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New solar opacities, abundances, helioseismology, and neutrino fluxes

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John N. Bahcall, Aldo M. Serenelli, Sarbani Basu

Astrophysics · Submitted 16 Dec 2004 · 19 references

Pith's verdict: A clean, correctly scoped negative result: the new OP opacities do not rescue the low-abundance solar models, and the helioseismic failure is large enough that it doesn't depend on which opacity library you pick.

T0 · AI review

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arXiv IDastro-ph/0412440 (version 3)
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CitationAldo M. Serenelli, John N. Bahcall, Sarbani Basu. "New solar opacities, abundances, helioseismology, and neutrino fluxes." arXiv:astro-ph/0412440 (2004). https://pith.science/paper/PDDWSJHA
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The paper

The paper claims

The Sun's newly lowered metal abundance breaks standard solar models, and the newest opacity calculations do not repair them.

The reading

The paper asks a narrow question with a large consequence: when the Sun's surface heavy-element abundances are revised downward, can a matching revision of the radiative opacity — the physics that controls how heat leaks outward through the solar interior — rescue the standard solar model? The authors build seven precise solar models, spanning two independent stellar-evolution codes, two opacity libraries (OPAL and the newly recalculated Opacity Project set), two abundance determinations, and an updated nuclear cross section for $^{14}$N(p,$gamma$)$^{15}$O. The models with the older, larger abundances sit comfortably inside the helioseismological error bars on the depth of the convective zone, the surface helium abundance, the sound-speed profile, and the density profile; the models with the newer, lower abundances miss by many times the quoted errors. The new Opacity Project opacities come out less than 2.5% above OPAL everywhere that matters, far short of the roughly 10% increase between 2 and 4.5 million kelvin that earlier work suggested would be needed. The payoff is a clean separation: solar neutrino predictions stay in good agreement with the Sudbury Neutrino Observatory and with the measured p-p flux under every variation considered, so the tension is confined to the interior structure, not to the neutrino physics.

What carries the argument

The load-bearing device is a controlled matrix of solar models: hold the physics fixed, vary one input at a time, and read off both helioseismic diagnostics and neutrino fluxes. The two axes are the radiative opacity library (OPAL versus the new Opacity Project calculation) and the surface heavy-element mixture (Grevesse and Sauval 1998 versus Asplund, Grevesse and Sauval 2005), with a third refinement being the measured low-energy cross section $S_{1,14} = 1.7 pm 0.2$ keV b for $^{14}$N(p,$gamma$)$^{15}$O, which nearly halves the predicted $^{13}$N and $^{15}$O neutrino fluxes and drops the CNO contribution to solar luminosity from 1.55% to 0.8%. Each model is calibrated to the present solar luminosity and radius by adjusting the initial helium abundance and the convective mixing length, so the outputs — $R_{CZ}$, $Y_{mathrm{surf}}$, sound speed, density, and the eight neutrino fluxes — are predictions rather than fits. The comparison standards are the helioseismic inversions of Basu and Antia (2004) for $R_{CZ}$ and $Y_{mathrm{surf}}$, the MDI sound-speed and density profiles of Schou et al. (1998), and the SNO total $^{8}$B flux.

Extended reading notes

Core claim

The paper establishes that the disagreement between helioseismology and solar models built with the Asplund, Grevesse and Sauval (2005) heavy-element abundances survives both a change of opacity library and a change of stellar-evolution code. For the model BS05(AGS,OP), the computed depth of the convective zone is $R_{CZ}/R_odot = 0.728$ against a measured $0.713 pm 0.001$, and the computed surface helium abundance is $Y_{mathrm{surf}} = 0.229$ against a measured $0.249 pm 0.003$; both miss by many times the quoted errors. The root-mean-square differences between model and helioseismic sound speeds and densities are more than a factor of three larger for the low-abundance models than for the Grevesse and Sauval (1998) models. Because the new Opacity Project opacities exceed OPAL by less than 2.5% over the relevant temperature range, the authors conclude that improved opacity calculations of this kind do not remove the discrepancy. A secondary result the authors emphasize is that two independently written stellar-evolution codes reproduce the same solar model to extraordinary precision — initial helium to about 0.04%, convective-zone depth to about 0.01%, and the $^{7}$Be, $^{8}$B, $^{17}$F and pep neutrino fluxes to 0.4% or better — which means even small model-versus-observation gaps deserve to be taken seriously.

Load-bearing premise

The conclusion that opacity cannot explain the mismatch assumes that the OP and OPAL libraries together pin down the true radiative opacity to better than the roughly 10% increase that would be needed, even though the two share much of their underlying atomic physics.

