![\"Characterization](\"https:\/\/cdn.sci.news\/images\/enlarge13\/image_14413e-Bennu-Stardust.jpg\")
<\/a><\/p>\nCharacterization of a presolar spinel-hibonite grain from the asteroid Bennu. Image credit: Nguyen et al., doi: 10.1038\/s41550-025-02688-3.<\/p>\n
\u201cPresolar stardust grains are found at trace levels in meteorites, interplanetary dust particles, Antarctic meteorites, the samples from the comet 81\u2009P\/Wild2 returned by NASA\u2019s Stardust mission, and the carbonaceous asteroid Ryugu samples returned by JAXA\u2019s Hayabusa-2 mission,\u201d said Dr. Ann Nguyen from NASA\u2019s Johnson Space Center and colleagues.<\/p>\n
\u201cTheir highly anomalous isotopic compositions result from nucleosynthetic reactions in evolved red giant stars, supernovae and novae.\u201d<\/p>\n
\u201cThe mineralogy and chemistry of presolar grains can be used to constrain condensation conditions and to probe the effects of secondary alteration, as these grains are susceptible to alteration or destruction in space, in the Solar Nebula and within planetesimals.\u201d<\/p>\n
In the study, the scientists analyzed presolar grains found in two different rock types in the Bennu samples.<\/p>\n
The samples had six-times the amount of the grains than any other studied astromaterial, suggesting the asteroid\u2019s parent body formed in a region of the protoplanetary disk enriched in the dust of dying stars.<\/p>\n
The study also reveals that, while Bennu\u2019s parent asteroid experienced extensive alteration by fluids, there are still pockets of less-altered materials within the samples that offer insights into its origin.<\/p>\n
\u201cThese fragments retain a higher abundance of organic matter and presolar silicate grains, which are known to be easily destroyed by aqueous alteration in asteroids,\u201d Dr. Nguyen said.<\/p>\n
\u201cTheir preservation in the Bennu samples was a surprise and illustrates that some material escaped alteration in the parent body.\u201d<\/p>\n
\u201cOur study reveals the diversity of presolar materials that the parent accreted as it was forming.\u201d<\/p>\n