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Nagayama T, Bailey JE, Loisel GP, Dunham GS, Rochau GA, Blancard C, Colgan J, Cossé P, Faussurier G, Fontes CJ, Gilleron F, Hansen SB, Iglesias CA, Golovkin IE, Kilcrease DP, MacFarlane JJ, Mancini RC, More RM, Orban C, Pain JC, Sherrill ME, Wilson BG. Systematic Study of L-Shell Opacity at Stellar Interior Temperatures. PHYSICAL REVIEW LETTERS 2019; 122:235001. [PMID: 31298873 DOI: 10.1103/physrevlett.122.235001] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Indexed: 06/10/2023]
Abstract
The first systematic study of opacity dependence on atomic number at stellar interior temperatures is used to evaluate discrepancies between measured and modeled iron opacity [J. E. Bailey et al., Nature (London) 517, 56 (2015)NATUAS0028-083610.1038/nature14048]. High-temperature (>180 eV) chromium and nickel opacities are measured with ±6%-10% uncertainty, using the same methods employed in the previous iron experiments. The 10%-20% experiment reproducibility demonstrates experiment reliability. The overall model-data disagreements are smaller than for iron. However, the systematic study reveals shortcomings in models for density effects, excited states, and open L-shell configurations. The 30%-45% underestimate in the modeled quasicontinuum opacity at short wavelengths was observed only from iron and only at temperature above 180 eV. Thus, either opacity theories are missing physics that has nonmonotonic dependence on the number of bound electrons or there is an experimental flaw unique to the iron measurement at temperatures above 180 eV.
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Affiliation(s)
- T Nagayama
- Sandia National Laboratories, Albuquerque, New Mexico 87185, USA
| | - J E Bailey
- Sandia National Laboratories, Albuquerque, New Mexico 87185, USA
| | - G P Loisel
- Sandia National Laboratories, Albuquerque, New Mexico 87185, USA
| | - G S Dunham
- Sandia National Laboratories, Albuquerque, New Mexico 87185, USA
| | - G A Rochau
- Sandia National Laboratories, Albuquerque, New Mexico 87185, USA
| | | | - J Colgan
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Ph Cossé
- CEA, DAM, DIF, F-91297 Arpajon, France
| | | | - C J Fontes
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | | | - S B Hansen
- Sandia National Laboratories, Albuquerque, New Mexico 87185, USA
| | - C A Iglesias
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - I E Golovkin
- Prism Computational Sciences, Madison, Wisconsin 53711, USA
| | - D P Kilcrease
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - J J MacFarlane
- Prism Computational Sciences, Madison, Wisconsin 53711, USA
| | - R C Mancini
- University of Nevada, Reno, Nevada 89557, USA
| | - R M More
- Sandia National Laboratories, Albuquerque, New Mexico 87185, USA
| | - C Orban
- Ohio State University, Columbus, Ohio 43210, USA
| | - J-C Pain
- CEA, DAM, DIF, F-91297 Arpajon, France
| | - M E Sherrill
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - B G Wilson
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
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Abstract
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.
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