小行星（101955）Bennu上广泛分布的不同成分和形态的外生物质
Widely distributed exogenic materials of varying compositions and morphologies on asteroid (101955) Bennu
摘要：
使用OSIRIS-REx（起源，光谱解释，资源识别和安全风化层探测器）航天器上的多波段成像仪MapCam，我们确定了77个分布在B型小行星（101955）Bennu表面的外来物质。我们确定的基础上，吸收近1微米，这是无水硅酸盐的指示外生物质。外生物质的空间分辨望远镜相机PolyCam。所有这些物质都比它们的周围环境更明亮，并且它们以各种形态表达：均匀的，角砾岩状的，夹杂物状的等等。夹杂物样特征是最常见的。从MapCam图像中获得了77个位置中的46个位置的可见分光光度法。主成分分析表明，至少有两个趋势：（一）混合Bennu的平均光谱与一个强的1微米波段吸收，可能从辉石丰富的材料，和（ii）混合与一个弱的1微米波段吸收。具有强1微米特征的端元与Howardite-Eucrite-Diogenite（HED）陨石一致，而显示出弱1微米特征的端元可能与HED、普通陨石或碳质陨石一致。在几个可用的近红外反射光谱的变化强烈建议不同的成分之间的外源物质。因此，Bennu可能记录了其母体多次撞击的残留物，这些撞击可能发生在太阳系的早期历史中。此外，至少有一个外生天体的成分与在类似的小行星（162173）Ryugu上发现的外生物质不同，它们表明不同的撞击轨迹。
英文摘要：
Using the multi-band imager MapCam onboard the OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer) spacecraft, we identified 77 instances of proposed exogenic materials distributed globally on the surface of the B-type asteroid (101955) Bennu. We identified materials as exogenic on the basis of an absorption near 1 um that is indicative of anhydrous silicates. The exogenic materials are spatially resolved by the telescopic camera PolyCam. All such materials are brighter than their surroundings, and they are expressed in a variety of morphologies: homogeneous, breccia-like, inclusion-like, and others. Inclusion-like features are the most common. Visible spectrophotometry was obtained for 46 of the 77 locations from MapCam images. Principal component analysis indicates at least two trends: (i) mixing of Bennu's average spectrum with a strong 1-um band absorption, possibly from pyroxene-rich material, and (ii) mixing with a weak 1-um band absorption. The endmember with a strong 1-um feature is consistent with Howardite-Eucrite-Diogenite (HED) meteorites, whereas the one showing a weak 1-um feature may be consistent with HEDs, ordinary chondrites, or carbonaceous chondrites. The variation in the few available near-infrared reflectance spectra strongly suggests varying compositions among the exogenic materials. Thus, Bennu might record the remnants of multiple impacts with different compositions to its parent body, which could have happened in the very early history of the Solar System. Moreover, at least one of the exogenic objects is compositionally different from the exogenic materials found on the similar asteroid (162173) Ryugu, and they suggest different impact tracks.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
