巨大衝突により,地球のような組成の月が形成された

Robin M Canup¹

¹Planetary Science Directorate, Southwest Research Institute, 1050 Walnut Street, Suite 300, Boulder, CO 80302, USA. robin@boulder.swri.edu

Science (New York, N.Y.)

|October 19, 2012

まとめ

巨大衝突理論のシミュレーションでは,より大きな衝突物が,地球と月の同一の酸素同位体について説明できることを示しています. これにより,惑星衝突による月の形成に関する重要な課題が解決されました.

科学分野:

惑星科学は惑星科学である.
地質化学地質化学
月科学月科学月科学

背景:

巨大衝突理論では,月が初期の地球と惑星の衝突後に残骸から形成されたと説いています.
この理論に対する大きな課題は,地球と月の酸素同位体成分がほぼ同じであることです.
以前のモデルでは,衝突物質が破片円盤を支配することを示唆しており,観測された同位体類似性に矛盾していた.

研究の目的:

巨大衝突シミュレーションにおけるより大きなインパクターが,地球と月の同位体組成を調和させることができるかどうかを調査する.
インパクターが支配する円盤の予測と観測された地球と月の酸素同位体類似性の間の不一致に対処するために.

主な方法:

衝撃シミュレーションを実施し,以前より大きなインパクターサイズを使用しました.
惑星のマントルとの関係で発生した破片円盤の組成を分析した.

主要な成果:

より大きなインパクターを使ったシミュレーションで,惑星のマントルに匹敵する組成の破片ディスクが成功しました.
この結果は,地球と月の間の観測された同位体相似性と一致しています.
このモデルは,太陽共振による後続的な角運動量除去を必要とします.

結論:

より大きなインパクトは,地球の同位体シグネチャーと一致する月を形成するための実行可能なメカニズムを提供します.
これにより,巨大衝突理論に対する大きな課題が解決されました.
提案されたメカニズムは,角度運動量移転のための太陽共振のような追加のプロセスを要求します.

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