Content Quality: Well-structured News-category piece (725 words, within the 400-1200 range) using the site's Overview / What We Know / What We Don't Know / Background convention. Prose is clear, appropriately technical for an astrophysics detection story, and every paragraph carries an inline citation to one of the four sources.
Source Verification: All four cited URLs verified. (1) https://www.eso.org/public/news/eso2611/ — snapshot sources/2026-07/astronomers-capture-clearest-ever-image-of-betelgeuses-elusive-companion-star/source-0.html.gz (200 OK, sha256 a6480a9a...eab873 re-computed and matches manifest). Read in full; confirms the headline finding, both Montargès quotes ('This is the conclusion of a century-long quest' / 'We have shown that Betelgeuse is not single...'), the Boccaletti quote, the century-long search, the 2024 predicted-elongation studies, the ~2-3 solar mass finding, the dimming/dust-cloud background, and the 'truly opened' impact-on-evolution quote verbatim. (2) https://www.space.com/astronomy/... — snapshot source-1.html.gz (200 OK, sha256 b3c5c558...02af833 re-computed and matches manifest). Read in full; confirms the 'century-long quest' quote and Montargès's team-leader/Observatoire de Paris affiliation, the 'Because it is more massive than predicted, we see it!' quote, and the Boccaletti SPHERE/post-processing quote verbatim. Also surfaced two discrepancies the contributor bot correctly avoided: (a) Space.com states SPHERE 'features a coronagraph that blocks out the light of a planetary system's star' — the primary paper's Appendix C explicitly states 'the 2024 observations were obtained without a coronagraphic mask,' so this Space.com claim is contradicted by the primary source for this specific observation; the article contains no mention of a coronagraph, confirming the bot's stated exclusion held. (b) Space.com describes Betelgeuse's earlier well-known episode as 'sudden and rapid brightening,' which conflicts with the established 'Great Dimming' event and with ESO's own snapshot ('it visibly started dimming'); the article's Background section cites ESO (not Space.com) for the dimming claim, correctly sidestepping the Space.com error. (3) https://www.eso.org/public/archives/releases/sciencepapers/eso2611/eso2611a.pdf — the archived snapshot (source-2.html.gz) decompresses to a byte-perfect match of its own manifest sha256, but the underlying PDF is corrupted: it contains 368,708 occurrences of the UTF-8 replacement-character byte sequence (EF BF BD) spread across the 1.64MB file, consistent with the original binary response having been decoded as UTF-8 text (replacing invalid byte sequences) before being saved/gzipped — this destroys the PDF's xref/object-stream structure and makes it unparseable (pdftotext: 'Illegal character', 'Couldn't find trailer dictionary'). Since this is a genuine content-loss failure masked by a passing hash check (the hash just confirms the corrupted bytes were saved consistently), I re-fetched the PDF live via curl (916KB, valid PDF 1.5, cleanly parsed with pdftotext) as the mandated fallback. The live paper confirms, verbatim/numerically: 6.1σ (PACO ASDI) and 5.1σ (PCA) detections in the CntHa filter; CntHa centered at 644.9nm, NHa centered at 656.34nm with no secondary source; separation ρ=52.32±0.18 mas at PA=117.12±0.60°; companion mass 2.6-3.1 M☉, spectral type B8.5V-B9.5V; Gemini North 'Alopeke 1.5σ tentative signal; primary mass 16.5-19 M☉ implying orbital period (5.9-5.5) yr, consistent with Goldberg et al. 2024 (5.94 yr) and MacLeod et al. 2025 (5.78 yr); LSP of 2200 days (~6.02 yr). Every specific number in the article's 'What We Know' section traces exactly to this paper. (4) https://phys.org/news/2026-07-astronomers-strongest-evidence-betelgeuse-companion.html — snapshot failed (manifest: file=null, status_code=403, error='Forbidden', bot-blocked). Per protocol, fell back to a live WebFetch of the URL, which returned a July 28, 2026 phys.org piece (an ESO press-release syndication) confirming: 'The potential detection of Betelgeuse B will prompt astronomers to investigate how the companion could affect Betelgeuse's anticipated supernova explosion' — a faithful paraphrase of the article's closing sentence citing Phys.org. This is explicitly noted as a live-fallback verification, not a snapshot read.
Factual Accuracy: No hallucinated or fabricated specifics found. Every direct quote appears verbatim in its cited snapshot. Every numeric specific (sigma values, wavelengths, separation, position angle, mass range, spectral type, orbital period figures, LSP period) traces exactly to the primary paper. The one minor sourcing nuance: the clause 'an astronomer at the Observatoire de Paris - PSL, France' is folded into the sentence cited to Space.com, but Space.com's own text only says 'of the Observatoire de Paris, France' (no '- PSL'); the fuller affiliation appears in the adjacently-cited ESO snapshot instead. The fact itself is correct and is cited elsewhere in the same paragraph, so this reads as a minor citation-merge stylistic issue rather than a factual error — it does not misinform the reader and does not warrant a public correction.
Overall Assessment: High-quality, accurate submission. Every quote and every specific figure was independently verified against the primary paper (re-fetched live after the archived snapshot proved corrupted) and against the ESO and Space.com snapshots. The contributor bot's decision to exclude the Space.com 'coronagraph' claim was correct and independently confirmed against the paper's Appendix C. No fabrications, no misattributions material enough to require a corrections record. Approved without corrections; the phys.org archival gap and PDF snapshot corruption are pipeline/technical notes, not content-quality issues.