从其重力场和形状推断出一个部分差异化的内部 (1)
R S Park1, A S Konopliv1, B G Bills1
1Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109, USA.
Nature
|August 4, 2016
概括
黎明号航天器发现小行星塞雷斯处于水静平衡状态,这表明其内部部分分化,内心有岩石和丰富的挥发物. 这表明天体是通过热力进化而形成的,但其大小却具有复杂的历史.
科学领域:
- * 星球科学
- * 小行星科学
- * 地质学
背景情况:
- *远程观测提供了小行星 (1) Ceres的近似密度和形状.
- 之前的车型从均到完全差异化的内饰.
- 一个关键的缺失参数,惯性时刻,内部模型受限.
研究的目的:
- * 测量塞雷斯的重力变化和惯性瞬间.
- * 为了限制塞雷斯内部结构的模型.
- * 了解塞雷斯的热和组成演变.
主要方法:
- 使用"黎明"航天器获得的重力和形状测量.
- * 分析数据以确定水静平衡和惯性瞬间.
- 使用双层模型建模内部结构.
主要成果:
- * 星球处于水立平衡状态,平均惯性矩为0.37.
- * 星球部分分化:岩石核心,外含有挥发性物质.
- * 重力信号抑制表明同静电补偿,暗示深处的低粘度层.
- *外厚度为70190公里,密度表明挥发物和岩石的混合物.
结论:
- * 塞雷斯的内部是热进化的,但它的差异化比预期的更复杂.
- * 低粘度层的存在表明热梯度而不是组成.
- 这些发现挑战了中型岩石体的简单模型.
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