Modeling optical properties of cosmic dust grains using a distribution of hollow spheres
Modeling optical properties of cosmic dust grains using a distribution of hollow spheres
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使用空心球分布模拟宇宙尘埃颗粒的光学特性
DOI：
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发表时间：
2005
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通讯作者：
A. D. Koter
中科院分区：
文献类型：
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作者：
Michiel Min;J. Hovenier;A. D. Koter
本文研究了固体小颗粒的尺寸和形状对其吸收、发射和散射特性的综合影响。我们使用统计方法来计算这些光学性质。在这种方法中，随机方向粒子系综的平均光学性质由简单形状系综的平均光学性质表示。在中心夹杂物分数体积变化的空心球均匀分布情况下，详细研究了该方法的有效性。我们将结果应用于两个不同的感兴趣领域，i)红外光谱；ii)散射光的偏振。讨论了颗粒大小和形状对光学特性的影响。我们比较了使用空心球分布的结果和使用随机定向球的结果。我们还将结果与观测和实验室测量结果进行了比较。空心球的分布非常成功地再现了实验室测量的随机取向不规则石英颗粒入射非偏振光的线偏振度散射角分布。此外，我们表明，我们可以通过拟合测量的线极化度，利用空心球体的计算结果推导出尘埃颗粒的大小分布。结果表明，空心球的分布是研究宇宙尘埃颗粒的光散射、吸收和发射的有力工具，特别是当需要考虑大量粒子参数时，由于空心球分布的计算量很小。
In this paper we study the combined effects of size and shape of small solid state particles on the absorption, emission and scattering characteristics. We use the statistical approach to calculate these optical properties. In this approach the average optical properties of an ensemble of particles in random orientation are represented by the average optical properties of an ensemble of simple shapes. The validity of this approach is studied in detail for a uniform distribution of hollow spheres where the fractional volume of the central inclusion is varied. We apply the results to two different areas of interest, i) infrared spectroscopy; and ii) polarization of scattered light. The effects of particle size and shape on the optical characteristics are discussed. We compare the results using the distribution of hollow spheres with those obtained by using randomly oriented spheroids. Also we compare the results with observations and laboratory measurements. The distribution of hollow spheres is very successful in reproducing laboratory measurements of the scattering angle distribution of the degree of linear polarization for incident unpolarized light of randomly oriented irregular quartz particles. Furthermore, we show that we are able to derive the size distribution of dust grains by fitting the measured degree of linear polarization using computational result for hollow spheres. It is shown that the distribution of hollow spheres is a powerful tool for studying light scattering, absorption and emission by cosmic dust grains and in particular when large numbers of particle parameters need to be considered since the computational demand of the distribution of hollow spheres is small.