New Los Alamos Opacity Calculations

Colgan, J.; Kilcrease, D. P.; Magee, N. H.; Sherrill, M. E.; Fontes, Christopher J.; Hakel, P.

doi:10.3390/atoms6020032

Cited by 6 publications

(3 citation statements)

References 31 publications

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“…Neither possibility can be ruled out until experiment and theory are reconciled. Experimental [11,[14][15][16][17][18] and theoretical investigations [19][20][21][22][23][24] done up to now have not resolved the discrepancy.…”

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confidence: 99%

“…Selected comparisons (Fig. 4) over the BB and window regions with ATOMIC [19], OPAS [42], SCO-RCG [43], SCRAM [44], and TOPAZ [45] show that all these models predict the BB transition energies more accurately than OP. A couple of these models are beginning to be used for detailed solar structure calculations [19,[46][47][48][49][50][51] though their codes are not publicly available.…”

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confidence: 99%

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Systematic Study of L -Shell Opacity at Stellar Interior Temperatures

et al. 2019

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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 517, 56 (2015)]. Hightemperature (>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 short-wavelength quasi-continuum opacity was observed only from iron and only at temperature above 180 eV. Thus, either opacity theories are missing physics that has non-monotonic 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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Systematic Study of L -Shell Opacity at Stellar Interior Temperatures

et al. 2019

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“…Masses and dimensions of the sample must be well-known. In order to compare with LTE opacity codes (see for instance [37][38][39][40]), it is crucial to ensure that the plasma is actually in LTE. Quantitative information on the opacity can be obtained only if the following requirements are satisfied [41][42][43]:…”

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confidence: 99%

A quantitative study of some sources of uncertainty in opacity measurements

Pain

Gilleron

2020

High Energy Density Physics

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Laboratory (laser and Z-pinch) opacity measurements of well-characterized plasmas provide data to assist inertial confinement fusion, astrophysics and atomic-physics research. In order to test the atomic-physics codes devoted to the calculation of radiative properties of hot plasmas, such experiments must fulfill a number of requirements. In this work, we discuss some sources of uncertainty in absorption-spectroscopy experiments, concerning areal mass, background emission, intensity of the backlighter and self-emission of the plasma. We also study the impact of spatial non-uniformities of the sample.

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Shock cooling emission from explosions of red supergiants – I. A numerically calibrated analytic model

Morag

Sapir

Waxman

2023

Monthly Notices of the Royal Astronomical Society

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Supernova light curves are dominated at early time, hours to days, by photons escaping from the expanding shock heated envelope. We provide a simple analytic description of the time dependent luminosity, L, and color temperature, Tcol, for explosions of red supergiants (with convective polytropic envelopes), valid up to H recombination (T ≈ 0.7 eV). The analytic description interpolates between existing expressions valid at different (planar then spherical) stages of the expansion, and is calibrated against numerical hydrodynamic diffusion calculations for a wide range of progenitor parameters (mass, radius, core/envelope mass and radius ratios, metalicity), and explosion energies. The numerically derived L and Tcol are described by the analytic expressions with $10{{\%}}$ and $5{{\%}}$ accuracy respectively. Tcol is inferred from the hydrodynamic profiles using frequency independent opacity, based on tables we constructed for this purpose (and will be made publicly available) including bound-bound and bound-free contributions. In an accompanying paper (Paper II) we show, using a large set of multi-group photon diffusion calculations, that the spectral energy distribution is well described by a Planck spectrum with T = Tcol, except at UV frequencies, where the flux can be significantly suppressed due to strong line absorption. We defer the full discussion of the multi-group results to paper II, but provide here for completeness an analytic description also of the UV suppression. Our analytic results are a useful tool for inferring progenitor properties, explosion velocity, and also relative extinction based on early multi-band shock cooling observations of supernovae.

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New Los Alamos Opacity Calculations

Cited by 6 publications

References 31 publications

Systematic Study of L -Shell Opacity at Stellar Interior Temperatures

Systematic Study of L -Shell Opacity at Stellar Interior Temperatures

A quantitative study of some sources of uncertainty in opacity measurements

Shock cooling emission from explosions of red supergiants – I. A numerically calibrated analytic model

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