SIMBAD references

The role of iron for the energy balance in the extended atmospheres and circumstellar envelopes of cool stars is explored. Based on large non-LTE model atoms for FeI and FeII, we study the influence of fine-structure, forbidden, permitted and bound-free transitions on the radiative heating and cooling of the gas under various temperature, density and radiation field conditions. The results are compared to those obtained in LTE and to those calculated when ignoring optical depth effects in the lines. The number of levels in the model atoms necessary to achieve convergence of the results is discussed.