The excitation of the forbidden coronal lines.

The excitation of the 2s2p ground configuration of Ca xv is calculated for coronal densities and temperatures. The calculations include electron and proton excitation of the forbidden transitions and electron excitation via the first excited (2s2p) configuration. It is shown that measurements of the line intensity ratio I(λ 5694)/ I(λ 5446) are in good agreement with the predictions. The line to continuum observations for limb flares and coronal condensations are discussed. It is suggested that the calcium abundance in condensations is enhanced owing to diffusion processes. [ABSTRACT FROM AUTHOR]