start-ver=1.4 cd-journal=joma no-vol=965 cd-vols= no-issue=1 article-no= start-page=52 end-page= dt-received= dt-revised= dt-accepted= dt-pub-year=2024 dt-pub=20240404 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Unraveling the Cr Isotopes of Ryugu: An Accurate Aqueous Alteration Age and the Least Thermally Processed Solar System Material en-subtitle= kn-subtitle= en-abstract= kn-abstract=The analysis of samples returned from the C-type asteroid Ryugu has drastically advanced our knowledge of the evolution of early solar system materials. However, no consensus has been obtained on the chronological data, which is important for understanding the evolution of the asteroid Ryugu. Here, the aqueous alteration age of Ryugu particles was determined by the Mn–Cr method using bulk samples, yielding an age of 4.13 + 0.62/−0.55 Myr after the formation of Ca–Al-rich inclusions (CAI). The age corresponds to 4563.17 + 0.60/−0.67 Myr ago. The higher 55Mn/52Cr, ε54Cr, and initial ε53Cr values of the Ryugu samples relative to any carbonaceous chondrite samples implies that its progenitor body formed from the least thermally processed precursors in the outermost region of the protoplanetary disk. Despite accreting at different distances from the Sun, the hydrous asteroids (Ryugu and the parent bodies of CI, CM, CR, and ungrouped C2 meteorites) underwent aqueous alteration during a period of limited duration (3.8 ± 1.8 Myr after CAI). These ages are identical to the crystallization age of the carbonaceous achondirtes NWA 6704/6693 within the error. The ε54Cr and initial ε53Cr values of Ryugu and NWA 6704/6693 are also identical, while they show distinct Δ'17O values. This suggests that the precursors that formed the progenitor bodies of Ryugu and NWA 6703/6693 were formed in close proximity and experienced a similar degree of thermal processing in the protosolar nebula. However, the progenitor body of Ryugu was formed by a higher ice/dust ratio, than NWA6703/6693, in the outer region of the protoplanetary disk. en-copyright= kn-copyright= en-aut-name=TanakaRyoji en-aut-sei=Tanaka en-aut-mei=Ryoji kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=RatnayakeDilan M. en-aut-sei=Ratnayake en-aut-mei=Dilan M. kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=OtaTsutomu en-aut-sei=Ota en-aut-mei=Tsutomu kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=MiklusicakNoah en-aut-sei=Miklusicak en-aut-mei=Noah kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=KunihiroTak en-aut-sei=Kunihiro en-aut-mei=Tak kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=5 ORCID= en-aut-name=PotiszilChristian en-aut-sei=Potiszil en-aut-mei=Christian kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=6 ORCID= en-aut-name=SakaguchiChie en-aut-sei=Sakaguchi en-aut-mei=Chie kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=7 ORCID= en-aut-name=KobayashiKatsura en-aut-sei=Kobayashi en-aut-mei=Katsura kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=8 ORCID= en-aut-name=KitagawaHiroshi en-aut-sei=Kitagawa en-aut-mei=Hiroshi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=9 ORCID= en-aut-name=YamanakaMasahiro en-aut-sei=Yamanaka en-aut-mei=Masahiro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=10 ORCID= en-aut-name=AbeMasanao en-aut-sei=Abe en-aut-mei=Masanao kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=11 ORCID= en-aut-name=MiyazakiAkiko en-aut-sei=Miyazaki en-aut-mei=Akiko kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=12 ORCID= en-aut-name=NakatoAiko en-aut-sei=Nakato en-aut-mei=Aiko kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=13 ORCID= en-aut-name=NakazawaSatoru en-aut-sei=Nakazawa en-aut-mei=Satoru kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=14 ORCID= en-aut-name=NishimuraMasahiro en-aut-sei=Nishimura en-aut-mei=Masahiro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=15 ORCID= en-aut-name=OkadaTatsuaki en-aut-sei=Okada en-aut-mei=Tatsuaki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=16 ORCID= en-aut-name=SaikiTakanao en-aut-sei=Saiki en-aut-mei=Takanao kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=17 ORCID= en-aut-name=TanakaSatoshi en-aut-sei=Tanaka en-aut-mei=Satoshi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=18 ORCID= en-aut-name=TeruiFuyuto en-aut-sei=Terui en-aut-mei=Fuyuto kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=19 ORCID= en-aut-name=TsudaYuichi en-aut-sei=Tsuda en-aut-mei=Yuichi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=20 ORCID= en-aut-name=UsuiTomohiro en-aut-sei=Usui en-aut-mei=Tomohiro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=21 ORCID= en-aut-name=WatanabeSei-ichiro en-aut-sei=Watanabe en-aut-mei=Sei-ichiro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=22 ORCID= en-aut-name=YadaToru en-aut-sei=Yada en-aut-mei=Toru kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=23 ORCID= en-aut-name=YogataKasumi en-aut-sei=Yogata en-aut-mei=Kasumi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=24 ORCID= en-aut-name=YoshikawaMakoto en-aut-sei=Yoshikawa en-aut-mei=Makoto kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=25 ORCID= en-aut-name=NakamuraEizo en-aut-sei=Nakamura en-aut-mei=Eizo kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=26 ORCID= affil-num=1 en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University