Collisional formation of top-shaped asteroids and implications for the origins of Ryugu and Bennu
Collisional formation of top-shaped asteroids and implications for the origins of Ryugu and Bennu
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DOI：
10.1038/s41467-020-16433-z
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发表时间：
2020-05-27
影响因子：
16.6
通讯作者：
Lauretta, D. S.
中科院分区：
文献类型：
--
作者：
Michel, P.;Ballouz, R-L;Lauretta, D. S.
小行星的形状和水化程度可以作为其历史和起源的示踪剂。例如，小行星（162173）Ryugu和（101955）Bennu具有明显赤道的扁球体形状，但包含不同的表面水合水平。在这里，我们表明，通过大型小行星破裂的数值模拟，扁球体，其中一些有一个明显的赤道定义一个旋转的顶部形状，可以直接通过重力再积累形成。我们进一步表明，碎石桩形成在一个单一的中断可以有类似的孔隙度，但不同程度的水化。单次破裂直接形成顶部形状可以解释Ryugu和Bennu赤道特征相对较老的陨石坑保留年龄。两个单独的母体破坏不一定需要解释他们不同的水合作用水平。小行星的形状和水化程度可以作为其历史和起源的示踪剂。在这里，作者表明，顶部形状的小行星可以通过重力再累积直接形成，而在一次破坏中形成的瓦砾堆可能具有相似的孔隙率，但水合程度不同。
Asteroid shapes and hydration levels can serve as tracers of their history and origin. For instance, the asteroids (162173) Ryugu and (101955) Bennu have an oblate spheroidal shape with a pronounced equator, but contain different surface hydration levels. Here we show, through numerical simulations of large asteroid disruptions, that oblate spheroids, some of which have a pronounced equator defining a spinning top shape, can form directly through gravitational reaccumulation. We further show that rubble piles formed in a single disruption can have similar porosities but variable degrees of hydration. The direct formation of top shapes from single disruption alone can explain the relatively old crater-retention ages of the equatorial features of Ryugu and Bennu. Two separate parent-body disruptions are not necessarily required to explain their different hydration levels. Asteroid shapes and hydration levels can serve as tracers of their history and origin. Here, the authors show top shape asteroids can form directly through gravitational reaccumulation and rubble piles formed in a single disruption can have similar porosities but variable degrees of hydration.