Overview
- ALMA’s Atacama Compact Array measured methanol-to-HCN production ratios of about 70 and 120, placing 3I/ATLAS among the most methanol-rich comets on record, surpassed only by anomalous C/2016 R2.
- High‑resolution maps show hydrogen cyanide emitted mainly from the nucleus, while methanol also escapes from sublimating icy grains in the coma, a first at this level of detail for an interstellar object.
- The findings, led by Nathan X. Roth of American University, are published in The Astrophysical Journal Letters and draw on late‑2025 submillimeter observations from Chile.
- The unusual chemistry and distinct outgassing behavior indicate the comet’s ices formed or were processed in environments that differ from those shaping most Solar System comets.
- 3I/ATLAS is the third confirmed interstellar visitor and is now outbound with a Jupiter pass approaching, as separate preprints report extreme isotopic ratios that suggest a cold and possibly very ancient origin.