Polycyclic aromatic hydrocarbons in samples of Ryugu formed in the interstellar medium.
Sarah S ZeichnerJosé C AponteSurjyendu BhattacharjeeGuannan DongAmy E HofmannJason P DworkinDaniel P GlavinJamie E ElsilaHeather V GrahamHiroshi NaraokaYoshinori TakanoShogo TachibanaAllison Tyler KarpKliti GriceAlex I HolmanKatherine H FreemanHisayoshi YurimotoTomoki NakamuraTakaaki NoguchiRyuji OkazakiHikaru YabutaKanako SakamotoToru YadaMasahiro NishimuraAiko NakatoAkiko MiyazakiKasumi YogataMasanao AbeTatsuaki OkadaTomohiro UsuiMakoto YoshikawaTakanao SaikiSatoshi TanakaFuyuto TeruiSatoru NakazawaSei'ichiro WatanabeYuichi TsudaKenji HamaseKazuhiko FukushimaDan AokiMinako HashiguchiHajime MitaYoshihito ChikaraishiNaohiko OhkouchiNanako O OgawaSaburo SakaiEric T ParkerHannah L McLainFrancois-Regis Orthous-DaunayVéronique VuittonCédric WoltersPhilippe Schmitt-KopplinNorbert HertkornRoland ThissenAlexander RufJunko IsaYasuhiro ObaToshiki KogaToshihiro YoshimuraDaisuke AraokaHaruna SugaharaAogu FurushoYoshihiro FurukawaJunken AokiKuniyuki KanoShin-Ichiro M NomuraKazunori SasakiHajime SatoTakaaki YoshikawaSatoru TanakaMayu MoritaMorihiko OnoseFumie KabashimaKosuke FujishimaTomoya YamazakiYuki KimuraJohn M EilerPublished in: Science (New York, N.Y.) (2023)
Polycyclic aromatic hydrocarbons (PAHs) contain ≲20% of the carbon in the interstellar medium. They are potentially produced in circumstellar environments (at temperatures ≳1000 kelvin), by reactions within cold (~10 kelvin) interstellar clouds, or by processing of carbon-rich dust grains. We report isotopic properties of PAHs extracted from samples of the asteroid Ryugu and the meteorite Murchison. The doubly- 13 C substituted compositions (Δ2× 13 C values) of the PAHs naphthalene, fluoranthene, and pyrene are 9 to 51‰ higher than values expected for a stochastic distribution of isotopes. The Δ2× 13 C values are higher than expected if the PAHs formed in a circumstellar environment, but consistent with formation in the interstellar medium. By contrast, the PAHs phenanthrene and anthracene in Ryugu samples have Δ2× 13 C values consistent with formation by higher-temperature reactions.