EXCITATION OF FORBIDDEN CORONAL LINES .I. FE-XIII LAMBDALAMBDA10747, LAMBDALAMBDA10798, AND LAMBDALAMBDA3388

The excitation of the lowest (3s23p2) configuration of Fe xiii is discussed for the range of density and temperatures experienced in the solar corona. The principal features are the introduction of proton collisions as an important mechanism for exciting the 3p23P levels, the use of improved electron collision strengths and a detailed discussion of the influence of the excited configurations. The predicted intensity ratios are shown to be consistent with available observations with the single exception of an eclipse measurement of the ratio of the intensities of the infrared lines. © 1969 D. Reidel Publishing Company.