Evidence of both molecular cloud and fluid chemistry in Ryugu regolith.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 39047107.
- Also identified by DOI 10.1126/sciadv.adp3037 and PMC identifier 11268420.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
The sulfur chemistry of (162173) Ryugu particles can be a powerful tracer of molecular cloud chemistry and small body processes, but it has not been well explored. We report identification of organosulfurs and a sulfate grain in two Ryugu particles, A0070 and A0093. The sulfate grain shows oxygen isotope ratios (δ<sup>17</sup>O = -11.0 ± 4.3 per mil, δ<sup>18</sup>O = -7.8 ± 2.3 per mil) that are akin to silicates in Ryugu but exhibit mass-independent sulfur isotopic fractionation (Δ<sup>33</sup>S = +5 ± 2 per mil). A methionine-like coating on the sulfate grain is isotopically anomalous (δ<sup>15</sup>N = +62 ± 2 per mil). Both the sulfate and organosulfurs can simultaneously form and survive during aqueous alteration within Ryugu's parent body, under reduced conditions, low temperature, and a pH >7 in the presence of N-rich organic molecules. This work extends the heliocentric zone where anomalous sulfur, formed by selective photodissociation of H<sub>2</sub>S gas in the molecular cloud, is found.