Determination of the initial abundance of presently extinct nuclide Cs-135 in the early solar system and its chronometrical applications
| Project/Area Number |
16K13915
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| Research Category |
Grant-in-Aid for Challenging Exploratory Research
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| Allocation Type | Multi-year Fund |
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| Research Field |
Geochemistry/Cosmochemistry
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| Research Institution | Nagoya University |
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Principal Investigator |
Hidaka Hiroshi 名古屋大学, 環境学研究科, 教授 (10208770)
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| Project Period (FY) |
2016-04-01 – 2019-03-31
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| Project Status |
Completed (Fiscal Year 2018)
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| Budget Amount *help |
¥3,510,000 (Direct Cost: ¥2,700,000、Indirect Cost: ¥810,000)
Fiscal Year 2018: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
Fiscal Year 2017: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
Fiscal Year 2016: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
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| Keywords | 隕石 / バリウム / セシウム / 同位体 / 水質変成 / 原始太陽系 / 原子核合成 / 135-セシウム / 消滅核種 / 太陽系始原物質 / 同位体年代学 |
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| Outline of Final Research Achievements |
The aqueous alteration is one of the primitive activities on the early solar planetary bodies. In this study, precise determination of Ba isotopic compositions for the chemical separates with stepwise acid leaching technique were performed on five carbonaceous chondrites. As the isotopic results, it is concluded that several kinds of nucleosynthetic components out of the solar system were added heterogeneously in the meteorite parent bodies, and that these additional nucleosynthetic components interfere the existence of radiogenic Ba-135 decayed from Cs-135. Additionally, in-situ Ba isotopic analyses by using an ion micro probe were performed on individual minerals of one of five samples, the Tagish Lake meteorite. No isotopic evidence for the radiogenic Ba-135 was found in the individual minerals.
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| Academic Significance and Societal Importance of the Research Achievements |
太陽系の進化については、天文学、宇宙物理学における観測や数値シミュレーションによるアプローチから構築されるモデルと、太陽系の始原惑星物質であるコンドライトの鉱物学的観察や化学組成・同位体組成などの物質科学的な分析データに基づく進化モデルとの融合は必須である。本研究で太陽系の始原惑星物質に含まれるバリウムの同位体不均一性を見出せたことは、原始太陽系の物理化学的環境を考察するうえで宇宙科学的意義がある。本研究で用いた炭素質コンドライトは、現在進行中である、2020年に帰還予定のハヤブサ2のリターンサンプル計画と今後、密接に関係してくることから社会的関心は高く、意義がある。
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Report
(4 results)
Research Products
(51 results)
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[Presentation] H. Hidaka2018
Author(s)
Systematic REE isotopic analyses for cosmochemistry
Organizer
The 9th Symposium on Polar Science
Related Report
Int'l Joint Research / Invited
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