Polycyclic aromatic hydrocarbons in samples of Ryugu formed in the interstellar medium
Sarah S. Zeichner, José C. Aponte, Surjyendu Bhattacharjee, Guannan Dong, Amy E. Hofmann, Jason P. Dworkin, Daniel P. Glavin, Jamie E. Elsila, Heather V. Graham, Hiroshi Naraoka, Yoshinori Takano, Shogo Tachibana, Allison T. Karp, Kliti Grice, Alex I. Holman, Katherine H. Freeman, Hisayoshi Yurimoto, Tomoki Nakamura, Takaaki Noguchi, Ryuji Okazaki, Hikaru Yabuta, Kanako Sakamoto, Toru Yada, Masahiro Nishimura, Aiko Nakato, Akiko Miyazaki, Kasumi Yogata, Masanao Abe, Tatsuaki Okada, Tomohiro Usui, Makoto Yoshikawa, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Satoru Nakazawa, Sei-ichiro Watanabe, Yuichi Tsuda, Kenji Hamase, Kazuhiko Fukushima, Dan Aoki, Minako Hashiguchi, Hajime Mita, Yoshito Chikaraishi, Naohiko Ohkouchi, Nanako O. Ogawa, Saburo Sakai, Eric T. Parker, Hannah L. McLain, Francois-Regis Orthous-Daunay, Véronique Vuitton, Cédric Wolters, Philippe Schmitt-Kopplin, Norbert Hertkorn, Roland Thissen, Alexander Ruf, Junko Isa, Yasuhiro Oba, Toshiki Koga, Toshihiro Yoshimura, Daisuke Araoka, Haruna Sugahara, Aogu Furusho, Yoshihiro Furukawa, Junken Aoki, Kuniyuki Kano, Shin-ichiro M. Nomura, Kazunori Sasaki, Hajime Sato, Takaaki Yoshikawa, Satoru Tanaka, Mayu Morita, Morihiko Onose, Fumie Kabashima, Kosuke Fujishima, Tomoya Yamazaki, Yuki Kimura, John M. Eiler
Science
21 Dec 2023, Vol 382, Issue 6677, pp. 1411-1416
“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 (~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-13C substituted compositions (Δ2×13C values) of the PAHs naphthalene, fluoranthene, and pyrene are 9 to 51‰ higher than values expected for a stochastic distribution of isotopes. The Δ2×13C 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 Δ2×13C values consistent with formation by higher-temperature reactions.”
