Refractory inclusions in Bennu samples indicative of outer Solar System accretion

KAWASAKI Noriyuki BAJO Ken-ichi

Department of Earth and Planetary Sciences

Jul. 23, 2026

小惑星「ベヌー」から見つかった難揮発性包有物の例。そのうち一つ（左）は、太陽系誕生直後の約45億6,730万年前に形成されたことが判明。データはMg(赤)―Ca(緑)―Al(青)の合成X線元素マップ。スケールバーは0.01ミリメートル。（©Kawasaki et al. 2026）

Press release (in Japanese)

Abstract
NASA’s OSIRIS-REx mission returned material from the carbonaceous asteroid Bennu, which is dominated by aqueous-alteration products but preserves rare high-temperature components. Here we present an integrated petrographic, oxygen-isotopic and ²⁶Al–²⁶Mg chronological characterization of refractory inclusions in Bennu samples. All identified inclusions are small (<~100 µm) and commonly preserve mineralogical evidence of in situ aqueous alteration, indicating incorporation into Bennu’s parent body prior to hydration. Their mineralogical characteristics and oxygen-isotopic and ²⁶Al–²⁶Mg systematics demonstrate formation during the earliest stage of Solar System evolution and genetic affinity with refractory inclusions in asteroid Ryugu samples and chondritic meteorites. The shared refractory-inclusion signatures across diverse chondritic materials are consistent ……

Read the original article on Nature Communications

Article inforamation
Kawasaki, N., Matsumoto, T., Arakawa, S. et al. Refractory inclusions in Bennu samples indicative of outer Solar System accretion. Nat Commun (2026). https://doi.org/10.1038/s41467-026-73868-6