土星の無線時計を太陽風の速度によって調節する

Philippe Zarka¹, Laurent Lamy, Baptiste Cecconi

¹Laboratoire d'Etudes Spatiales et d'Instrumentation en Astrophysique, Observatoire de Paris, Centre National de la Recherche Scientifique, Université Pierre et Marie Curie, Université Paris Diderot, 92190 Meudon, France. philippe.zarka@obspm.fr

Nature

|November 13, 2007

まとめ

土星の無線回転周期は恒定ではない. 変動は太陽風の速度と関連しており,惑星の磁気圏とラジオ時計に対する外部の制御を示唆しています. これは,惑星の自転に関する我々の理解に影響を与える.

科学分野:

惑星科学惑星科学
宇宙物理学宇宙物理学
ラジオ天文学ラジオ天文学

背景:

巨大惑星の内部回転速度を正確に測定するのは難しい.
惑星の磁場に関連したラジオ放射は,回転のプロキシとして使用されます.
当初恒定と考えられていた土星のキロメートル放射線 (SKR) 周期は,長期的な変動を示している.

研究の目的:

土星のSKR期間の短期的な変動を調査するために.
これらの観測された周期変動に影響を与える要因を決定する.
土星の回転プロキシと太陽風の条件の関係を理解するために.

主な方法:

土星のキロメートル放射線 (SKR) データの分析.
SKR周期変動と太陽風のパラメータ (速度,密度,圧力,磁場) の相関分析.
SKR期間の短期と長期の変動の比較.

主要な成果:

土星のSKR周期は,20〜30日のスケールで+/-1%の系統的な変動を示しています.
これらの短期的な変動は,土星の太陽風の速度と強く相関しています.
太陽風の密度,動的圧力,磁場強度との相関は見つかりませんでした.

結論:

土星の無線時計は,外部の条件,特に太陽風の速度によって大きく影響を受けます.
惑星の磁気圏と関連する放射能は,太陽風によって調節されます.
土星の自転周期の長期的変動は,太陽風によって引き起こされるこれらの短期的な変動の平均値である可能性が高い.

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