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Paper: Radiative Properties of Stellar Plasma
Volume: 462, Progress in Solar/Stellar Physics with Helio- and Asteroseismology
Page: 95
Authors: Turck-Chièze, S.; Loisel, G.; Gilles, D.; Ducret, J. E.; Piau, L.; Blenski, T.; Poirier, M.; Thais, F.; Bastiani, S.; Blancard, C.; Busquet, M.; Caillaud, T.; Cossé, P.; Delahaye, F.; Faussurier, G.; Gilleron, F.; Guzik, J. A.; Harris, J. W.; Kilcrease, D. P.; Magee, N. H.; Pain, J. C.; Porcherot, Q.; Reverdin, C.; Silvert, V.; Villette, B.; Zeippen, C.
Abstract: Opacity cross-section is an important ingredient of the secular evolution of stars. But calculation of the opacity coefficients is complex because of the partially ionized medium (Z ≤ 28) ion contributions to a mixture dominated by H/He. This implies that a very large number of lines must be considered to describe M or L transitions and produce the mean Rosseland values. Up to now the astrophysical community has greatly benefited from the work of the Los Alamos and Livermore teams and also from the academic Opacity Project tables producing also the corresponding energy spectra. Despite some opacity measurements performed at the beginning of the nineties and related progress, differences in the radiative forces and Rosseland mean values are still noticed with a real impact on asteroseismic interpretations or on diffusion in stellar models. So a new effort has been engaged these last three years to interpret the large number of data presently available with Solar and Heliospheric Observatory (SoHO), CoRoT and Kepler. High energy laser and Z-pinch facilities produce plasma in conditions of temperature and density useful for stellar conditions, and a new series of measurements have been performed recently. In parallel several new calculations have been done using OPAS, SCORCG, HULLAC codes to compare with new measurements and other codes on medium elements. The present consortium carefully checks the origin of the discrepancies between codes. We present and mention here some results and suggest a strategy for the years to come.
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