论文标题
一种概率的方法，用于确定CERES的平均表面成分从Dawn Vir和Grand Data确定
A probabilistic approach to determination of Ceres' average surface composition from Dawn VIR and GRaND data
论文作者
论文摘要
黎明航天器上的可见信号映射光谱仪（VIR）表明，二级矿物质（Mg-闪光体，NH4含有NH4的相位和mg/ca碳酸盐）在Ceres上无处不在。 CERES的低反射率需要黑暗相，被认为是无定形碳和/或磁铁矿（约80 wt。％）。相反，伽马射线和中子检测器（Grand）限制了C（8-14 wt。％）和Fe（15-17 wt。％）的丰度。在这里，我们将源自矿物质的矿物质与宏伟的元素组成调和。首先，我们从VIR数据中对矿物质丰度进行了建模，包括陨石来源的不溶性有机物，无定形碳，磁铁矿或组合作为变暗剂，并提供来自贝叶斯算法的统计严格误差棒，并与辐射转移模型相结合。 C和FE的元素丰度比所有满足VIR数据的模型的大观测所建议的要高得多。然后，我们表明，辐射转移模型可以预测已知组成的碳质软管的较高反射率，而不是其测得的反射率。因此，我们的第二型模型使用多个碳质软管末端成员，从而使它们的特定质地或矿物质以外的碳或磁铁矿以外的特定质地或矿物质作用为黑暗剂，包括硫化物和白云母。用碳质软管的将模型取消，消除了C和Fe的元素丰度的差异。 Ceres' average reflectance spectrum and elemental abundances are best reproduced by carbonaceous-chondrite-like materials (40-70 wt.%), IOM or amorphous carbon (10 wt.%), magnetite (3-8 wt.%), serpentine (10-25 wt.%), carbonates (4-12 wt.%), and NH4-bearing phyllosilicates (1-11 wt。％）。
The Visible-Infrared Mapping Spectrometer (VIR) on board the Dawn spacecraft revealed that aqueous secondary minerals -- Mg-phyllosilicates, NH4-bearing phases, and Mg/Ca carbonates -- are ubiquitous on Ceres. Ceres' low reflectance requires dark phases, which were assumed to be amorphous carbon and/or magnetite (~80 wt.%). In contrast, the Gamma Ray and Neutron Detector (GRaND) constrained the abundances of C (8-14 wt.%) and Fe (15-17 wt.%). Here, we reconcile the VIR-derived mineral composition with the GRaND-derived elemental composition. First, we model mineral abundances from VIR data, including either meteorite-derived insoluble organic matter, amorphous carbon, magnetite, or combination as the darkening agent and provide statistically rigorous error bars from a Bayesian algorithm combined with a radiative-transfer model. Elemental abundances of C and Fe are much higher than is suggested by the GRaND observations for all models satisfying VIR data. We then show that radiative transfer modeling predicts higher reflectance from a carbonaceous chondrite of known composition than its measured reflectance. Consequently, our second models use multiple carbonaceous chondrite endmembers, allowing for the possibility that their specific textures or minerals other than carbon or magnetite act as darkening agents, including sulfides and tochilinite. Unmixing models with carbonaceous chondrites eliminate the discrepancy in elemental abundances of C and Fe. Ceres' average reflectance spectrum and elemental abundances are best reproduced by carbonaceous-chondrite-like materials (40-70 wt.%), IOM or amorphous carbon (10 wt.%), magnetite (3-8 wt.%), serpentine (10-25 wt.%), carbonates (4-12 wt.%), and NH4-bearing phyllosilicates (1-11 wt.%).
