地球,月,火星へのストキャスティック遅い増殖
William F Bottke1, Richard J Walker, James M D Day
1Southwest Research Institute, 1050 Walnut Street, Suite 400, Boulder, CO 80302, USA. bottke@boulder.swri.edu
まとめ
プラネテシマルの後期増殖は,地上の天体における高度な siderophile 元素 (HSEs) の豊富さを説明する. 残った集団の巨大な弾丸は,これらの元素を地球,火星,月へと運びました.
科学分野:
- 惑星科学は惑星科学である.
- 地質化学 地質化学
- 天文学 (astronomy) 天文学 (astronomy) とは,天文学 (astronomy) とは,天文学 (astronomy) とは,天文学 (astronomy) とは
背景:
- 核の形成は,惑星のマントルから高度な siderophile 要素 (HSEs) を除去すると予想されます.
- 陸上の惑星 (地球,月,火星) は,核の形成にもかかわらず,予想外にも高いHSEの豊富さを示しています.
研究 の 目的:
- 陸上の惑星のマントルにおける高高度のHSEの説明として,後期増殖仮説を調査する.
- 地球,火星,月面にHSEを届けるために必要な小惑星集団の特徴を決定する.
主な方法:
- 巨大な弾丸が支配する残った小惑星集団のモデリング.
- 推論されたインパクターサイズ分布の比較と,小惑星帯内側,火星のインパクト盆地,惑星積層モデルの比較.
主要な成果:
- 大幅にコンドリティックな惑星系の後期増殖は,観測されたHSEの豊富さを説明することができます.
- 必要な累積質量:地球では地球質量の≥0.5%,火星では約10倍,月では約1200倍.
- 最大の衝突型惑星 (25003000 km) は地球の傾斜を変化させたかもしれないし,小さいもの (250300 km) は月面に水を届けたかもしれない.
結論:
- 巨大な惑星質の遅い増殖は,地上の天体におけるHSEの枯渇に統一された解決策を提供します.
- 推論されたインパクターサイズ分布は,独立した地質学および蓄積モデルと一致しています.
- 遅段階の衝撃は,傾斜の変化と水の供給を含む惑星の進化に重大な影響を及ぼしました.
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