鉛に富んだ3つの星の発見
S Van Eck1, S Goriely, A Jorissen
1Institut d'Astronomie et d'Astrophysique, Université Libre de Bruxelles, Boulevard du Triomphe, C.P. 226, B-1050 Bruxelles, Belgium. svaneck@astro.ulb.ac.be
Nature
|August 24, 2001
まとめ
研究者らは,金属が少ない3つの星で大量の鉛を発見した. この発見は,恒星がアシンプトティック・ジャイアント・ブランチ・フェーズ中にゆっくりとした中性子捕獲プロセス (sプロセス) を通して重元素を合成するという理論を支持する.
科学分野:
- 天文学 天文学
- 恒星の進化について
- 核天体物理学 核天体物理学とは
背景:
- 鉄よりも重い安定した核の半分は,質量が低いから中等な恒星 (0.8〜8太陽質量) で合成されています.
- これらの元素は,アシンプトティック・ジャイアント・ブランチ (AGB) 段階において,恒星風によって星間媒介に放出されます.
- 遅い中性子捕獲プロセス (s-プロセス) は,恒星内の鉄核からより重い元素を構築します.
研究 の 目的:
- 金属が少ない恒星における鉛やその他の重元素の豊富さを調査する.
- アシンプトティック・ジャイアント・ブランチ (AGB) の恒星における核合成のモデルをテストする.
- 恒星の内部におけるsプロセスの動作を確認するために.
主な方法:
- 金属が少ない3つの星 (HD187861,HD196944,HD224959) の元素の豊富さの分析
- 星の組成を決定するスペクトル解析.
- 観測された豊富さの比較と,恒星核合成モデルの予測.
主要な成果:
- 研究された3つの金属に乏しい星において,鉛の濃度の有意な濃度の発見.
- 観測された鉛の豊富さは,これらの恒星における他の重元素よりも高い.
- 鉛やその他の重元素の観測値と予測値との間の絶好調な一致.
結論:
- この発見は,AGB星におけるsプロセスによる重元素合成の理論を裏付けている.
- この研究は,金属度が低い恒星環境における核合成の理解を強化する.
- 観測された鉛の過剰量は,初期の銀河系AGBの星で動作するsプロセスのモデルと一致しています.
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