Papers · William Alexander Aldred

The Sun Won't Confess: Three Probes, Two Compositions, No Closure

Publicly deposited November 1, 2026 · Zenodo · 5 pp · DOI: 10.5281/zenodo.23865470

Abstract

The solar abundance problem is a defect with three independent witnesses. Standard solar models built on the modern spectroscopic composition (low metallicity, AGSS09) fail the helioseismic observables: convection-zone depth R_CZ = 0.7223 ± 0.0053 against the seismic 0.713 ± 0.001 (defect +1.7σ with model errors charged whole; +9σ if they are not), surface helium Y_S = 0.2317 ± 0.0059 against 0.2485 ± 0.0035 (−2.4σ), and a sound-speed profile with a localized discrepancy of order 1% below the convection zone. Models built on the older composition (high metallicity, GS98) pass every seismic observable (R_CZ defect −0.29σ, Y_S −0.86σ, sound speed flat at a few parts in 10³) — but the photospheric spectroscopy that produced the low composition is direct measurement, not a model preference, and it has only strengthened with 3D non-LTE technique. The third witness, neutrinos, leans toward the high composition: Borexino's final CNO flux, Φ_CNO = 6.7 (+1.2/−0.8)×10⁸ cm⁻² s⁻¹, combined with its ⁷Be and ⁸B fluxes, disfavors the low-metallicity B16 model at 3.2σ — yet the measured CNO flux sits above both compositions' predictions, and the prediction itself moved ~15% in 2025 when the CNO cycle's slowest reaction, ¹⁴N(p,γ)¹⁵O, was remeasured upward. A different recent model generation flips the ⁸B preference to the low composition entirely. Verdict: the solar core is not closed. Helioseismology convicts the spectroscopic composition; spectroscopy refuses to recant; neutrinos lean with seismology but cannot yet testify at the precision the case requires, because their key prediction is a nuclear cross-section that is still being re-measured. The cheapest exits are priced in §4 — an opacity revision at the convection-zone base, the nuclear-rate settlement, and surface–core decoupling by early accretion — and none is endorsed. The best-measured star in the sky keeps its secret, and this paper's business is the size of the lock, not a story about the key. ---

The result, in plain language

The Sun's core composition is a case with three independent witnesses, and they do not agree. Helioseismology convicts the modern low-metallicity composition: its models miss the convection-zone depth and the surface helium at +1.7σ and +2.4σ, with a sound-speed discrepancy of order 1% — while the older high-metallicity composition passes every seismic observable. But the spectroscopy behind the low composition is direct measurement, and it refuses to recant.

The third witness, neutrinos, leans toward the high composition — Borexino's CNO flux disfavors the low-metallicity model at 3.2σ — yet neutrinos cannot yet testify at the precision the case requires: their key prediction is the ¹⁴N(p,γ)¹⁵O rate, remeasured in 2025, moving the CNO prediction ~15% after the measurement. Verdict: not closed. The cheapest exits are priced in §4 — an opacity revision, the nuclear-rate settlement, surface–core decoupling — and none is endorsed. This paper's business is the size of the lock, not a story about the key.

Program note

Cube Campaign Batch 2, target C-14. The solar core priced as a three-witness defect; every input checked against the published record during the run. Verdict, as the paper states it: not closed — a three-way standoff, priced. Helioseismology convicts the low-metallicity composition (+1.72σ, +2.45σ) while the high-metallicity model passes; Borexino's CNO flux leans to the high-metallicity side at 3.2σ; and a 2025 remeasurement of the ¹⁴N(p,γ) rate moved the CNO prediction 15% after the measurement. Three doors are named; none is endorsed. The vacuum catastrophe remains unsolved, and this paper claims no result on it.

The program