Influence of chemi-ionization and chemi-recombination processes on the population of hydrogen Rydberg states in atmospheres of late type dwarfs

We study the influence of a group of chemi-ionization and chemi-recombination processes on the populations of higher states of hydrogen in the layers of a stellar atmosphere. The group of processes includes ionization: H*(n)+H(ls)(right arrow)H+2+e , H*(n)+H)ls) (right arrow)H(ls)+H^++e, and inverse recombination: H+2+e(right arrow)H*(n)+H(ls), H(ls)+H^++e(right arrow)H*(n)+H(ls),where H*(n) is the hydrogen atom in a state with the principal quantum number N(greater than)1, and H+2 is the hydrogen molecular ion in a weakly bound rho-vibrational state of the ground state. These processes have been treated within the framework of the semi-classical approximation, developed in several previous papers, and have been included in the general stellar atmosphere code PHOENIX. We present results for an M dwarf atmosphere with Teff = 3800 K and find that the inclusion of chemi-ionization and chemi-recombination processes is significant in the low temperature parts of the atmosphere.