Origin of multi-polar magnetic fields at Uranus and Neptune investigated from ionic conductivity of ammonia under high pressure and high temperature

2021 Fiscal Year Final Research Report

• Project/Area Number: 20K22366
• Research Category: Grant-in-Aid for Research Activity Start-up
• Allocation Type: Multi-year Fund
• Review Section: 0204:Astronomy, earth and planetary science, and related fields
• Research Institution: Gifu University
• Principal Investigator: Kimura Tomoaki 岐阜大学, 工学部, 助教 (50624540)
• Project Period (FY): 2020-09-11 – 2022-03-31
• Keywords: 超イオン伝導体 / アンモニア / 天王星 / 高温高圧実験

Outline of Final Research Achievements

High-pressure and high-temperature generation technique has been introduced for producing the superionic phases of water-ice and ammonia which might be the origin of the multipolar magnetic field observed at Uranus and Neptune. We synthesized the powder of the pressure marker of SrB4O7: Sm2+ allowing us to determine the pressure even at the high pressure. We successfully observed the melting of　water-ice at 7 GPa and 600 K by using the developed resistive heated diamond anvil cell. Raman scattering measurement system has also been introduced, which is useful to determine material phase at high pressure and high temperature. The ionic property of the superionic phase will be revealed by using the newly developed experimental technique, which is important to elucidate the generation mechanism of the planetary magnetic fields.

Free Research Field

地球惑星科学

Academic Significance and Societal Importance of the Research Achievements

本研究で開発した高温高圧発生技術を通して、天王星や海王星の主要物質である氷やアンモニアに惑星内部環境を提供することができる。今後、これらの物質相を同定した上で、イオン伝導特性を実験的に決定することで、マントル内部構造が明らかとなり、同時に天王星と海王星で観測されている多重極磁場の成因の解明につながる成果を得られることが期待できる。