小行星旋转速度在灾难性冲击中的起源
1Seismological Laboratory, California Institute of Technology, Pasadena 91125, USA. sglove@gps.caltech.edu
Nature
|March 13, 1997
概括
小行星的旋转是由碰撞控制的,对于较大的小行星来说,重力占据了材料强度的支配地位. 灾难性冲击显著改变旋转速度,与观测到的小行星旋转模式保持一致.
科学领域:
- * 星球科学 星球科学
- * 天体物理学 * 天体物理学
- * * 影响力学动态
背景情况:
- * 小行星的旋转速度取决于它们的碰撞历史.
- *以前的研究主要集中在小型撞击实验上,其中材料强度是关键.
- *最近的研究表明,重力在碰撞时会影响较大的小行星 (>1公里).
研究的目的:
- * 调查碰撞对大型,自我引力小行星的影响.
- * 模拟在对大质量物体撞击时如何保持角动量.
- * 了解控制小行星旋转演变的因素.
主要方法:
- * 对引力小行星物体的影响的数值建模.
- * 模拟灾难性碰撞,抛出大约50%的目标质量.
- *分析保留的角动量和由此产生的旋转速率.
主要成果:
- *对大型小行星的撞击结果比实验室实验更低,更可变的角度动量保留.
- *灾难性碰撞在旋转进化中占主导地位.
- * 一颗不旋转的酸盐小行星在灾难性撞击后旋转约2.9天,接近观察到的2.5天的平均值.
结论:
- *重力效应,而不是物质强度,决定了大型小行星的撞击反应.
- * 在小行星类型 (C,S,M) 中观察到的旋转速率分布与平均密度的增加相关.
- * 这个模型解释了观测到的小行星旋转速率及其分布.
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