Neodymium-142 deficits and samarium neutron stratigraphy of C-type asteroid (162173) Ryugu

Research output: Contribution to journalJournal articleResearchpeer-review

  • Zachary A. Torrano
  • Michelle K. Jordan
  • Timothy D. Mock
  • Richard W. Carlson
  • Ikshu Gautam
  • Makiko K. Haba
  • Tetsuya Yokoyama
  • Yoshinari Abe
  • Jérôme Aléon
  • Conel Alexander
  • Sachiko Amari
  • Yuri Amelin
  • Ken-ichi Bajo
  • Audrey Bouvier
  • Marc Chaussidon
  • Byeon-Gak Choi
  • Nicolas Dauphas
  • Andrew M. Davis
  • Tommaso Di Rocco
  • Wataru Fujiya
  • Ryota Fukai
  • Yuki Hibiya
  • Hiroshi Hidaka
  • Hisashi Homma
  • Peter Hoppe
  • Gary R. Huss
  • Kiyohiro Ichida
  • Tsuyoshi Iizuka
  • Trevor Ireland
  • Akira Ishikawa
  • Shoichi Itoh
  • Noriyuki Kawasaki
  • Noriko T. Kita
  • Koki Kitajima
  • Thorsten Kleine
  • Shintaro Komatani
  • Alexander N. Krot
  • Ming-Chang Liu
  • Yuki Masuda
  • Kevin D. McKeegan
  • Mayu Morita
  • Kazuko Motomura
  • Frédéric Moynier
  • Izumi Nakai
  • Kazuhide Nagashima
  • Ann Nguyen
  • Larry Nittler
  • Morihiko Onose
  • Andreas Pack
  • Changkun Park
  • Laurette Piani
  • Liping Qin
  • Sara 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
  • Edward D. Young
  • Hiroharu Yui
  • Ai-Cheng Zhang
  • Tomoki Nakamura
  • Hiroshi Naraoka
  • Takaaki Noguchi
  • Ryuji Okazaki
  • Kanako Sakamoto
  • Hikaru Yabuta
  • Masanao Abe
  • Akiko Miyazaki
  • Aiko Nakato
  • Masahiro Nishimura
  • Tatsuaki Okada
  • Toru Yada
  • Kasumi Yogata
  • Satoru Nakazawa
  • Takanao Saiki
  • Satoshi Tanaka
  • Fuyuto Terui
  • Yuichi Tsuda
  • Sei-ichiro Watanabe
  • Makoto Yoshikawa
  • Shogo Tachibana
  • Hisayoshi Yurimoto

We report Nd and Sm isotopic compositions of four samples of Ryugu returned by the Hayabusa2 mission, including “A” (first touchdown) and “C” (second touchdown) samples, and several carbonaceous chondrites to evaluate potential genetic relationships between Ryugu and known chondrite groups and track the cosmic ray exposure history of Ryugu. We resolved Nd and Sm isotopic anomalies in small (<20 ng Nd and Sm) sample sizes via thermal ionization mass spectrometer using 1013 Ω amplifiers. Ryugu samples exhibit resolvable negative μ142Nd values consistent with carbonaceous chondrite values, suggesting that Ryugu is related to the parent bodies of carbonaceous chondrites. Ryugu's negative μ149Sm values are the result of exposure to galactic cosmic rays, as demonstrated by the correlation between 150Sm/152Sm and 149Sm/152Sm ratios that fall along the expected neutron capture correlation line. The neutron fluence calculated in the “A” samples (2.75 ± 1.94 × 1015 n cm−2) is slightly higher compared to the “C” samples (0.95 ± 2.04 × 1015 n cm−2), though overlapping within measurement uncertainty. The Sm results for Ryugu, at this level of precision, thus are consistent with a well-mixed surface layer at least to the depths from which the “A” and “C” samples derive.

Original languageEnglish
JournalMeteoritics and Planetary Science
Number of pages17
ISSN1086-9379
DOIs
Publication statusE-pub ahead of print - 2024

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© 2023 The Meteoritical Society.

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