メインベルトの小惑星の崩壊によるミオセンの終わりの塵のシャワー
Kenneth A Farley1, David Vokrouhlický, William F Bottke
1Division of Geological and Planetary Sciences, California Institute of Technology, MS 170-25, Pasadena, California 91125, USA. farley@gps.caltech.edu
Nature
|January 20, 2006
まとめ
8300万年前の大きな小惑星の衝突により,地球に到達する惑星間塵粒子が著しく増加しました. 海底ヘリウム-3 (3He) の記録は,この出来事を明らかにし,ベリタス族の断片からのIDP流の4倍の増加を示しています.
科学分野:
- 惑星科学は惑星科学である.
- 地質化学 地質化学
- 宇宙塵の研究 宇宙塵の研究
背景:
- 地球は,惑星間塵粒子 (IDP),小惑星や彗星からの断片で絶えず爆撃されています.
- IDPの流れは一般的に安定しており,新しい粒子が様々なプロセスで失われた粒子を置き換えます.
- IDPにはヘリウム-3 (3He) が含まれており,海底沈殿物の3He濃度が過去のIDP流動のプロキシーとなる.
研究 の 目的:
- 地質学的時間における惑星間塵粒子の (IDP) 流動と源体を影響する主要な出来事を調査する.
- 小惑星の衝突が地上のIDP増殖速度に与える影響を分析する.
- 海底の3He記録を特定の天文学的出来事と相関させるため.
主な方法:
- IDP流動のプロキシとして海底沈殿物の3He濃度の分析.
- ヴェリタスの小惑星ファミリーの破壊イベントの日付.
- IDP流量データと小惑星の軌道データ,その他の地質学的記録の比較.
主要な成果:
- およそ830万年前,ベリタス小惑星ファミリーの衝突による破壊は,IDP流の一時的な増加を引き起こしました.
- IDPの流れは,事件前の約4倍のレベルでピークに達し,約150万年間続いた.
- ヴェリタス族の断片は,ミオセンの後半の陸上のIDP増殖率を支配していた.
結論:
- 小惑星の衝突は,地球に到達する惑星間塵粒子の流れを大きく,一時的に変化させることができます.
- 海底3Heの記録は,過去のIDP流動変動を再構築し,太陽系の大規模なイベントを特定するための貴重なツールを提供します.
- 3500万年前の3He記録にも,類似した,しかし不確実なイベントが記録されています.
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