木星の上層大気圏における超音速乱流の証拠
C Emerich1, L B Jaffel, J T Clarke
1Institut d'Astrophysique Spatiale, CNRS, F-91405 Orsay, France.
まとめ
木星の上層大気は驚くほど乱れていて,その日光の中で超音速の速度を示しています. ハッブル宇宙望遠鏡の観測により,複雑な水素ライマンアルファ (Ly-alpha) 放射プロファイルが明らかになり,ダイナミックな木星の環境を示しています.
科学分野:
- 惑星科学 惑星科学
- 大気物理学 大気物理学
- 宇宙物理学 宇宙物理学
背景:
- 水素ライマン・アルファ (Ly-alpha) 放射は,ガス巨人の大気条件の重要な指標である.
- 以前の観測は,木星の上層大気が比較的安定していることを示唆していた.
研究 の 目的:
- 木星のLy-alpha昼光放射の詳細な構造と変動性を分析するために.
- 木星の上層大気圏で発生するダイナミックなプロセスを調査するために.
主な方法:
- ハッブル宇宙望遠鏡 (HST) のゴダード高解像度スペクトログラフ (GHRS) を利用しました.
- 木星のLy-alpha放射線プロファイルの高解像度スペクトルを取得しました.
- 時間の変動を分単位で分析した.
主要な成果:
- 観察された複雑で高度に変動するLy-alpha排出ラインプロファイル.
- 低緯度のLy-alpha膨らみ領域で有意な構造物が検出されました.
- これらの構造は超音速 (数から数十km/s) に対応する.
結論:
- 木星の上層大気は,予想外にも動的で嵐のようなものです.
- 観測された超音速は,惑星の大気に関する以前の仮定に異議を唱える.
- 木星の上層大気には,恒星のような大気現象が表れています.
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