从67 P的地形统计分析导出的彗星表面演化的制约因素
Constraints on cometary surface evolution derived from a statistical analysis of 67P's topography
摘要：
本文对67 P/Churyumov-Gerasimenko彗星的大尺度地形特征分布进行了统计分析。我们观察到，整个表面的累积悬崖高度分布遵循幂律，斜率等于-1.69 +-0.02。当这种分布是独立的研究每个区域，我们发现一个很好的相关性之间的斜率的幂律和轨道侵蚀率的表面。例如，北半球地形主要由100米尺度的结构所控制，而在近日点被照亮的南半球地形主要由10米尺度的地形特征所控制。我们的研究表明，目前的规模的悬崖控制不仅由物质凝聚力，但在每个地区的主导侵蚀过程。这一观察结果可以推广到其他彗星，我们认为原始核的特征是存在巨大的悬崖，累积高度幂指数等于或大于-1.5，而较老的侵蚀彗星表面的幂指数等于或小于-2.3。实际上，我们的模型表明，地形的测量提供了彗星侵蚀历史的定量评估，即其进化年龄。
英文摘要：
We present a statistical analysis of the distribution of large scale topographic features on comet 67P/Churyumov-Gerasimenko. We observe that the cumulative cliff height distribution across the surface follows a power law with a slope equal to -1.69 +- 0.02. When this distribution is studied independently for each region, we find a good correlation between the slope of the power law and the orbital erosion rate of the surface. For instance, the northern hemisphere topography is dominated by structures on the 100~m scale while the southern hemisphere topography, illuminated at perihelion, is dominated by 10~m scale terrain features. Our study suggest that the current size of a cliff is controlled not only by material cohesion but by the dominant erosional process in each region. This observation can be generalized to other comets, where we argue that primitive nuclei are characterized by the presence of large cliffs with a cumulative height power index equal to or above -1.5, while older, eroded cometary surfaces have a power index equal to or below -2.3. In effect, our model shows that a measure of the topography provides a quantitative assessment of a comet's erosional history, i.e. its evolutionary age.
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