ヨーロッパの磁気署名: 1996年12月19日のガリレオのパスからの報告
M G Kivelson1, K K Khurana, S Joy
1Institute of Geophysics and Planetary Physics and Department of Earth and Space Sciences, University of California, Los Angeles, Los Angeles, CA 90095-1567, USA.
Science (New York, N.Y.)
|May 23, 1997
まとめ
ガリレオ宇宙船のデータは,木星の衛星であるヨーロッパには,磁場乱れによって証明される内部磁場がある可能性があることを示唆しています. しかし,この内部フィールドは確認されず,その方向性は異常です.
科学分野:
- 惑星科学は惑星科学である.
- マグネトヒドロダイナミクス
- 地質物理学 地質物理学とは地質物理学です.
背景:
- 木星の衛星ユーロパは薄い大気を持ち,木星の強力な磁気圏と相互作用しています.
- 以前のミッションは,ユーロパの固有の磁気特性に関する限られたデータを提供した.
研究 の 目的:
- ヨーロッパの近くでガリレオ宇宙船によって観測された磁場乱射の源を調査する.
- ユーロパに固有の磁場があるかどうかを判断し,その性質を特徴づける.
主な方法:
- 1996年12月19日,ガリレオ宇宙船が欧州の近くを通過した際の磁気計データ解析.
- 内部ヨーロッパ二極場と外部プラズマ電流の仮説をテストするために磁場乱射のモデリング.
主要な成果:
- 観測された磁場乱れは,木星の背景磁場から著しく逸脱する.
- データは,約240ナノテスラまでのヨーロッパを中心とした二極モメントと一致しており,潜在的な内部フィールドを示唆しています.
- 二極の向きは,ユーロパのスピン軸と木星の強制されたフィールドに傾いているが,これはダイナモで生成されたフィールドでは珍しい.
- ヨーロッパの近くの小規模な波動は,局所的なプラズマ電流の影響を示唆しています.
結論:
- データは内部ユーロパ・ディポール・フィールドでモデル化できるが,その存在は確認されていない.
- 潜在的な二極の斜方向は,コアダイナモメカニズムによって簡単に説明できません.
- プラズマ電流は,ヨーロッパ近くの小さな磁場変動に寄与している可能性が高い.
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