アルフヴェン波の証拠は太陽のX線ジェットにある
J W Cirtain1, L Golub, L Lundquist
1Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA. Jonathan.W.Cirtain@nasa.gov
まとめ
新しい観測により,極の冠状孔から発生する多数の高速X線ジェットが明らかになった. これらのダイナミックなイベントは,頻繁に発生し,高速太陽風に大きく寄与する可能性があります.
科学分野:
- ソーラー物理学 ソーラー物理学
- プラズマ天体物理学とは
- 宇宙 天気 スペース天気
背景:
- 冠状磁場は非常にダイナミックで,磁気再接続のようなプロセスを経てます.
- 磁気再接続は,かなりのエネルギーを放出し,太陽フレア,冠状質量噴射,小規模なX線ジェットなどの現象を引き起こします.
- 以前のX線ジェットの観測では,イベントの発生率と速度が低いことが記録されていた.
研究 の 目的:
- 極の冠状孔におけるX線ジェットの特性と周波数を調査する.
- 観測されたこれらのX線ジェットの速度と寸法を決定するために.
- 太陽風に対するX線ジェットの潜在的貢献を評価する.
主な方法:
- 北極の冠状孔のヒノード観測を利用した.
- X線ジェットイベントを検出し,分析しました.
- 測定されたジェット速度,寸法,および持続時間.
主要な成果:
- アルフヴェン速度の近く (~800 km/s) と音速の近く (200 km/s) の2つの異なる速度集団を持つX線ジェットを発見した.
- 以前の報告と比較して,事件の頻度が平均10件/時間,著しく高かった.
- 特徴的なジェットは,2 x 10^3 から 2 x 10^4 km の幅,1 x 10^5 km の長さ,および 100-2500 秒間の長さである.
結論:
- 高い数とX線ジェットの速度は,X線ジェットが一般的でエネルギッシュな現象であることを示唆しています.
- これらの発見は,X線ジェットが高速な太陽風の加速と形成に重要な役割を果たしていることを示しています.
- これらのジェットが太陽風の動力学と宇宙天候に及ぼす影響を完全に理解するために,さらなる研究が必要です.
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