Physicochemical conditions of the protosolar disk yielding oxygen isotopic evolution of primitive solar system solid materials

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K13986
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 17010:Space and planetary sciences-related
• Research Institution: Kyushu University (2022-2023); Japan Aerospace EXploration Agency (2021)
• Principal Investigator: Yamamoto Daiki 九州大学, 理学研究院, 助教 (00846868)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 酸素同位体進化 / 始原的太陽系物質 / 原始太陽系円盤 / 一酸化炭素 / 非晶質ケイ酸塩 / 難揮発性包有物 (CAI)

Outline of Final Research Achievements

A series of experiments between amorphous silicates/calcium-, aluminum-rich inclusions (CAI) melt and low pressure CO gas was performed in order to investigate the physicochemical conditions of the protosolar disk. We found that amorphous silicate dust would play an important role in catalyzing the isotopic equilibrium in silicate-CO-H2O system, and most of primitive silicate dust would have been thermally processed at temperatures above ~600-700 K in the dynamically accreting protosolar disk. We also found that the overall isotope exchange rate between CAI melt and disk gas would be determined by CAI melt-H2O reaction and igneous CAI would be heated at ~1400°C and the total pressure higher than ~100 Pa for ~2-3 days.

Free Research Field

惑星化学、実験宇宙化学

Academic Significance and Societal Importance of the Research Achievements

これまで定性的にか議論されてこなかった地球外物質の酸素同位体組成に関して、室内実験による反応速度データを用いて解釈をおこなうことにより、惑星材料物質 (隕石構成物質) が経験した原始太陽系円盤の物理化学的条件を分析データから定量的に引き出すことが可能となった。これにより物質化学的証拠に基づいた信頼性のある原始太陽系円盤モデルの構築が可能となることが考えられ、他の原始惑星系円盤に対しての太陽系の特異性・普遍性の解釈につながる可能性がある。