PARTICULARITIES OF THE COOLING FUNCTION I N CIRCUMSTELLAR FLOWS - INFLUENCE OF THE EXCITED GROUND-CONFIGURATION TERMS ON THE COOLING RATE

Influence of the ground-configuration terms' population on the cooling function has been investigated for the chemical elements C, N, O, Ne, Si, Fe. Energy levels' population and exhaustion under influence of t he electron impact and spontaneous radiative transitions have been tak en into account. The ranges of electron temperature 4<lg T(K)<6 and de nsity 9<lg N(cm-3)<14 have been considered, which are interesting in t he problem of interaction between stars and nearby gas. Results of the calculations were compared with three models of ground-configuration term occupation: 1) approximation of the infinitely small excited-term population (a rarefield gas without star); 2) the term populations ar e proportional to their statistical weights (the model of infinitely h igh excitation temperature T(ex)); 3) the Boltzmann formula for T(ex) = T. The last model is an approximation for cooling function to an acc uracy of 10-20%) in the whole range of temperature and density variati ons.