恒星間中性水素の流れがヘリオスフィアのインターフェースを横断する歪み
R Lallement1, E Quémerais, J L Bertaux
1Service d'Aéronomie du Centre National de la Recherche Scientifique, Institut Pierre Simon Laplace, Boite Postale 3, 91371 Verrières-le-Buisson, France. rosine.lallement@aerov.jussieu.fr
まとめ
恒星間水素流は,ヘリオスフィアに流入するヘリウム流に比べて約4度傾斜しています. この傾きは,恒星間磁場が磁気圏を歪め,磁気コンパスとして作用することを示唆しています.
科学分野:
- *ヘリオフィジックスと星間媒体の相互作用.
- * プラズマ物理学と磁気水力学.
背景:
- *ヘリオスフィアの星間介質 (ISM) との相互作用を理解することは,宇宙気象と惑星科学にとって極めて重要です.
- *以前のモデルでは,中性ガス流れに磁場の影響が大きくなく,より単純な相互作用が示唆されていた.
研究 の 目的:
- *ヘリオスフィアに流入する中性水素の流れの正確な方向を測定する.
- * ニュートラルガスの流れで観測された傾斜の原因を調査する.
- * 水素とヘリウムの流れベクトルを利用して,星間磁場方向を制約する.
主な方法:
- *星間水素共鳴光におけるドップラーシフトの吸収セル測定.
- * 内ヘリオスフィア内の中性水素とヘリウムの流れベクトルの分析.
主要な成果:
- * 中性水素流はヘリウム流に比べて約4度傾斜しています.
- *観測された傾きは,磁場効果がないモデルと矛盾しています.
- *水素とヘリウムの流れベクトルは,恒星間磁場に方向的な制約を与える.
結論:
- * 周りの恒星間磁場は,ヘリオスフィアを大きく歪める.
- * 中性水素流の傾きは,ヘリオスフィアの歪みの指標として機能する.
- *水素とヘリウムの流動ベクトルの組み合わせは,効果的な恒星間磁気コンパスとして機能します.
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