论文标题
在B型小行星上观察到的蓝色光谱斜率的可能解释
A Possible Explanation for the Blue Spectral Slope Observed on B-type Asteroids
论文作者
论文摘要
为了更好地理解黑暗材料在碳质小行星反射率中的作用，我们进行了实验室研究，重点是量化相关的深色材料（石墨，磁铁矿和troilite）如何改变紫外线可见的和中性硅酸盐矿物质的近亲和近乎近晶体。我们发现，添加石墨，磁铁矿和troilite都使我们的脱石石样品的反射光谱变暗，并导致光谱斜率减小（变成蓝色）。这些光谱变化可能是由NM和微米大小的晶粒引起的。在紫外线可见区域中，我们发现石墨最有效地改变了光谱斜率，而在近红外的磁铁矿中，石墨是最有效的。在所研究的所有波长中，石墨是使我们的样品光谱变暗的最有效的效率。然而，观察到Troilite还改变了我们样品的斜率和反照率，表明磁铁矿和石墨引起的光谱变化可能不是唯一的。此外，我们发现混合物中的光谱斜率通常与Bennu上观察到的相比，这表明存在大量的细颗粒的深色材料（包括硫化物）中存在的硫化物可能会导致在B型小行星上发现的观察到的负（蓝色）斜坡。
In an effort to better understand the role dark material plays in the reflectance spectrum of carbonaceous asteroids, we performed laboratory studies focusing on quantifying how the addition of relevant dark material (graphite, magnetite and troilite) can alter the ultraviolet-visible and near-infrared spectrum of a neutral silicate mineral. We find that addition of graphite, magnetite and troilite all darken the reflectance spectrum of our forsterite samples and cause the spectral slope to decrease (become blue). These spectral changes can be caused by both nm- and micron-sized grains. In the ultraviolet-visible region, we find that graphite is most efficient at altering the spectral slope, while in the near-infrared, magnetite is the most efficient. At all wavelengths studied, graphite is the most efficient at darkening our sample spectrum. However, the observation that troilite also alters the slope and albedo of our samples suggests that the spectral changes caused by magnetite and graphite may not be unique. In addition, we find that the spectral slopes in our mixtures compare generally well to what has been observed on Bennu suggesting that a significant portion of fine-grained dark material, including sulfides, present in the regolith can cause the observed negative (blue) slope found on B-type asteroids.
