Influence of chemi-ionization and chemi-recombination processes on hydrogen line shapes in M dwarfs

Abstract

Aims. We study the influence of chemi-ionization in H*(n) + H(1s) collisions and inverse chemi-recombination processes on the population of higher levels and consequently on profiles of hydrogen lines in the atmospheres of late type (M) stars. Methods. Modeling, using general stellar atmosphere code PHOENIX to reveal the importance of the inclusion of such processes. Results. We demonstrate for the first time observationally detectable effects of these chemi-processes on stellar spectra. Conclusions. It is very important to include chemi-ionization and chemi-recombination processes in modeling of atmospheres of late type stars, especially if one wants to use line profiles for diagnostics of stellar photospheres and lower chromospheres. © ESO 2007.