Application of SAHA-S EOS to solar modeling

摘要

State-of-the-art perspectives of the equation of state (EOS) are considered in view of applications to stellar and solar modeling. While the present-day OPAL EOS is the best-known version of EOS, here we discuss the SAHA-S EOS as an alternative. We assume that the accuracy of the EOS is determined by an adequate description of the ionization of a number of chemical components. To get an adequate description of the ionization, one needs an extensive amount of ion levels, an appropriately truncated partition function, such as the Planck-Larkin function, and a high-level approximation to the Coulomb correction. The current version of the SAHA-S EOS includes an extended set of elements. It provides an accurate profile of the adiabatic exponent in the solar convection zone, which is then compared to a result of a helioseismic inversion.