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Astron. Astrophys. 364, 157-164 (2000)

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Coulomb corrections to the equation of state for a weakly-coupled plasma

S.L. Bi 1, M.P. Di Mauro 2 and J. Christensen-Dalsgaard 2,3

1 Yunnan Astronomical Observatory, NAOCAS, Chinese Academy of Sciences, Kunming 650011, P.R. China (bsl@cosmos.ynao.ac.cn)
2 Theoretical Astrophysics Center, Danish National Research Foundation
3 University of Aarhus, Institute of Physics and Astronomy, 8000 Aarhus C, Denmark

Received 25 April 2000 / Accepted 28 September 2000


Coulomb corrections to the equation of state of degenerate matter are usually described by Debye-Hückel theory; however, recent studies have considered modifications of thermodynamic quantities which are caused by the interactions of charged particles beyond the Debye-Hückel approximation. Based on the weakly-coupled plasma limit, the formulae for the physical properties of non-ideal effects on the equation of state are derived. The treatment of the non-ideal effects due to Coulomb coupling combines the results of quantum-statistic calculations for the electrons, N-body semianalytic theory for ions, and the extended Debye-Hückel theory with hard-core correction for the electron-ion interaction. The leading Coulomb correction not only can be applied to the weak-coupling region, but also preserves the well-known Debye-Hückel limit at [FORMULA]. We examine the Coulomb correction to the thermodynamic quantities of a weakly coupled and fully ionized plasma. The result reveals that the contribution is quite significant, and hence modifies the thermodynamic properties of the plasma substantially.

Key words: equation of state – Sun: general – stars: interiors

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© European Southern Observatory (ESO) 2000

Online publication: December 15, 2000