Abundant presolar grains and primordial organics preserved in carbon-rich exogenous clasts in asteroid Ryugu.
Ann N NguyenPrajkta ManeLindsay P KellerLaurette PianiYoshinari AbeJérôme AléonConel M O'D AlexanderSachiko AmariYuri AmelinKen-Ichi BajoMartin BizzarroAudrey BouvierRichard W CarlsonMarc ChaussidonByeon-Gak ChoiNicolas DauphasAndrew M DavisTommaso Di RoccoWataru FujiyaRyohta FukaiIkshu GautamMakiko K HabaYuki HibiyaHiroshi HidakaHisashi HommaPeter HoppeGary R HussKiyohiro IchidaTsuyoshi IizukaTrevor R IrelandAkira IshikawaShoichi ItohNoriyuki KawasakiNoriko T KitaKouki KitajimaThorsten KleineShintaro KomataniAlexander N KrotMing-Chang LiuYuki MasudaKevin D McKeeganMayu MoritaKazuko MotomuraFrederic MoynierIzumi NakaiKazuhide NagashimaDavid NesvornýLarry R NittlerMorihiko OnoseAndreas PackChangkun ParkLiping QinSara S RussellNaoya SakamotoMaria SchönbächlerLauren TaflaHaolan TangKentaro TeradaYasuko TeradaTomohiro UsuiSohei WadaMeenakshi WadhwaRichard J WalkerKatsuyuki YamashitaQing-Zhu YinTetsuya YokoyamaShigekazu YonedaEdward D YoungHiroharu YuiAi-Cheng ZhangTomoki NakamuraHiroshi NaraokaTakaaki NoguchiRyuji OkazakiKanako SakamotoHikaru YabutaMasanao AbeAkiko MiyazakiAiko NakatoMasahiro NishimuraTatsuaki OkadaToru YadaKasumi YogataSatoru NakazawaTakanao SaikiSatoshi TanakaFuyuto TeruiYuichi TsudaSei'ichiro WatanabeMakoto YoshikawaShogo TachibanaHisayoshi YurimotoPublished in: Science advances (2023)
Preliminary analyses of asteroid Ryugu samples show kinship to aqueously altered CI (Ivuna-type) chondrites, suggesting similar origins. We report identification of C-rich, particularly primitive clasts in Ryugu samples that contain preserved presolar silicate grains and exceptional abundances of presolar SiC and isotopically anomalous organic matter. The high presolar silicate abundance (104 ppm) indicates that the clast escaped extensive alteration. The 5 to 10 times higher abundances of presolar SiC (~235 ppm), N-rich organic matter, organics with N isotopic anomalies (1.2%), and organics with C isotopic anomalies (0.2%) in the primitive clasts compared to bulk Ryugu suggest that the clasts formed in a unique part of the protoplanetary disk enriched in presolar materials. These clasts likely represent previously unsampled outer solar system material that accreted onto Ryugu after aqueous alteration ceased, consistent with Ryugu's rubble pile origin.