Editorial extensions

If this is right

  • If the result holds, the solar abundance problem is a genuine failure of standard solar modeling rather than a bookkeeping artifact of one opacity library, and it must be resolved by revising either the abundance determination or the input physics other than opacity.
  • The solar neutrino predictions are robust against both the abundance revision and the opacity change: the ratio of the calculated to the SNO-measured $^{8}$B flux is 1.09 with the older abundances and 0.87 with the newer ones, within a 16% theoretical and 9% experimental uncertainty, and the p-p ratio is 0.99 to 1.00.
  • The agreement between two independently written stellar-evolution codes at the 0.01-0.4% level sets a benchmark: model-versus-observation discrepancies larger than that can no longer be waved away as code artifacts.
  • The updated $^{14}$N(p,$gamma$)$^{15}$O cross section roughly halves predicted $^{13}$N and $^{15}$O neutrino fluxes and lowers the CNO luminosity share to 0.8%, giving a sharp, testable signature for the next generation of solar neutrino experiments.

Reading between the lines

Editorial extensions of the paper, not claims the author makes directly.

  • The paper's negative conclusion about opacity rests on two libraries that are not fully independent: OP and OPAL draw on overlapping atomic data and similar line-broadening methods, so their agreement does not by itself bound the true opacity error at the 10% level.
  • A direct laboratory or spectroscopic determination of opacity in the 2 to 4.5 million kelvin regime — or an abundance reanalysis that pushes the metals back toward the older values — would decide between the two escape routes faster than further model grids.
  • Because the neutrino fluxes barely move between abundance choices while the sound-speed residuals move by a factor of three, the neutrino channel and the helioseismic channel are probing different physics; a joint fit to both could in principle discriminate an abundance error from an opacity error.
  • The cross-code agreement result suggests the remaining freedom in solar modeling lies in the input physics (opacities, equation of state, element diffusion) rather than in numerical implementation, which narrows where a resolution should be sought.
Original abstract

We construct solar models with the newly calculated radiative opacities from the Opacity Project (OP) and recently determined (lower) heavy element abundances. We compare results from the new models with predictions of a series of models that use OPAL radiative opacities, older determinations of the surface heavy element abundances, and refinements of nuclear reaction rates. For all the variations we consider, solar models that are constructed with the newer and lower heavy element abundances advocated by Asplund et al. (2005) disagree by much more than the estimated measuring errors with helioseismological determinations of the depth of the solar convective zone, the surface helium composition, the internal sound speeds, and the density profile. Using the new OP radiative opacities, the ratio of the 8B neutrino flux calculated with the older and larger heavy element abundances (or with the newer and lower heavy element abundances) to the total neutrino flux measured by the Sudbury Neutrino Observatory is 1.09 (0.87) with a 9% experimental uncertainty and a 16% theoretical uncertainty, 1 sigma errors.

The compiled record

The paper's own sentences, arranged, kept beside the review and separate from it. Each label is drawn from a closed vocabulary; the number beside it is the probability the classifier gave that label. Numbers in the tables are the authors', checked by code. No sentence in this record was written by a model.

Compiled by classifier-1.13.0 via TypeSafe API, question bank abstract-p1-20260923, 2026-09-23: 1 request, 3,951 input tokens.

What the abstract itself states, as probabilities: claims first 0.03 · states limitation 0.63 · human participants 0.02 · controlled comparison 0.78 · randomized assignment 0.01 · states quantitative result 0.98 · compares with prior results 0.98 · mentions code or data availability 0.02.

The abstract, sentence by sentence

arXiv listing abstract v3. Results and the main claim are underlined; .

We construct solar models with the newly calculated radiative opacities from the Opacity Project (OP) and recently determined (lower) heavy element abundances. We compare results from the new models with predictions of a series of models that use OPAL radiative opacities, older determinations of the surface heavy element abundances, and refinements of nuclear reaction rates. For all the variations we consider, solar models that are constructed with the newer and lower heavy element abundances advocated by Asplund et al. (2005) disagree by much more than the estimated measuring errors with helioseismological determinations of the depth of the solar convective zone, the surface helium composition, the internal sound speeds, and the density profile. Using the new OP radiative opacities, the ratio of the 8B neutrino flux calculated with the older and larger heavy element abundances (or with the newer and lower heavy element abundances) to the total neutrino flux measured by the Sudbury Neutrino Observatory is 1.09 (0.87) with a 9% experimental uncertainty and a 16% theoretical uncertainty, 1 sigma errors.

