronomical objects in the 4607-5412 A wavelength range. A comparison of these with high spectral resolution observational data for the PN IC 4997 reveals generally good agreement between theory and observation. This provides experimental support for the accuracy of the theoretical ratios and illustrates their usefulness in determining plasma parameters for the Fe III-emitting region of a gaseous nebula.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- June 1993
- DOI:
- 10.1086/172760
- Bibcode:
- 1993ApJ...410..430K
- Keywords:
-
- Emission Spectra;
- Iron;
- Planetary Nebulae;
- Visible Spectrum;
- Electron Density (Concentration);
- Electron Energy;
- Electron Transitions;
- Astrophysics