SIMBAD references

Hydrogen recombination is one of the most important atomic processes in many astrophysical objects such as Type II supernova (SN II) atmospheres, the high redshift Universe during the cosmological recombination era and HII regions in the interstellar medium. Accurate predictions of the ionization fraction can be quite different from those given by a simple solution if one takes into account many angular momentum substates, non-resonant processes and calculates the rates of all atomic processes from the solution of the radiative transfer equation instead of using a Planck function under the assumption of thermal equilibrium. We use the general-purpose model atmosphere code phoenix 1D to compare how the fundamental probabilities such as the photoionization probability, the escape probability and the collisional de-excitation probability are affected by the presence of other metals in the environment, multiple angular momentum substates and non-resonant processes. Our comparisons are based on a model of SN 1999em, SNe Type II, 20 d after its explosion.