background contribution method result interpretation main claim

What the classifier reports for each sentence. The number is the probability it gave the label.
#sentencerolethe authors' own workstates the main conclusionstrength
s0 We construct solar models with the newly calculated radiative opacities from the Opacity Project (OP) and recently determined (lower) heavy element abundances. method 0.52 0.93 0.04 asserted 0.98
s1 We compare results from the new models with predictions of a series of models that use OPAL radiative opacities, older determinations of the surface heavy element abundances, and refinements of nuclear reaction rates. method 0.86 0.79 0.03 asserted 0.91
s2 For all the variations we consider, solar models that are constructed with the newer and lower heavy element abundances advocated by Asplund et al. (2005) disagree by much more than the estimated measuring errors with helioseismological determinations of the depth of the solar convective zone, the surface helium composition, the internal sound speeds, and the density profile. result 0.97 0.84 0.76 asserted 1.00
s3 Using the new OP radiative opacities, the ratio of the 8B neutrino flux calculated with the older and larger heavy element abundances (or with the newer and lower heavy element abundances) to the total neutrino flux measured by the Sudbury Neutrino Observatory is 1.09 (0.87) with a 9% experimental uncertainty and a 16% theoretical uncertainty, 1 sigma errors. result 1.00 0.81 0.12 asserted 1.00

What kind of paper the classifier reports this is: simulation study 0.95 · evidence from simulation or computation 0.98.

What was examined, and what was not

sources read
  • arXiv listing abstract v3
not examined
  • full text
  • figures and tables
  • references and citing sentences
  • relations to other papers
levels run
  • P abstract
not run
  • S sections
  • T body sentences
  • C citations
  • R cross-paper relations

Every quoted sentence on this record is the authors'. Every label is from Pith's closed vocabulary, with the probability shown beside it. Every number in the measurements table is the authors', checked by code. Record as JSON

Figures
Figure 1. — Relative sound speed differences, δc/c = (c⊙ −cmodel)/cmodel, and relative densities, δρ/ρ, between solar models and helioseismological results from MDI data
Figure 2. — Solar neutrino energy spectrum for the solar model B

Figures reproduced from arXiv:astro-ph/0412440 by the authors.

References
How later papers used it

132 later papers cite it

Evidence: substantial. 126 of the citing papers share no author with it, and 63 of those carry a confident label from Pith's citation classifier.

Pith read 28 of the 180 citing sentences, choosing only those whose citation markers point at this paper alone, and wrote the paraphrases from them. The summary, the counts, the evidence level, the links and the quotes come from code; the summary counts the papers listed below. A later paper is listed under a label when Pith's citation classifier gives one of its sentences that label at probability 0.8 or more (0.95 for support), Pith's reading finds that the citing paper itself did it, and a second check confirms the paraphrase against the sentence. This section lists uses only. It does not list criticism or disagreement, so their absence here says nothing about how the paper has been received. Papers that share an author with this one are listed apart, under "By the same authors". A quote is the citing authors' own sentence, shown when their paper's licence is CC BY, CC BY-SA or CC0. JSON

Uses its data or values 17 of 58 papers with this label
How the literature uses it

106 arXiv papers cite this in 148 sentences

Each citing sentence is taken from the citing paper's LaTeX source and typed by Pith's classifier. A label appears at probability 0.8 or more (0.95 for support), a contest at 0.7 or more; the quoted words are the citing authors'. How each label was checked · JSON

Papers whose main result relates to this one's

Found among the papers closest to this one by title and main claim. Pith's classifier compared each pair's main results and a second model family confirmed the relation; checked against two further families, shown conflicts agreed 118 times in 120 and shown same results 218 times in 239. The quoted sentence is the other paper's main claim.

States the same result 1 paper

Papers citing it · 74 sentences without a confident label

Uses its method or tool 3 papers
  • Using the results in Refs. [ref] , we performed a detailed numerical calculation by solving the Klein-Gordon equation with both $m^2ϕ^2$ and $ϕ^4$ terms and the Sun's density profile [ref] using the initial conditions $ϕ(∞)=0$ and $dϕ/dr|_r=0=0$.

    Sterile Neutrino Shape-shifting Caused by Dark Matter · Solar Neutrinos · 0.97

  • To incorporate the results from other experiments, the measured flux reported by an experiment assuming a flux of only electron neutrinos (i.e. $P_ee = 1$), $Φ_e$, is converted to an total inferred flux, $Φ_T$, by way of a neutrino model that predicts $P_ee$ and $P_ea$, the average survival probabilities for that flux, and the relative cross sections, $σ_a / σ_e$, where $σ_e$ is the cross section for electron-flavor neutrinos and $σ_a$ the cross section for all other neutrino flavors (i.e. $ν_μ$ and $ν_τ$) [equation] The neutrino decay model described in Section [ref] is used, and the averaging is done over the flux-appropriate standard solar model production regions (electron density) [ref] and experiment-appropriate cross section weighted neutrino spectra [ref] .

    Constraints on Neutrino Lifetime from the Sudbury Neutrino Observatory · Combined analysis results · 0.93

  • This calculation uses a hybrid model of the solar density profile based on [ref] , and the cascade equation solver [ref] to calculate the neutrino production from initial hadrons and secondary muons.

    Search for High-Energy Neutrinos From the Sun Using Ten Years of IceCube Data · Introduction · 0.92

Uses its data or values 50 papers
Compares with it 2 papers
Cites it as background 11 papers

Discussion

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