Hydrogen Atmospheres in the Absence of Thermodynamic Equilibrium. I. The Populations of the Upper Atomic States

Abstract

From a discussion of the transition rates to and from the upper atomic states of hydrogen it is shown that for temperatures such as occur in the solar chromosphere the populations of the states n> 11 are maintained largely by three-body recombination and collision ionization. Therefore, the populations of these states are distributed as in thermodynamic equilibrium with the electrons even when thermodynamic equilibrium does not exist. These deductions are in agreement with eclipse observations.