P_E_T_E_R
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JWST hat das Methangas vom interstellaren Kometen 3I/ATLAS untersucht und dabei ein ungewöhnlich hohes D/H-Verhältnis von (3.18 +- 0.30)% gemessen. Das übersteigt den für Kometen im Sonnensystem typischen Wert (wie z.B. 67P/Churyumov–Gerasimenko) um einen Faktor von 13 +- 2. Daraus wird auf einen extrem kalten Entstehungsprozess für 3I/ATLAS geschlossen.
An enriched methane D/H ratio in the interstellar object 3I/ATLAS
Heavy hydrogen in 3I/ATLAS's methane points to a frigid birthplace
An enriched methane D/H ratio in the interstellar object 3I/ATLAS
Interstellar objects are interlopers from other planetary systems, and their volatile compositions provide a glimpse into planet formation around their host star. Here 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 D/H = (3.18 ± 0.30)% for methane and represent an exceedingly rare detection of deuterated organic molecules in an interstellar object. This D/H ratio exceeds any other value for methane measured in the Solar System and is a factor of 13 ± 2 higher than that measured in comet 67P/Churyumov–Gerasimenko by the Rosetta spacecraft, the only other comet for which CH3D has been detected. The elevated D/H ratio for methane in 3I/ATLAS is consistent with the hypothesis that its ices formed in a cold, low-metallicity interstellar or protostellar environment under a high cosmic ray irradiation rate.
Heavy hydrogen in 3I/ATLAS's methane points to a frigid birthplace
In extremely cold gas, some chemical reactions favor the incorporation of deuterium into molecules. At temperatures around 10 degrees above absolute zero, reactions that would undo that enrichment become less effective. Chemical reactions on interstellar dust grains can then build deuterium-rich ice that eventually becomes part of a comet.
Gruß, Peter