The isotopic composition of oxygen in the solar system finally explained
A multidisciplinary team of French and British researchers—affiliated with the Institut de physique du globe de Paris (Université Paris Cité/IPGP/CNRS), the Institut de minéralogie, de physique des matériaux et de cosmochimie (Muséum national d’histoire naturelle/Sorbonne Université/CNRS), the Laboratoire des sciences des procédés et des matériaux (Université Sorbonne Paris Nord/CNRS), the Centre de recherches pétrographiques et géochimiques (CNRS/Université de Lorraine), and the Department of Earth and Environmental Sciences (University of Manchester)—has published a study in the journal Proceedings of the National Academy of Sciences that sheds new light on one of the major mysteries surrounding the formation of the solar system: the isotopic composition of oxygen.
Condensates of organic matter produced during experiment 77c. The darker region shows one of the oxygen isotopic composition analyses / @IPGP
Publication date: 05/05/2025
Events, Press, Research
Related teams :
Cosmochemistry, Astrophysics and Experimental Geophysics (CAGE)
Why do all solids formed in the solar system have isotopic compositions so different from that of the primordial gas (the protosolar nebula) represented by the sun?
Since the 1970s, scientists have puzzled over the stark differences between the oxygen isotopic composition of terrestrial planets, asteroids, and comets, and that of the sun—determined with high precision through the analysis of solar wind returned to Earth by NASA’s Genesis mission.
In the 1980s, the discovery that ozone formation in Earth’s upper atmosphere generates isotopic variations similar to those observed in meteorites led to the hypothesis that analogous reactions might have occurred in the protosolar nebula. However, no theoretical model or laboratory experiment had been able to confirm this hypothesis.
To resolve this mystery, the researchers experimentally reproduced the condensation of solids within a plasma mimicking the protosolar nebula in terms of chemical composition (methane and water vapor), pressure, and ionization rate. Their results show for the first time that solids condensed at high temperatures in such a plasma exhibit oxygen isotopic variations characteristic of terrestrial planets and small bodies in the solar system. The experiments suggest these variations stem from a reaction involving a short-lived activated complex, H₂O₂*, within the plasma. While this reaction alone cannot account for all observed isotopic variations, other activated complexes such as SiO₂* or CO₂* may also play a key role.
These discoveries pave the way for reconstructing the chain of reactions that led to the formation of the first solids in the solar system—an objective that had remained out of reach until now.
Source
Mass-independent fractionation of oxygen isotopes during high-temperature condensation in cosmochemical plasmas
DOI : https://doi.org/10.1073/pnas.2426711122
Contacts :
IPGP : Pierre-Yves Clausse I I + 33 (0)6 51 67 84 83
CNRS : Bureau de presse I I +33 (0)1 44 96 51 51
