2023 Fiscal Year Final Research Report
Study of Martian core structure based on density and sound velocity measurements
| Project/Area Number |
20H02008
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Review Section |
Basic Section 17040:Solid earth sciences-related
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| Research Institution | Okayama University |
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Principal Investigator |
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| Co-Investigator(Kenkyū-buntansha) |
米田 明 大阪大学, 大学院理学研究科, 招へい研究員 (10262841)
鎌田 誠司 東北大学, 理学(系)研究科(研究院), その他 (30611793)
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| Project Period (FY) |
2020-04-01 – 2024-03-31
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| Keywords | コア / 密度 / 弾性波速度 / 鉄合金 / 液体 / 火星 / 高温高圧 |
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| Outline of Final Research Achievements |
To determine the density and equation of state of Fe-Ni alloy solids and liquids under Martian core condition and to constrain the size and composition of the Martian core, we developed density measurement using the X-ray absorption method combined with a laser-heated diamond anvil cell (DAC). Determination of elastic wave velocities under Martian core pressures using the GHz ultrasonic method is another target of this project. Densities of Fe, Ni and FeS solid and liquid samples were successfully determined accurately up to 26 GPa and 3000 K as a result by using newly developed density measurement setup. The P-wave velocities of Fe solid was successfully determined up to 34 GPa which corresponds to the Martian core pressure.
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| Free Research Field |
高圧地球惑星科学
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| Academic Significance and Societal Importance of the Research Achievements |
本研究のレーザー加熱式DACを用いたX線吸収法による密度測定の開発により、26 GPa, 3000 Kまでの圧力・温度条件での高精度の密度測定が可能となった。特にX線吸収法の測定温度限界を従来の720 Kから3000 Kまで大きく拡張できた。本研究により液体の密度測定を火星コア条件で実施でき、さらに液体密度を高精度で決定可能になった点で、本研究は極めて大きな意義を持つ。加えてGHz超音波法により火星コア圧力条件までP波・S波速度測定ができ、弾性を決定可能となった点でも本研究の学術的インパクトは大きい。
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