About equations of state and other quantities related to microphysics

¹ Université de Lyon, 69003
Université Lyon 1, Observatoire de Lyon, 9 avenue Charles André, Saint-Genis Laval, 69230, France
CNRS, UMR 5574, Centre de Recherche Astrophysique de Lyon; École Normale Supérieure de Lyon, 69007, France

Abstract

Stellar modelling challenges the physicist to provide accurate data for a lot of processes in a wide range of conditions. This ends in the use of patchy results from microscopic models that aimed initially at peculiar physical domains. Very often various quantities such as thermodynamics quantities, opacities, diffusion coefficients or conductivities, are obtained from different sources. It is thus of importance to construct first principles models of general application. We focus this talk on warm dense matter, as encountered in low-mass or compact stars, and where pressure ionization has dramatic effects. We present equation of state computations from a model we have developed that treat quantum mechanically bound as well as delocalized electrons. It goes beyond the usual Average-Atom models in treating separately ionic charges, and extends from low to high densities. On the experimental side recent years have seen significant advances in the creation and the diagnostics of plasmas under these extreme conditions. A brief account will be given on what might be expected as far as quantities of astrophysical interest are concerned.