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巨大な恒星の表面での1ヶ月間のコンベクション時間スケール
Wouter Vlemmings1, Theo Khouri2, Behzad Bojnordi Arbab2
1Department of Space, Earth and Environment, Chalmers University of Technology, Gothenburg, Sweden. wouter.vlemmings@chalmers.se.
Nature
|September 11, 2024
まとめ
R Doradusのような進化した恒星のコンベクションは 表面の特徴をはっきりと示しています これらの発見は,低質量と高質量星の間で潜在的に異なるコンベクション特性を明らかにします.
科学分野:
- 天文学と天体物理学
- スター進化
- コンベクティブ・プロセス
背景:
- 恒星の進化において,特に太陽のような恒星と巨大進化した恒星において,コンベクションによるエネルギー輸送は不可欠である.
- 流動の特徴は巨大な赤い超巨大星に観察されているが,質量が低い進化した星ではその性質はよくわかっていない.
- 流動運動は,核合成産物を星間媒質に戻す恒星風を生成するために不可欠である.
研究 の 目的:
- 進化した巨大な星 R Doradus のコンベクティブ表面の特徴とダイナミクスを調査し,特徴づけること.
- 低質量進化した恒星におけるコンベクティブ時間スケールと大きさの観測上の制約を提供する.
- 低質量の恒星と高質量の恒星を比較する.
主な方法:
- R Doradusの恒星表面のインターフェロメトリック画像の再構築.
- 構造と運動を決定する恒星円盤の特徴の分析.
- 表面速度を測定してコンベクト時間尺度を推定する.
主要な成果:
- R Doradusの恒星の円盤に顕著な小規模な特徴を明らかにし,コンベクションを示しています.
- これらのコンベクティブな特徴の支配的な構造の大きさは 0.72 ± 0.05 天文単位であると決定しました.
- 測定された表面運動速度は -18から+20 km/sで,コンベクトの時間スケールは約1ヶ月です.
結論:
- 観測された特徴と動態は,R Doradusの表面上のコンベクションの直接的な証拠を提供します.
- 推定されたコンベクティブタイムスケールは,低質量と高質量進化した星の間のコンベクション特性の潜在的な違いを示唆している.
- これらの発見は,進化した星における恒星風と物質の帰還をよりよく理解するのに寄与しています.
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