隕石の129Cmと247Cmは,太陽のrプロセスの元素の最後の天体物理的源を制限しています
Benoit Côté1,2,3, Marius Eichler4, Andrés Yagüe López5
1Research Centre for Astronomy and Earth Sciences, Eötvös Loránd Research Network, Konkoly Observatory, 1121 Budapest, Hungary. benoit.cote@csfk.org.
まとめ
隕石は太陽系の初期構成を明らかにした 隕石におけるヨウ素-129とキュリウム-247の比率は,中性子星の融合が急速な中性子捕獲プロセス (rプロセス) を通して重元素を生成することを示唆している.
科学分野:
- 宇宙化学と核天体物理学
- 太陽系の重元素の起源を調査する
背景:
- 隕石は初期の太陽系の化学組成について 重要な洞察力を与えてくれます
- 急速な中性子捕獲プロセス (r-プロセス) は,鉄よりも重い元素を合成する責任がありますが,その天体物理的な場所は不明です.
研究 の 目的:
- 太陽系形成前の最後の r-プロセスイベントの天体物理的な場所を制限します.
- 隕石の保存されたヨウ素-129 (129I) とキュリウム-247 (247Cm) をトレーサーとして利用する.
主な方法:
- 隕石で129I/247Cmの比率を測定した
- ニュートロン星合併と磁気回転超新星シミュレーションによる核合成の計算と比較した.
- 129Iと247Cmのほぼ同一の半減期を利用して,その生産比を維持した.
主要な成果:
- 測定された129I/247Cmの隕石比は438±184と決定された.
- 核合成の計算では,中等に中性子豊富な条件が,この観測比率と最も一致していることが示されています.
- これらの条件は,中性子星の融合ディスクの放出物で頻繁にシミュレートされます.
結論:
- 中性子星の融合は,初期の太陽系に組み込まれた r-プロセス元素の源である可能性が高い.
- この研究は,核合成を理解するために隕石における同位体比の重要性を強調している.
- 核物理学のデータの不確実性は,現在これらの結論への信頼を制限しています.
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