On the Dependence of the Two-Level Source Function on its Own Radiation Field
Open Access
- 1 June 1973
- journal article
- Published by Oxford University Press (OUP) in Monthly Notices of the Royal Astronomical Society
- Vol. 162 (3) , 197-206
- https://doi.org/10.1093/mnras/162.3.197
Abstract
The consequences of the universally made assumption that the stimulated emission profile is identical to the absorption profile are quantitatively investigated for a two-level atom with Doppler redistribution. The non-linear terms arising in the source function are evaluated iteratively. We find that the magnitude of the effects are governed by ζ = (exp ( hv / kT ) − 1) −1 and are probably completely negligible for visible and UV solar lines. For ζ = 2 effects of ∼5 per cent are encountered. Larger ζ 's lead to numerical instabilities in the method of solution used.Keywords
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