2022 Fiscal Year Final Research Report
Physicochemical conditions of the protosolar disk constrained by the survivability of presolar grains in the early solar system
| Project/Area Number |
19K23474
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| Research Category |
Grant-in-Aid for Research Activity Start-up
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| Allocation Type | Multi-year Fund |
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| Review Section |
0204:Astronomy, earth and planetary science, and related fields
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| Research Institution | Kyushu University (2022)
Japan Aerospace EXploration Agency (2019-2021) |
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Principal Investigator |
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| Project Period (FY) |
2019-08-30 – 2023-03-31
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| Keywords | プレソーラー粒子 / 炭化ケイ素 / アルミナ / 原始太陽系円盤 / 蒸発 / 酸素同位体交換 / 残存可能性 |
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| Outline of Final Research Achievements |
Evaporation experiments of SiC under low-pressure H2-H2O gas mixture revealed that the evaporation rates of SiC depend on heating temperature, duration, and gas composition. The presence of thin SiO2 layer on the surface of the experimental charges was confirmed by TEM. The evaporation flux depends only weakly on temperatures higher than 1350-1400°C, while larger temperature dependence of the evaporation flux was observed at temperatures < 1300°C. The present experimental results reveal the survivability of presolar SiC in the disk as a function of temperature and PH2O.
Experimental results of alumina dust indicated that oxygen isotope exchange of amorphous alumina dust precedes its crystallization at low temperatures, suggesting that oxygen isotopic compositions of presolar amorphous alumina dust incorporated in the protosolar disk would be readily erased by oxygen isotope exchange with the solar disk gas in the earliest solar system.
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| Free Research Field |
宇宙惑星化学
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| Academic Significance and Societal Importance of the Research Achievements |
プレソーラーSiC粒子、アルミナ粒子の残存可能性が明らかになったことにより、始原的隕石中の物質が経験した原始太陽系円盤の物理化学条件の制約が可能となる。また先行研究のプレソーラー珪酸塩粒子の残存可能性条件の結果をあわせることで、始原的隕石の観察結果から与えられている種々のプレソーラー粒子の存在量比との詳細な比較から原始太陽系円盤の物理化学条件の詳細な決定や、原始太陽系円盤に持ち込ま得れたプレソーラー粒子の状態 (熱力学的安定相か不安定相であるか) の推定につながると考えられる。具体的には、隕石中のプレソーラー酸化物・珪酸塩の存在量比の変化と実験的に決定したプレソーラーアルミナ・ケイ酸塩粒子
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