Interpretation of Solar Helium-Like Ion Line Intensities

Abstract

Recent identification of the |${2}^{3}\,S\rightarrow {1}^{1}\,S$| line from helium-like ions in the solar soft X-ray spectrum, followed by calculation of its transition probability, enables an analysis of the observations to be carried out, based on intensities of the three lines |${2}^{1}\,\text{P}\rightarrow {1}^{1}\,S,\,{2}^{3}P\rightarrow {1}^{1}S,\text{and}\,{2}^{3}\,S\rightarrow {1}^{1}S$|⁠. The relative collision rates to the excited levels and the electron densities in the emitting regions have been determined, subject to the limitation of available observations. Densities of |$\simeq 3\,\times {10}^{8}\,\text{cm}^{-3}$| are found from lines formed over the quiet corona, but values of between 109 and 1011 cm–3 are found from lines emitted in active regions, and the highest electron densities occur in the hottest regions.