大気中の分子塊が AGB 星の周周回包膜を形成する
L Velilla-Prieto1, J P Fonfría2, M Agúndez3
1Department of Molecular Astrophysics, Instituto de Física Fundamental, Madrid, Spain. l.velilla@csic.es.
Nature
|May 17, 2023
まとめ
観測により,アシンプトティック・ジャイアント・ブランチ (AGB) の星の大気中の塊状の分子ガスと塵が明らかになった. これらの構造はコンベクティブ・セルとパルスによって駆動され 恒星の環状封筒を形成します
科学分野:
- 天文学と天体物理学
- 星の進化について
- 恒星周りの環境
背景:
- アシンプトティック・ジャイアント・ブランク (AGB) の星は物質を放出し 塵の覆いを形成します
- 前回の観測では 酸素に富んだ恒星の近くで 塊状の塵と 不均一な分子ガスが観測されました
- 炭素 AGB 星の塵形成領域の構造は,解像度が限られているため,まだ十分に理解されていません.
研究 の 目的:
- 炭素 AGB の星 IRC+10°216 の大気中の分子ガスと新しく形成された塵の分布を調査する.
- 炭素 AGB 星の物質の放出メカニズムを理解する
- 星半径のスケールで 構造を解明する
主な方法:
- IRC+10°216の大気の高解像度イメージング
- 分子ガス線 (HCN,SiS,SiC2) の観測
- 粉塵の形成と分布の分析
主要な成果:
- HCN,SiS,SiC2の線が異なる半径で,別々の塊の中に分かれていることが検出されました.
- 恒星光圏の大きなコンベクティブ細胞として解釈した.
- 恒星脈動でコンベクティブ細胞が合体し,アニゾトロピーを生み出します.
結論:
- 光球のコンベクティブ細胞は,パルスと潜在的な伴侶と組み合わせて,炭素 AGB 星の環状封筒を形作る重要な要因です.
- この発見は 恒星の大気と塵の形成地帯で 起こる過程について 前例のない詳細を 提供しています
- この研究は,進化した星の質量損失と封筒形成の理解を進める.
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