Radiative properties of stellar envelopes: Comparison of asteroseismic results to opacity calculations and measurements for iron and nickel

Turck‐Chièze, S.; Gilles, D.; Pennec, M. Le; Błeński, T.; Thais, F.; Bastiani-Ceccotti, S.; Blancard, C.; Busquet, M.; Caillaud, T.; Colgan, J.; Cossé, Ph.; Delahaye, F.; Ducreta, J.E.; Faussurier, G.; Fontes, Christopher J.; Gilleron, F.; Guzik, Joyce A.; Harris, Julie A.; Kilcrease, D. P.; Loisel, Guillaume; Magee, N. H.; Pain, Jean‐Christophe; Reverdin, C.; Silvert, V.; Villette, B.; Zeippen, C. J.

doi:10.1016/j.hedp.2013.04.004

Cited by 25 publications

(23 citation statements)

References 34 publications

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“…Opacities from ATOMIC have also been recently used to compare with experiments on Fe [21] at conditions near the base of the solar convection zone and Fe and Ni [18,22] at conditions relevant to stellar atmospheres. The major theoretical development in our opacity calculations since our previous report [7] has been the improvement of our equation-of-state (EOS) package, known as ChemEOS [2].…”

Section: Theoretical Developmentsmentioning

confidence: 99%

Light element opacities of astrophysical interest from ATOMIC

Colgan

Kilcrease

Magee

et al. 2015

High Energy Density Physics

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a b s t r a c tWe report on our continued work to produce a new set of local-thermodynamic-equilibrium (LTE) opacity tables using the Los Alamos ATOMIC code. OPLIB tables for the 30 elements from H through Zn are almost complete and are expected to be available in 2015. In this paper we present some examples of our new opacities from ATOMIC. We provide comparisons of our opacities with a series of opacity measurements that were performed on Fe and Al some years ago. We also present opacities at conditions of interest to stellar modeling and compare and contrast the opacity of various transition metals with OP calculations that are commonly used in astrophysical modeling.

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Section: Theoretical Developmentsmentioning

confidence: 99%

Light element opacities of astrophysical interest from ATOMIC

Colgan

Kilcrease

Magee

et al. 2015

High Energy Density Physics

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“…In this respect, the versatile HULLAC relativistic code [87] has been used to study CI effects mainly in 3 → 3 and 3 → 4 transitions that dominate the maximum of the RMO [19]. At T = 27.3 eV and ρ = 3.4 mg cm −3 , it is found that CI causes noticeable changes in the spectrum shape due to line shifts at the lower photon energies; good agreement is found with OP in contrast to the spectra by other codes such as SCO-RCG, LEDCOP, and OPAS.…”

Section: Fe Opacitymentioning

confidence: 99%

“…At T = 27.3 eV and ρ = 3.4 mg cm −3 , it is found that CI causes noticeable changes in the spectrum shape due to line shifts at the lower photon energies; good agreement is found with OP in contrast to the spectra by other codes such as SCO-RCG, LEDCOP, and OPAS. The importance of CI is also brought out in comparisons of the OP and OPAL monochromatic opacities with old transmission measurements, namely spectral energy displacements [19]. However, a further comparison [31] with recent results at T = 15.3 eV and ρ = 5.48 mg cm −3 obtained with the ATOMIC modeling code, results that include contributions from transitions with n ≤ 5, shows significantly higher monochromatic opacities than OP for photon energies greater than 100 eV and almost a factor of 2 increase in the RMO; it is pointed out therein that this is due to limited M-shell configuration expansions in OP for ions such as Fe VIII. A more controversial situation involves the recently measured Fe monochromatic opacities that proved to be higher that expected in conditions similar to the solar CZB [33].…”

Section: Fe Opacitymentioning

confidence: 99%

Computation of Atomic Astrophysical Opacities

Mendoza

2018

Atoms

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Abstract:The revision of the standard Los Alamos opacities in the 1980-1990s by a group from the Lawrence Livermore National Laboratory (OPAL) and the Opacity Project (OP) consortium was an early example of collaborative big-data science, leading to reliable data deliverables (atomic databases, monochromatic opacities, mean opacities, and radiative accelerations) widely used since then to solve a variety of important astrophysical problems. Nowadays the precision of the OPAL and OP opacities, and even of new tables (OPLIB) by Los Alamos, is a recurrent topic in a hot debate involving stringent comparisons between theory, laboratory experiments, and solar and stellar observations in sophisticated research fields: the standard solar model (SSM), helio and asteroseismology, non-LTE 3D hydrodynamic photospheric modeling, nuclear reaction rates, solar neutrino observations, computational atomic physics, and plasma experiments. In this context, an unexpected downward revision of the solar photospheric metal abundances in 2005 spoiled a very precise agreement between the helioseismic indicators (the radius of the convection zone boundary, the sound-speed profile, and helium surface abundance) and SSM benchmarks, which could be somehow reestablished with a substantial opacity increase. Recent laboratory measurements of the iron opacity in physical conditions similar to the boundary of the solar convection zone have indeed predicted significant increases (30-400%), although new systematic improvements and comparisons of the computed tables have not yet been able to reproduce them. We give an overview of this controversy, and within the OP approach, discuss some of the theoretical shortcomings that could be impairing a more complete and accurate opacity accounting.

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“…The pulsation properties of such stars were recently explored using our new Los Alamos opacities. Previous work (Gilles et al 2011;Turck-Chièze et al 2013) has cast some doubt on the use of the OP database for such systems. In particular, the Ni OP opacities, which made use of scaled atomic data (Badnell et al 2005) were found to be in significant disagreement with several other sets of opacity calculations (Turck-Chièze et al 2013).…”

Section: Single-element Opacity Comparisonsmentioning

confidence: 99%

“…Previous work (Gilles et al 2011;Turck-Chièze et al 2013) has cast some doubt on the use of the OP database for such systems. In particular, the Ni OP opacities, which made use of scaled atomic data (Badnell et al 2005) were found to be in significant disagreement with several other sets of opacity calculations (Turck-Chièze et al 2013). Studies of Fe opacities at these conditions, including previous ATOMIC calculations (Colgan et al 2013a), also indicated that several important inner-shell transitions may have been omitted from the OP calculations, a conclusion also reached by Iglesias (2015b).…”

Section: Single-element Opacity Comparisonsmentioning

confidence: 99%

A new generation of Los Alamos opacity tables

Colgan¹,

Kilcrease²,

Magee³

et al. 2017

AIP Conference Proceedings

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We present a new, publicly available, set of Los Alamos OPLIB opacity tables for the elements hydrogen through zinc. Our tables are computed using the Los Alamos ATOMIC opacity and plasma modeling code, and make use of atomic structure calculations that use fine-structure detail for all the elements considered. Our equation-of-state (EOS) model, known as ChemEOS, is based on the minimization of free energy in a chemical picture and appears to be a reasonable and robust approach to determining atomic state populations over a wide range of temperatures and densities. In this paper we discuss in detail the calculations that we have performed for the 30 elements considered, and present some comparisons of our monochromatic opacities with measurements and other opacity codes. We also use our new opacity tables in solar modeling calculations and compare and contrast such modeling with previous work.

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Radiative properties of stellar envelopes: Comparison of asteroseismic results to opacity calculations and measurements for iron and nickel

Cited by 25 publications

References 34 publications

Light element opacities of astrophysical interest from ATOMIC

Light element opacities of astrophysical interest from ATOMIC

Computation of Atomic Astrophysical Opacities

A new generation of Los Alamos opacity tables

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