Ultraviolet pumping of Si/+/ fine-structure levels

Abstract

view Abstract Citations (12) References (15) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Ultraviolet pumping of Si/+/ fine-structure levels Flannery, B. P. ; Rybicki, G. B. ; Sarazin, C. L. Abstract The effects of ultraviolet pumping on the population of the doublet fine-structure levels of Si(+) are investigated, and an efficient method for the numerical solution of the multi-line, multi-level radiative transfer problem is presented. Following a review of the atomic properties of Si(+), analytic results are presented for optically thin pumping through eight UV levels with 16 lines in the wavelength range 990-1820 A. Consideration is then given to the radiative transfer problem for pumping in an optically thick medium, and the method employed for the numerical solution of the problem is introduced which is based on a core saturation approximation for the statistical equilibrium equations. Numerical results are then presented for a grid of homogeneous plane parallel nebulae illuminated by a point source, which are characterized by a wide range of electron densities, UV source strengths and line optical depths. Applications of the results to Stromgren spheres and an absorption system in the quasar PKS 0237-23 are discussed. Publication: The Astrophysical Journal Supplement Series Pub Date: December 1980 DOI: 10.1086/190705 Bibcode: 1980ApJS...44..539F Keywords: Atomic Energy Levels; Fine Structure; Optical Pumping; Positive Ions; Quasars; Radiative Transfer; Silicon; Ultraviolet Spectra; Absorption Spectra; Atomic Physics; Line Spectra; Optical Thickness; Populations; Astrophysics full text sources ADS |