2021 Fiscal Year Final Research Report
Solar wind interaction with the moon in the scale between magnetohydrodyamic and cyclotron radius scales
| Project/Area Number |
18K03727
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Review Section |
Basic Section 17010:Space and planetary sciences-related
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| Research Institution | Tohoku Institute of Technology |
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Principal Investigator |
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| Project Period (FY) |
2018-04-01 – 2022-03-31
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| Keywords | 月 / 太陽風プラズマ / 磁場変動 / かぐや衛星 / リム圧縮 / ホイスラ波 / シアーアルフベン波 / サイクロトロン |
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| Outline of Final Research Achievements |
Knowledge of solar wind interaction with the moon has been renewed by recent high time resolution observations. In addition to previously known hydrodynamic scale phenomena such as wake formation and upstream wave generation by reflected ions, we have studied magnetic field variations such as limb compression and diamagnetic cavities with magnetic enhancements with duration shorter than ion gyro period, shear Alfven waves generated at thin wake boundary, or diffuse whistler mode waves above the polar region separated from their generator ions. Their generation mechanisms were related with smallness of the magnetic anomaly, lunar radius smaller than the Larmour radius of the ions reflected by the moon, or thin boundary of the lunar wake.
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| Free Research Field |
太陽風プラズマ物理学
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| Academic Significance and Societal Importance of the Research Achievements |
近年、実利用への関心が高まっている月であるが、その電磁環境が十分に知られているとは言い難い。着陸機の軌道制御に月の磁場を利用するようなアイディアがあったとしても、太陽風との相互作用によって時に３－４倍も磁場強度が変動することを知らないと危険である。本研究は、これまで知られていた反射イオンによる昼側低周波磁場変動に加え、新たにウェイク中の低周波アルフベン波、月の極域の広帯域ホイスラ波、昼夜境界の小スケールリム圧縮について解明したものである。
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