Physical characteristics of cometary dust from optical studies
Physical characteristics of cometary dust from optical studies
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光学研究中彗星尘埃的物理特征
DOI：
10.1017/s0074180900066766
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发表时间：
1980
期刊：
影响因子：
--
通讯作者：
M. Hanner
中科院分区：
文献类型：
--
作者：
M. Hanner
综述了彗星尘埃的太阳光散射和热发射的观测结果，这些观测数据可以用来推断尘埃颗粒的物理性质。考虑了观测到的彗尾和彗尾散射光的波长依赖性，尘埃颗粒的平均散射函数，平均颗粒键反照率，散射光的偏振，以及由热红外发射得出的颗粒温度。对于基于磁铁矿或橄榄石颗粒材料的模型，考虑了尘埃颗粒的热物性随颗粒半径和日心距的变化，说明了尘埃颗粒的热性质。模型与观测结果的比较表明，无序或无定形的橄榄石成分可以为合适的颗粒尺寸和温度提供合理的数据拟合。所获得的观测表明，具有光学重要性的颗粒尺寸为1微米，通常存在不大于几微米的硅酸盐颗粒，尽管纯硅酸盐颗粒不可能是热发射的原因，而且彗星尘埃颗粒很可能不是球形的。指出了在红外方面还需要进一步的观测。
Observations of the sunlight scattered and thermal emission from cometary dust, which may be used to infer the physical properties of the dust grains, are reviewed. Consideration is given to the observed wavelength dependence of the scattered light from cometary coma and tails, the average scattering function of the dust grains, the average grain Bond albedo, the polarization of the scattered light, and grain temperatures deduced from thermal infrared emission. The thermal properties of dust grains are illustrated for models based on magnetite or olivine grain materials, with consideration given to the variation of thermal properties with particle radius and heliocentric distance. Comparison of the models with observations indicates that a disordered or amorphous olivine composition can give a reasonable fit to the data for appropriate grain sizes and temperatures. The observations acquired are noted to indicate an optically important particle size of 1 micron, with silicate particles not larger than a few microns usually present although pure silicate grains can not be responsible for the thermal emission, and the cometary dust grains are most likely not spherical. Further observations needed in the infrared are indicated.