The Coronal Emission Spectrum

Abstract

The ionization in the corona is computed by supposing it to be determined by a balance between ionization by electron impacts and photoelectric recombinations. The results for an electron temperature of 10 ⁶ , degrees agree with experiment. An estimate of the abundance of elements in the corona, from coronal line intensities in relation to the electron scatter continuum, gives a hydrogen to metal ratio of 6000: 1 by numbers. The collision excitation cross-section of Fe XIV 5303 A . is found to be $$0.26\pi a_0^2$$ by a method which does not assume the abundance of Fe XIV. The coronal emission in discrete lines, in bound-free continua, and in free-free continua, is separately computed. It is found that the principal lings of Mg X at 610 A . are strong in emission. It is suggested that the emission from the chromosphere in the Lyman continuum is stronger than the coronal emission, and the effects on the ionosphere of these spectra are briefly reviewed.