Summary
A team led by cyrielle-opitom (University of Edinburgh), with Jean Manfroid and Damien Hutsemékers (University of Liège), used the UVES instrument on ESO’s Very Large Telescope to measure both carbon and nitrogen isotope ratios in cyanide (CN) gas around interstellar comet 3i-atlas — the first such dual-isotope measurement for any interstellar object, enabled by 3I/ATLAS’s unprecedented brightness relative to 1I/ʻOumuamua and 2I/Borisov. The study, published in Nature Astronomy, finds “unusually high” carbon and nitrogen isotopic ratios, indicating 3I/ATLAS formed in the outer regions of an old, low-metallicity star system — consistent with the galactic-thick-disk framing from the Oxford orbital study (src-3i-atlas-oxford-age-2026-06). The article frames this as corroborating martin-cordiner’s JWST NIRSpec paper (src-3i-atlas-jwst-isotopic-age-2026-06, src-3i-atlas-nasa-webb-ancient-2026-06), which found a “similar isotopic ratio of carbon” plus elevated deuterium, and states the combined evidence points to 3I/ATLAS being “more than twice as old as the Sun” — a figure that sits between, and does not fully resolve, the existing ~7 Gyr (Oxford, orbital) vs. ~12 Gyr (JWST, isotopic) discrepancy already tracked in the vault. Note a possible framing wrinkle: this ESO release describes “unusually high” carbon isotopic ratios, while the JWST/Cordiner Nature paper describes an unusually low ¹³C/¹²C ratio — likely the same underlying measurement expressed via inverse ratio conventions, but not explicitly reconciled in either source. A footnote also credits a separate ALMA-based team with measuring elevated deuterated water, which may duplicate or supplement the University of Michigan-led D/H finding in src-3i-atlas-heavy-water-2026-05.
Key Claims
- VLT/UVES measured carbon and nitrogen isotope ratios in cometary CN gas — the first such measurement for an interstellar object (Opitom et al.).
- 3I/ATLAS shows “unusually high carbon and nitrogen isotopic ratios” vs. Solar System comets.
- Findings indicate formation in the outskirts of an old, low-metallicity star system, predating the Sun.
- Cordiner’s JWST Nature study found a similar carbon isotopic signature plus elevated deuterium — cited as independent corroboration.
- A separate ALMA study found elevated deuterated (“semi-heavy”) water in 3I/ATLAS.
- Combined evidence from multiple teams suggests 3I/ATLAS is “more than twice as old as the Sun.”
- ESO’s forthcoming Extremely Large Telescope (ELT) will extend this isotopic technique to future, fainter interstellar objects.
Notable Quotes
“They are sort of fossils from a planetary formation process that happened very far away, but that we get the chance to study from much closer.” — Cyrielle Opitom
“Unlike comets from our Solar System, this interstellar visitor carries unusually high carbon and nitrogen isotopic ratios.” — Aravind Krishnakumar
“3I/ATLAS is a really exciting opportunity to probe the composition of another planetary system, one that formed long before our Sun and Solar System even existed.” — Rosemary Dorsey