まとめ
アルミニウム-26は,南太平洋の堆積物で高いレベルで見つかりました. これは,太陽フレアによって活性化される惑星間塵が,宇宙線のスパラーションではなく,重要な源であることを示しています.
科学分野:
- 宇宙化学 (コスモケミストリー)
- 核天体物理学 核天体物理学とは
- 地質化学 地質化学
背景:
- アルミニウム-26 (26Al) は,コスモゲン系放射性核酸である.
- 地球上のサンプルの存在は,宇宙線相互作用または地球外の源から生じる可能性があります.
- 以前のモデルでは,宇宙線のスパラーションと惑星間塵の蓄積による寄与を推定していた.
研究 の 目的:
- 南太平洋の沈殿物サンプルで検出されたアルミニウム-26の源を調査するために.
- 測定された26Alレベルと,異なる生産経路からの予測を比較するために.
- 太陽粒子流と惑星間塵の蓄積のモデルを検証する.
主な方法:
- 南太平洋の沈殿物サンプルからアルミニウム26含有量の分析.
- 乾燥堆積物の1kgあたり26Alの分解速度を測定する.
- 測定値と理論的な推定値の比較で,惑星間塵における宇宙線散離と太陽フレアによる活動について調べました.
主要な成果:
- 乾燥した沈殿物の1キログラムあたり1分間に0.8回の分解率を測定した.
- この割合は,大気中のアルゴンの宇宙線スペラレーションから予想されるよりも大幅に高い.
- 観測された26Al濃度は,主に太陽フレア粒子によって活性化された惑星間塵の蓄積に起因する.
結論:
- 堆積物サンプルにおけるアルミニウム26の高いレベルは,太陽フレアで活性化された惑星間塵が,地上の増殖に大きく貢献していることを確認しています.
- この発見は,太陽粒子フックスと惑星間塵の地上増殖速度に関する以前の推定値の大きさの正確さを検証するものである.
- この研究は,地球上の宇宙的放射性核酸堆積の提案されたメカニズムを支持する経験的証拠を提供します.
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