Collisional history of Ryugu’s parent body from bright surface boulders
Collisional history of Ryugu’s parent body from bright surface boulders
复制标题
龙宫母体与明亮表面巨石的碰撞历史
DOI：
10.1038/s41550-020-1179-z
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发表时间：
2021
期刊：
影响因子：
14.1
通讯作者：
H. ... et al. (75人中67番目)
中科院分区：
文献类型：
--
作者：
Tatsumi E.、Sugimoto C.、Riu L.、... Yabuta;H. ... et al. (75人中67番目)
小行星 (162173) Ryugu 和其他碎石堆小行星很可能是因撞击而破坏的更大母体的碎片的重新积累。然而，从原始母体到亚公里碎石堆小行星的碰撞和轨道路径尚未得到很好的了解。在这里，我们使用隼鸟2号观测结果表明，黑暗的碳质（C型）小行星龙宫上的一些明亮巨石是具有不同成分的撞击物的残余物，也是其母体的异常部分。龙宫上的明亮巨石可以分为两个光谱组：大多数没有特征，与龙宫的平均光谱相似，而另一些则显示出与普通球粒陨石一致的独特成分特征——普通球粒陨石是一类源自富含无水硅酸盐的小行星的陨石。观察到的无水硅酸盐类物质很可能是龙宫的母体与一颗或多颗富含无水硅酸盐的小行星在龙宫形成之前和形成过程中碰撞混合的结果。此外，明亮的巨石具有无特征的光谱和较少的紫外线上升，这与碳质陨石的热变质作用一致。他们可能会对不同的热变质区域进行采样，返回的样本将允许我们进行验证。因此，龙宫上的明亮巨石为亚公里碎石堆小行星的碰撞演化和积累提供了新的见解。
The asteroid (162173) Ryugu and other rubble-pile asteroids are likely re-accumulated fragments of much larger parent bodies that were disrupted by impacts. However, the collisional and orbital pathways from the original parent bodies to subkilometre rubble-pile asteroids are not yet well understood, –. Here we use Hayabusa2 observations to show that some of the bright boulders on the dark, carbonaceous (C-type) asteroid Ryugu are remnants of an impactor with a different composition as well as an anomalous portion of its parent body. The bright boulders on Ryugu can be classified into two spectral groups: most are featureless and similar to Ryugu’s average spectrum,, while others show distinct compositional signatures consistent with ordinary chondrites—a class of meteorites that originate from anhydrous silicate-rich asteroids. The observed anhydrous silicate-like material is likely the result of collisional mixing between Ryugu’s parent body and one or multiple anhydrous silicate-rich asteroid(s) before and during Ryugu’s formation. In addition, the bright boulders with featureless spectra and less ultraviolet upturn are consistent with thermal metamorphism of carbonaceous meteorites,. They might sample different thermal-metamorphosed regions, which the returned sample will allow us to verify. Hence, the bright boulders on Ryugu provide new insights into the collisional evolution and accumulation of subkilometre rubble-pile asteroids.