EFFECTS OF FLOWS AND NONEQUILIBRIUM IONIZATION ON SOME C-IV LINE RATIOS ON THE SUN

We investigate the deviations from ionization equilibrium occurring in coronal loops hosting steady-state siphon flows, and their effects on the EUV emission line ratios of C IV recently considered by Keenan et al. (1992) and found discrepant with observations of highly dynamics events. We use the same electron impact excitation rates adopted by Ke enan et al. and two independent siphon flow models, The C IV line rati os predicted by our models do not differ appreciably between equilibri um and non-equilibrium conditions, and therefore indicate that the dis crepancy found by Keenan et al. (1992) cannot be solved by steady flow s. We discuss alternative solutions, also in view of forthcoming obser vations by CDS/SOHO.