A note on the opacity of the sun's atmosphere

Abstract

The opacity of the atmosphere of the Sun is due to processes such as Thomson scattering, bound-bound transitions and photodetachment (bound-free) of hydrogen and positronium ions. The well-studied free-free transitions involving photons, electrons, and hydrogen atoms are re-examined, while free-free transitions involving positrons are considered for the first time. Cross sections, averaged over a Maxwellian velocity distribution, involving positrons are comparable to those involving electrons. This indicates that positrons do contribute to the opacity of the atmosphere of the Sun. Accurate results are obtained because definitive phase shifts are known for electron-hydrogen and positron-hydrogen scattering.