Spectral reflectance properties of HED meteorites + CM2 carbonaceous chondrites: Comparison to HED grain size and compositional variations and implications for the nature of low-albedo features on Asteroid 4 Vesta
Spectral reflectance properties of HED meteorites + CM2 carbonaceous chondrites: Comparison to HED grain size and compositional variations and implications for the nature of low-albedo features on Asteroid 4 Vesta
复制标题
HED 陨石 CM2 碳质球粒陨石的光谱反射特性：与 HED 颗粒尺寸和成分变化的比较以及对小行星 4 灶神星低反照率特征性质的影响
DOI：
10.1016/j.icarus.2013.02.003
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发表时间：
2013
期刊：
影响因子：
3.2
通讯作者：
J. Bell
中科院分区：
文献类型：
--
作者：
E. Cloutis;M. Izawa;L. Pompilio;V. Reddy;H. Hiesinger;A. Nathues;P. Mann;L. Corre;E. Palomba;J. Bell
我们已经研究了光谱反射特性的CM 2捕虏体轴承howardite PRA 04401，亲密和面积的混合物的eucrite（Millbillillie）和CM 2球粒陨石（Murchison），和一个矿物多样的套件12 HED陨石。的主要目标是确定是否存在CM 2型材料可以区分从HEDs的晶粒尺寸变化。这个项目的动机是CM 2材料在一些霍华德的存在。这项研究与灶神星高度相关，因为NASA黎明号航天器上的分幅相机（FC）探测到了灶神星表面的低辐射特征。CM 2材料的加入和HED晶粒尺寸的增大都导致了总介电常数的降低。然而，这两个过程可以通过它们如何影响辉石带的深度和形状以及在较小程度上影响带的宽度来识别。辉石谱带的深度和宽度随着CM 2丰度的增加而减小，随着HED粒度的增加而增加，各种FC反射率也是如此。HED辉石的吸收谱带在晶粒尺寸为60-170μm时达到饱和，谱带Ⅰ在晶粒尺寸小于谱带Ⅱ时达到饱和。带I中心在很大程度上对CM 2丰度或HED晶粒尺寸变化不敏感，而带II中心位置随着CM 2丰度的增加而增加高达40 nm，并且作为晶粒尺寸的函数非系统地变化高达22 nm。随着CM 2丰度的变化可能是由于CM 2光谱的红色倾斜性质和辉石带II吸收的宽而浅的性质。谱带面积比显示不太一致的行为，可能是由于CM 2诱导的混合物中的斜率变化和HED中的谱带饱和效应。因为HED辉石是如此强烈的特征，所以CM 2丰度必须远远超过80 wt.%以允许其弱得多的CM 2页硅酸盐吸收带的出现。CM 2物质也可能导致光谱斜率变红，并使辉石谱带最小值向较短波长移动，尽管CM 2辉石可以表现出一定范围的光谱斜率。HED辉石中亚微米不透明（特别是铬铁矿）的存在会导致所有光谱参数的大幅变化。从HED粒度变化中区分CM 2材料的光谱改变效应是可能的，随着更大范围的光谱参数应用于分析，解释的置信度增加。
We have studied the spectral reflectance properties of the CM2 xenolith-bearing howardite PRA 04401, intimate and areal mixtures of a eucrite (Millbillillie) and a CM2 chondrite (Murchison), and a mineralogically diverse suite of 12 HED meteorites. The main goal is to ascertain whether the presence of CM2-type material can be discriminated from grain size variations in HEDs. This project was motivated by the presence of CM2 material in a number of howardites. This study is of high relevance to Vesta because of the detection of low-albedo features on its surface by the Framing Camera (FC) aboard NASA’s Dawn spacecraft. The addition of CM2 material and increasing HED grain size both lead to decreasing overall albedo. However these two processes can be recognized by how they affect pyroxene band depths and shapes and, to a lesser extent, band widths. Pyroxene band depths and widths decrease with increasing CM2 abundance and increase with increasing HED grain size, as do various FC reflectance ratios. HED pyroxene absorption bands appear to reach saturation when grain size is in the region of 60–170μm, with band I saturating at smaller grain sizes than band II. Band I centers are largely insensitive to CM2 abundances or HED grain size variations, while Band II center positions increase by up to 40nm with increasing CM2 abundance, and vary non-systematically by up to 22nm as a function of grain size. The variation with CM2 abundance is probably due to the red-sloped nature of the CM2 spectrum and the broad and shallow nature of the pyroxene band II absorption. Band area ratios show less consistent behavior, likely due to CM2-induced slope changes in the mixtures and band saturation effects in the HEDs. Because HED pyroxene is so strongly featured, CM2 abundances must be well in excess of 80wt.% to allow for the appearance of their much weaker CM2 phyllosilicate absorption bands. CM2 material may also cause a reddening of spectral slope and a shifting of pyroxene band minima to shorter wavelengths, although CM2 chondrites can exhibit a range of spectral slopes. The presence of submicron opaques (specifically chromite) in HED pyroxenes can lead to large variations in all spectral parameters. Discriminating the spectrum-altering effects of CM2 material from HED grain size variations is possible, with the confidence in the interpretation increasing as a larger range of spectral parameters are applied to the analysis.
影响因子：
2.2
作者：
Hezel, Dominik C.;Russell, Sara S.;Kearsley, Anton T.
通讯作者：
Kearsley, Anton T.
影响因子：
2.2
作者：
Barrat, J. A.;Yamaguchi, A.;Franchi, I. A.
通讯作者：
Franchi, I. A.