Timescale of asteroid resurfacing by regolith convection resulting from the impact-induced global seismic shaking
Timescale of asteroid resurfacing by regolith convection resulting from the impact-induced global seismic shaking
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DOI：
10.1016/j.icarus.2016.02.032
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发表时间：
2015-08
期刊：
影响因子：
3.2
通讯作者：
Tomoya M. Yamada;K. Ando;T. Morota;H. Katsuragi
中科院分区：
文献类型：
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作者：
Tomoya M. Yamada;K. Ando;T. Morota;H. Katsuragi
建立了小行星通过风化层对流重新表面的模型来估计其时间尺度。在模型中，风化层对流是由撞击引起的全球地震震动驱动的。该模型由三个步骤组成：(i) 流星体的间歇性撞击，(ii) 撞击引起的全球振动（地震震动），以及 (iii) 振动引起的风化层对流。为了评估由风化层对流驱动的表面重修过程的可行性，我们将表面重修时间尺度估计为目标小行星大小的函数。在估计中，根据以前的工作假设了一组参数值。然而，其中一些（例如地震品质因数Q、地震效率η和地震频率f）非常不确定。尽管这些参数值可能取决于小行星的大小，但我们采用标准值来估计代表性行为。为了澄清参数依赖性，我们为重铺时间尺度开发了一种近似的缩放形式。根据估计结果，我们发现在大多数参数不确定范围内，基于风化层对流的表面重修时间尺度都比平均碰撞寿命短。这些参数范围在之前小型小行星研究报告的范围之内。这意味着风化层对流可能是小行星表面重塑过程的一种可能机制。
A model for the asteroid resurfacing by regolith convection is built to estimate its timescale. In the model, regolith convection is driven by the impact-induced global seismic shaking. The model consists of three steps: (i) intermittent impact of meteoroids, (ii) impact-induced global vibration (seismic shaking), and (iii) vibration-induced regolith convection. In order to assess the feasibility of the resurfacing process driven by regolith convection, we estimate the resurfacing timescale as a function of the size of a target asteroid. In the estimate, a set of parameter values is assumed on the basis of previous works. However, some of them (e.g., seismic quality factorQ, seismic efficiencyη, and seismic frequencyf) are very uncertain. Although these parameter values might depend on asteroid size, we employ the standard values to estimate the representative behavior. To clarify the parameter dependences, we develop an approximated scaling form for the resurfacing timescale. According to the estimated result, we find that the regolith-convection-based resurfacing timescale is shorter than the mean collisional lifetime in most of the parameter uncertainty ranges. These parameter ranges are within those reported by previous works for small asteroids. This means that the regolith convection can be a possible mechanism for the asteroid resurfacing process.