Overview
- Papers published in Nature on June 22 report coordinated JWST NIRSpec, ALMA and VLT observations that measured isotopes in 3I/ATLAS’s gas coma.
- JWST detected exceptionally high deuterium levels—about 30 times those in solar-system comets—consistent with ices that formed at very low temperatures near 30 K.
- Ground-based spectra showed only traces of carbon-13 relative to carbon-12, a pattern that, when combined with chemical-evolution models, yields the team’s 10–12 billion year formation estimate but carries model-dependent uncertainty.
- 3I/ATLAS is the third confirmed interstellar object and was unusually large and bright, with a strong post-perihelion coma in December 2025 that enabled the high-fidelity isotopic measurements.
- Authors say the result gives a direct data point on early Milky Way chemistry and possible prebiotic conditions, while emphasizing that broader conclusions will need further analysis and more interstellar samples.