Ultraviolet pumping of N/+/ fine-structure levels

Abstract

view Abstract Citations (12) References (12) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Ultraviolet pumping of N+ fine-structure levels. Flannery, B. P. ; Rybicki, G. B. ; Sarazin, C. L. Abstract The effects of radiative pumping, through the six-line UV 3D - 3P multiplet at 1085 A, on the population of the fine-structure levels of N(+) are investigated. Results are presented for both optically thin and optically thick media. For the more important case of an optically thick nebula, an efficient method is outlined for the numerical solution of the multiline multilevel radiative-transfer problem in a model H II region described by plane-parallel geometry, point source illumination, and homogeneous physical conditions. The method is applied to construct a grid of models for N(+) spanning a wide range of values for the electron density, the strength of the UV source, and the line optical depth of the nebula. In general it is found that radiative pumping and transfer effects can significantly alter the level populations, but the effect often mimics results obtained without radiative pumping with a different electron density. For Stroemgren spheres around early-type stars it is found as a result of transfer effects, the role of pumping is never likely to be important. Infrared emission from the fine-structure decays at 122 and 240 microns is also discussed. Publication: The Astrophysical Journal Pub Date: May 1979 DOI: 10.1086/157040 Bibcode: 1979ApJ...229.1057F Keywords: Fine Structure; Nebulae; Nitrogen Ions; Optical Pumping; Ultraviolet Astronomy; Atomic Excitations; Doppler Effect; Electron Density (Concentration); Energy Levels; H Ii Regions; Lyman Spectra; Radiative Transfer; Statistical Distributions; Stellar Evolution; Stellar Spectra; Astrophysics; H II Regions:Radiative Transfer; Line Formation full text sources ADS |