Near Thermodynamic Radiative Equilibrium.

Abstract

view Abstract Citations (10) References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Near Thermodynamic Radiative Equilibrium. Henyey, L. G. Abstract Deviations from the excitation and ionization conditions existing in thermodynamic equilibrium, together with the resulting deviations from Kirchhoff's law, are considered. Complete radiative equilibri- um is assumed; hence the deviations mentioned arise from the nonbiack-body nature of the radiation field. The problem is approached from the point of view of first-order perturbations to the conditions of strict thermodynamic equilibrium. The solution of the equations for a steady state is discussed, allowance being made for the finite breadths of the discrete energy states. It is shown that, under the assumption of near thermodynamic equilibrium, the problem reduces to the solution of a set of linear algebraic equations, one for each energy state, the unknowns being the average deviations of the populations of states as a whole from their values in strict equilibrium. The deviations over the breadth of a state follow from the solution in a relatively simple way. The general level of ionization is taken care of in the same way as are the discrete states. However, the details of the ionization are handed by supposing that the free electrons are distributed according to a Maxwell formula with an appropriate electron temperature. This temperature is fixed by the condition that there can exist no net exchange of energy between matter and radiation. The result- ing expressions for the various radiative parameters involve a part which is the equilibrium value of the parameter and a new part. This latter is made up of a linear combination of the deviations, in intensity, from black-body values over the entire spectrum and of a term arising from the difference between the electron temperature and the reference, or approximate, temperature Publication: The Astrophysical Journal Pub Date: May 1946 DOI: 10.1086/144815 Bibcode: 1946ApJ...103..332H full text sources ADS |