kn-affil= affil-num=2 en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University kn-affil= affil-num=3 en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University kn-affil= affil-num=4 en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University kn-affil= affil-num=5 en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University kn-affil= affil-num=6 en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University kn-affil= affil-num=7 en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University kn-affil= affil-num=8 en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University kn-affil= affil-num=9 en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University kn-affil= affil-num=10 en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University kn-affil= affil-num=11 en-affil=Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency kn-affil= affil-num=12 en-affil=Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency kn-affil= affil-num=13 en-affil=Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency kn-affil= affil-num=14 en-affil=Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency kn-affil= affil-num=15 en-affil=Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency kn-affil= affil-num=16 en-affil=Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency kn-affil= affil-num=17 en-affil=Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency kn-affil= affil-num=18 en-affil=Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency kn-affil= affil-num=19 en-affil=Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency kn-affil= affil-num=20 en-affil=Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency kn-affil= affil-num=21 en-affil=Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency kn-affil= affil-num=22 en-affil=Department of Earth and Planetary Sciences, Nagoya University kn-affil= affil-num=23 en-affil=Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency kn-affil= affil-num=24 en-affil=Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency kn-affil= affil-num=25 en-affil=Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency kn-affil= affil-num=26 en-affil=The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University kn-affil= END start-ver=1.4 cd-journal=joma no-vol=936 cd-vols= no-issue=2 article-no= start-page= end-page= dt-received= dt-revised= dt-accepted= dt-pub-year=2022 dt-pub=202291 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Low-J Transitions in A˜2Π(0,0,0)−X˜2Σ+(0,0,0) Band of Buffer-gas-cooled CaOH en-subtitle= kn-subtitle= en-abstract= kn-abstract=Calcium monohydroxide radical (CaOH) is receiving an increasing amount of attention from the astrophysics community as it is expected to be present in the atmospheres of hot rocky super-Earth exoplanets as well as interstellar and circumstellar environments. Here, we report the high-resolution laboratory absorption spectroscopy on low-J transitions in A ˜ 2 Π ( 0 , 0 , 0 ) − X ˜ 2 Σ + ( 0 , 0 , 0 ) band of buffer-gas-cooled CaOH. In total, 40 transitions out of the low-J states were assigned, including 27 transitions that have not been reported in previous literature. The determined rotational constants for both ground and excited states are in excellent agreement with previous literature, and the measurement uncertainty for the absolute transition frequencies was improved by more than a factor of 3. This will aid future interstellar, circumstellar, and atmospheric identifications of CaOH. The buffer-gas-cooling method employed here is a particularly powerful method to probe low-J transitions and is easily applicable to other astrophysical molecules. en-copyright= kn-copyright= en-aut-name=TakahashiYuiki en-aut-sei=Takahashi en-aut-mei=Yuiki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=BabaMasaaki en-aut-sei=Baba en-aut-mei=Masaaki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=EnomotoKatsunari en-aut-sei=Enomoto en-aut-mei=Katsunari kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=HiramotoAyami en-aut-sei=Hiramoto en-aut-mei=Ayami kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=IwakuniKana en-aut-sei=Iwakuni en-aut-mei=Kana kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=5 ORCID= en-aut-name=KumaSusumu en-aut-sei=Kuma en-aut-mei=Susumu kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=6 ORCID= en-aut-name=TobaruReo en-aut-sei=Tobaru en-aut-mei=Reo kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=7 ORCID= en-aut-name=MiyamotoYuki en-aut-sei=Miyamoto en-aut-mei=Yuki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=8 ORCID= affil-num=1 en-affil=Division of Physics, Mathematics, and Astronomy, California Institute of Technology kn-affil= affil-num=2 en-affil=Department of Chemistry, Graduate School of Science, Kyoto University kn-affil= affil-num=3 en-affil=Department of Physics, University of Toyama kn-affil= affil-num=4 en-affil=Research Institute for Interdisciplinary Science, Okayama University kn-affil= affil-num=5 en-affil=Institute for Laser Science, University of Electro-Communications kn-affil= affil-num=6 en-affil=Atomic, Molecular and Optical Physics Laboratory, RIKEN kn-affil= affil-num=7 en-affil=Research Institute for Interdisciplinary Science, Okayama University kn-affil= affil-num=8 en-affil=Research Institute for Interdisciplinary Science, Okayama University kn-affil= END