Cooling functions for low-density astrophysical plasmas

The cooling functions for a plasma slab are investigated under equilibrium and nonequilibrium conditions, over a range of 10 exp 4 - 10 exp 8.5 K and for a range of abundances. Radiative transfer and diffuse field are calculated in the isobaric nonequilibrium models using a one-dimensional cooling flow model, and the plasma is not assumed to be optically thin to all radiation. Limiting cases of the plasma diffuse field coupling are calculated, and the resulting cooling functions are presented. Some functions are terminated before reaching 10 exp 4 K when the internal photoionization halts the cooling. The functions represent a self-consistent set of curves covering a wide grid of temperature and metallicities using recently published atomic data and processes. The results have implications for phenomena such as cooling flows and for hydrodynamic modeling which include gas components.