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Open AccessFeature PaperArticle

Detailed Opacity Calculations for Astrophysical Applications

CEA, DAM, DIF, F-91297 Arpajon, France
Author to whom correspondence should be addressed.
Academic Editor: James F. Babb
Atoms 2017, 5(2), 22;
Received: 30 January 2017 / Revised: 2 May 2017 / Accepted: 16 May 2017 / Published: 30 May 2017
(This article belongs to the Special Issue Atomic and Molecular Opacity Data for Astrophysics)
Nowadays, several opacity codes are able to provide data for stellar structure models, but the computed opacities may show significant differences. In this work, we present state-of-the-art precise spectral opacity calculations, illustrated by stellar applications. The essential role of laboratory experiments to check the quality of the computed data is underlined. We review some X-ray and XUV laser and Z-pinch photo-absorption measurements as well as X-ray emission spectroscopy experiments involving hot dense plasmas produced by ultra-high-intensity laser irradiation. The measured spectra are systematically compared with the fine-structure opacity code SCO-RCG. The focus is on iron, due to its crucial role in understanding asteroseismic observations of β Cephei-type and Slowly Pulsating B stars, as well as of the Sun. For instance, in β Cephei-type stars, the iron-group opacity peak excites acoustic modes through the “kappa-mechanism”. Particular attention is paid to the higher-than-predicted iron opacity measured at the Sandia Z-machine at solar interior conditions. We discuss some theoretical aspects such as density effects, photo-ionization, autoionization or the “filling-the-gap” effect of highly excited states. View Full-Text
Keywords: atomic physics; spectroscopy; astrophysics; β Cephei; white dwarfs; stellar envelopes; radiative zone of the Sun atomic physics; spectroscopy; astrophysics; β Cephei; white dwarfs; stellar envelopes; radiative zone of the Sun
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Pain, J.-C.; Gilleron, F.; Comet, M. Detailed Opacity Calculations for Astrophysical Applications. Atoms 2017, 5, 22.

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