OBSERVATIONAL EVIDENCE FOR NONEQUILIBRIUM IONIZATION IN THE SOLAR CORONA

We investigate whether temperature sensitive EUV line ratios can be us ed as observational signatures for the presence of non-equilibrium ion ization in transition region plasma. We compute the total intensity of some EUV lines of carbon and oxygen expected from coronal loop models with a steady-state flow and which are known to have significant depa rtures from ionization equilibrium, selecting lines whose intensity ra tios are useful for deducing the electron temperature in the coronal p lasma. We calculate the intensity ratios with and without the approxim ation of ionization equilibrium, in order to determine the effects of any deviations from equilibrium on the numerical values of the line ra tios examined.