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

¹ Institute of Physics, PO Box 57, 11001 Belgrade, Serbia and Montenegro
² Institute Isaac Newton of Chile, Yugoslavia Branch, Belgrade, Serbia and Montenegro
³ APS Division, Phys. Depart., Queen's University Belfast, BT7 1NN, Northern Ireland, UK
⁴ Astronomical Observatory, Volgina 7, 11160 Belgrade, Serbia and Montenegro
⁵ Depart. of Phys. and Astronomy and Center for Simulat. Physics, University of Georgia, Athens, GA 30602, USA
⁶ Hamburger Sternwarte, Universitaet Hamburg, Gojenbergsweg 112, 21029 Hamburg, Germany
⁷ CRAL/ENS, 46 Allée d'Italie, 69634 Lyon Cedex 07, France

Corresponding author: M. S. Dimitrijević, mdimitrijevic@aob.bg.ac.yu

Received: 22 July 2002
Accepted: 4 February 2003

Abstract

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: , , and inverse recombination: , , where is the hydrogen atom in a state with the principal quantum number , and 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  = 3800 K and find that the inclusion of chemi-ionization and chemi-recombination processes is significant in the low temperature parts of the atmosphere.