2022-06-09 ワシントン大学セントルイス
研究チームは、リュウグウから戻ってきたサンプルと、地球で発見された最も原始的な炭素質隕石と考えられているCIコンドライトと呼ばれる種類の隕石との類似性を説明しました。その結果、CIコンドライトは地球上で変質したものであり、リュウグウのサンプルは地球上の汚染や変質がないため、CIコンドライトよりも原始的なものであることを示しました。このことは、リュウグウのサンプルには、初期太陽系を理解する上で、これまで得られなかった情報が含まれている可能性を示唆しています。
＜関連情報＞
- https://source.wustl.edu/2022/06/asteroid-samples-offer-chance-to-study-chemically-pristine-solar-system-materials/
- https://www.science.org/doi/10.1126/science.abn7850
小惑星リュウグウのサンプルはイブナ型炭素質隕石に類似していることが判明 Samples returned from the asteroid Ryugu are similar to Ivuna-type carbonaceous meteorites
Tetsuya Yokoyama,Kazuhide Nagashima,Izumi Nakai,Edward D. Young,Yoshinari Abe,Jérôme Aléon,Conel M. O’D. Alexander,Sachiko Amari,Yuri Amelin,Ken-ichi Bajo,Martin Bizzarro,Audrey Bouvier,Richard W. Carlson,Marc Chaussidon,Byeon-Gak Choi,Nicolas Dauphas,Andrew M. Davis,Tommaso Di Rocco,Wataru Fujiya,Ryota Fukai,Ikshu Gautam,Makiko K. Haba,Yuki Hibiya,Hiroshi Hidaka,Hisashi Homma,Peter Hoppe,Gary R. Huss,Kiyohiro Ichida,Tsuyoshi Iizuka,Trevor R. Ireland,Akira Ishikawa,Motoo Ito,Shoichi Itoh,Noriyuki Kawasaki,Noriko T. Kita,Kouki Kitajima,Thorsten Kleine,Shintaro Komatani,Alexander N. Krot,Ming-Chang Liu,Yuki Masuda,Kevin D. McKeegan,Mayu Morita,Kazuko Motomura,Frédéric Moynier,Ann Nguyen,Larry Nittler,Morihiko Onose,Andreas Pack,Changkun Park,Laurette Piani,Liping Qin,Sara S. Russell,Naoya Sakamoto,Maria Schönbächler,Lauren Tafla,Haolan Tang,Kentaro Terada,Yasuko Terada,Tomohiro Usui,Sohei Wada,Meenakshi Wadhwa,Richard J. Walker,Katsuyuki Yamashita,Qing-Zhu Yin,Shigekazu Yoneda,Hiroharu Yui,Ai-Cheng Zhang,Harold C. ConnollyJr.,Dante S. Lauretta,Tomoki Nakamura,Hiroshi Naraoka,Takaaki Noguchi,Ryuji Okazaki,Kanako Sakamoto,Hikaru Yabuta,Masanao Abe,Masahiko Arakawa,Atsushi Fujii,Masahiko Hayakawa,Naoyuki Hirata,Naru Hirata,Rie Honda,Chikatoshi Honda,Satoshi Hosoda,Yu-ichi Iijima,Hitoshi Ikeda,Masateru Ishiguro,Yoshiaki Ishihara,Takahiro Iwata,Kosuke Kawahara,Shota Kikuchi,Kohei Kitazato,Koji Matsumoto,Moe Matsuoka,Tatsuhiro Michikami,Yuya Mimasu,Akira Miura,Tomokatsu Morota,Satoru Nakazawa,Noriyuki Namiki,Hirotomo Noda,Rina Noguchi,Naoko Ogawa,Kazunori Ogawa,Tatsuaki Okada,Chisato Okamoto,Go Ono,Masanobu Ozaki,Takanao Saiki,Naoya Sakatani,Hirotaka Sawada,Hiroki Senshu,Yuri Shimaki,Kei Shirai,Seiji Sugita,Yuto Takei,Hiroshi Takeuchi,Satoshi Tanaka,Eri Tatsumi,Fuyuto Terui,Yuichi Tsuda,Ryudo Tsukizaki,Koji Wada,Sei-ichiro Watanabe,Manabu Yamada,Tetsuya Yamada,Yukio Yamamoto,Hajime Yano,Yasuhiro Yokota,Keisuke Yoshihara,Makoto Yoshikawa,Kent Yoshikawa,Shizuho Furuya,Kentaro Hatakeda,Tasuku Hayashi,Yuya Hitomi,Kazuya Kumagai,Akiko Miyazaki,Aiko Nakato,Masahiro Nishimura,Hiromichi Soejima,Ayako Suzuki,Toru Yada,Daiki Yamamoto,Kasumi Yogata,Miwa Yoshitake,Shogo Tachibana,Hisayoshi Yurimoto
Science Published:9 Jun 2022
DOI:DOI: 10.1126/science.abn7850
Abstract
Carbonaceous meteorites are thought to be fragments of C-type (carbonaceous) asteroids. Samples of the C-type asteroid (162173) Ryugu were retrieved by the Hayabusa2 spacecraft. We measure the mineralogy, bulk chemical and isotopic compositions of Ryugu samples. They are mainly composed of materials similar to carbonaceous chondrite meteorites, particularly the CI (Ivuna-type) group. The samples consist predominantly of minerals formed in aqueous fluid on a parent planetesimal. The primary minerals were altered by fluids at a temperature of 37 ± 10°C,
of the first solids in the Solar System. After aqueous alteration,the Ryugu samples were likely never heated above ~100°C. The samples have a chemical composition that more closely resembles the Sun’s photosphere than other natural samples do.
