Continuous Radiation from Regions not in Local Thermodynamic Equilibrium

It is known that at sufficiently low density an optically thin medium cannot be in local thermodynamic equilibrium. For this regime, we employ a model to calculate the maximum deviation of the continuous radiation rate (free—bound and free—free) from this quantity obtained assuming local thermodynamic equilibrium, the usual procedure. The comparison is on the basis of constant energy density (erg/cm3), a quantity independent of local thermodynamic equilibrium. Attention is restricted to local thermodynamic equilibrium temperatures between 1 and 10 eV. It is found that the continuous radiation rate is fairly insensitive to the local thermodynamic equilibrium condition.