エンケラドスの羽根の緩やかな塵は,タイガーストライプの骨折における凝縮と壁衝突によるものです
Jürgen Schmidt1, Nikolai Brilliantov, Frank Spahn
1Nichtlineare Dynamik, Universität Potsdam, Am Neuen Palais 10, 14469 Potsdam, Germany. jschmidt@agnld.uni-potsdam.de
Nature
|February 8, 2008
まとめ
科学者たちはエンケラドスをモデルにしました.
科学分野:
- 惑星科学は惑星科学である.
- 天体生物学 アストロバイオロジー
- 地質物理学 地質物理学とは地質物理学です.
背景:
- カッシーニ宇宙船は,エンケラドスの南極から水蒸気と氷の粒子の羽根を発見した.
- 氷の粒子の観測された低速度は,羽根の水蒸気と比較して,科学的な課題を提示しています.
- 羽根の稀な性質は,表面下での相互作用が速度差の原因であることを示唆しています.
研究 の 目的:
- エンケラドスの羽根の氷の粒子の減速を説明するモデルを開発する.
- エンケラドスの地下運河内の粒子の形成と振る舞いを支配する物理的プロセスを調査する.
- 地下液体の水の存在に対する羽根の組成とダイナミクスの影響を評価する.
主な方法:
- 変化幅のチャネル内の穀物の凝縮と成長をシミュレートするために,計算モデルが開発されました.
- モデルには,穀物壁との衝突と,ガス流による再加速が組み込まれています.
- 粒子の速度と大きさの分布を導き出し,カッシーニのデータと比較した.
主要な成果:
- このモデルは,繰り返し発生する粒子の壁との衝突とガスの再加速が,効率的な摩擦を生み出し,粒子の速度が低いことを説明していることを示しています.
- 派生した粒子の速度と大きさの分布は,エンケラドスの塵の羽の観測および推論された性質を成功裏に複製します.
- ガス密度は,水の三重点の近くで形成されたことを示唆し,260K以下の温度では,測定された粒子フローには不十分である.
結論:
- この発見は,エンケラドスの羽根の氷の粒と水蒸気との間の観測された速度差の自然な説明を提供します.
- この結果は,エンケラドスの南極の下に地下液体水海が存在することを強く示唆しています.
- この研究は,月の観測可能な羽根の活動を形作る上で,地表の過程の重要性を強調しています.
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