المذنب بين النجمي: ماء أثقل من ماء الأرض بـ 14 مرة سريع

الملخص الأصلي

كما كتبه المؤلفون، بالإنجليزية arXiv:2603.20445

Interstellar objects are interlopers from other planetary systems, and their volatile compositions provide a glimpse into planet formation around their host star. We present near-infrared spectra of the coma of interstellar object 3I/ATLAS measured with the James Webb Space Telescope. Our results demonstrate an unexpectedly high $$\mathrm{D}/\mathrm{H} = (3.31\pm0.34)\%$$ for methane and represent an exceedingly rare detection of deuterated organic molecules in an interstellar object. This D/H ratio is a factor of $$14\pm2$$ higher than that measured in comet 67P/Churyumov-Gerasimenko by the Rosetta spacecraft, the only other comet for which CH$$_3$$D has been detected, yet the ratio of deuteration in methane compared with water is consistent for both comets within $$1.2\sigma$$. The D/H ratio in methane is observationally unconstrained in extrasolar sources to date, but the enriched ratio in 3I/ATLAS is most similar to those measured in other organic molecules toward primitive environments. The high D/H ratios of water and methane in 3I/ATLAS are a natural consequence of formation in a high D/H elemental ratio environment as a result of locally cold conditions in the protoplanetary disk and prior interstellar cloud. Thus, 3I/ATLAS formed in an environment very different from that in which our Sun and planets originated.