2025/03/19 by O. Mousis, Aaron Werlen, Mousis, Olivier +5 · 2 citations
Physics and Astronomy · #Astro and Planetary Science #Earth and Planetary Astrophysics (astro-ph.EP) #FOS: Physical sciences
paper · pdf · doi:10.48550/arxiv.2503.15652
openalex publication_date 2025/03/19 · openalex created_date 2025/10/17 · openalex updated_date 2026/07/28
Deuterium, a heavy isotope of hydrogen, is a key tracer of the formation of the Solar System. Recent JWST observations have expanded the dataset of D/H ratios in methane on the KBOs Eris and Makemake, providing new insights into their origins. This study examines the elevated D/H ratios in methane on these KBOs in the context of protosolar nebula dynamics and chemistry, and proposes a primordial origin for the methane, in contrast to previous hypotheses suggesting abiotic production by internal heating. A time-dependent disk model coupled with a deuterium chemistry module was used to simulate the isotopic exchange between methane and hydrogen. Observational constraints, including the D/H ratio measured in methane in comet 67P/Churyumov-Gerasimenko, were used to refine the primordial D/H abundance. The simulations show that the observed D/H ratios in methane on Eris and Makemake are consistent with a primordial origin. The results suggest that methane on these KBOs likely originates from the protosolar nebula, similar to cometary methane, and was sequestered in solid form -- either as pure condensates or clathrates -- within their building blocks prior to accretion. These results provide a simple explanation for the high D/H ratios in methane on Eris and Makemake, without the need to invoke internal production mechanisms.