Emission line diagnostics for a coronal condensation

Abstract

Theoretical line emission rates for the coronal ions Fe X, Fe XI, FE XIII, Fe XIV, Ca XII, Ca XIII, and Ca XV, have been used to obtain various line intensity ratios as a function of electron density and electron temperature. The lines are due to the forbidden transitions in the visible part of the spectrum. With the help of these theoretical line intensity ratios physical parameters for a coronal condensation observed during the eclipse of May 30, 1965 have been derived. A simple model consisting of two regions of equal path length, one at temperature of 1.25 x 10 to the 6th K and the other at 2.5 x 10 to the 6th K and with constant electron density of 5 x 10 to the 8th/cu cm, seems to explain the observed intensities. The analysis also indicates that the observed Ca XIII line intensity appears to be high by about a factor of 4