Overview
- The study published Monday, June 22 in Nature combines JWST NIRSpec data with ALMA and VLT spectra to deliver the first high‑fidelity isotopic readout of an interstellar object.
- JWST measured water extremely enriched in deuterium at roughly 30 times the level seen in Solar System comets, a signature that indicates formation at very low temperatures.
- Spectra show only trace amounts of carbon‑13 relative to carbon‑12, a pattern consistent with formation before repeated stellar generations enriched the galaxy with heavier isotopes.
- 3I/ATLAS was unusually large and bright for an interstellar visitor, which let teams seize a narrow post‑perihelion window to obtain these measurements while the object was active and is now on a hyperbolic path leaving the Solar System.
- Researchers say the findings give a direct sample of early Milky Way chemistry that will test models of planetesimal formation and the spread of prebiotic ingredients, while noting age and origin inferences depend on chemical and astrophysical models and more interstellar samples are needed.