65 Cybele in the thermal infrared: Multiple observations and thermophysical analysis
65 Cybele in the thermal infrared: Multiple observations and thermophysical analysis
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65 热红外中的 Cybele：多次观测和热物理分析
DOI：
10.1051/0004-6361:20040025
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发表时间：
2004
影响因子：
6.5
通讯作者：
J. Blommaert
中科院分区：
文献类型：
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作者：
T. G. Müller;J. Blommaert
我们研究了65 Cybele的物理和热特性，它是最大的主带小行星之一。根据已发表的和最近获得的热红外观测结果，包括ISO测量结果，我们通过热物理模型（TPM）得出了302 × 290 × 232 km（±4%）的大小和0.050 ± 0.005的几何可见光散射。我们的模型覆盖的表面具有低热惯性和“默认”粗糙度的风化层描述的波长和相位角依赖的热效应非常好。前后对射效应和光束行为可以用这种方式来解释。我们发现，在高达约100 µm的波长下，恒定的发射率为0.9，在亚毫米范围内，发射率值较低，表明粒度分布以200 µm粒度为主。光谱分析显示发射率在8.0至9.5微米之间增加。我们将这种发射率行为与碳质球粒陨石的Christiansen特征进行了比较，但无法得出结论性的鉴定。标准热模型（STM）和应用TPM之间的比较清楚地表明了STM多历元和波长观测分析的局限性和问题。虽然TPM产生了独特的直径/旋光度解决方案，但计算的STM值变化±30%，并显示出随波长和相位角的明显趋势。65 Cybele可以被认为是一个很好的教科书案例，用于结合光学和热红外观测的热物理分析。
We investigated the physical and thermal properties of 65 Cybele, one of the largest main-belt asteroids. Based on published and recently obtained thermal infrared observations, including ISO measurements, we derived through thermophys- ical modelling (TPM) a size of 302 × 290 × 232 km (±4%) and an geometric visible albedo of 0.050 ± 0.005. Our model of a regolith covered surface with low thermal inertia and "default" roughness describes the wavelengths and phase angle dependent thermal effects very well. Before/after opposition effect and beaming behaviour can be explained in that way. We found a con- stant emissivity of 0.9 at wavelengths up to about 100 µm and lower values towards the submillimetre range, indicating a grain size distribution dominated by 200 µm particle sizes. The spectroscopic analysis revealed an emissivity increase between 8.0 and 9.5 µm. We compared this emissivity behaviour with the Christiansen features of carbonaceous chondrite meteorites, but a conclusive identification was not possible. A comparison between the Standard Thermal Model (STM) and the applied TPM clearly demonstrates the limitations and problems of the STM for the analysis of multi-epoch and -wavelengths observations. While the TPM produced a unique diameter/albedo solution, the calculated STM values varied by ±30% and showed clear trends with wavelength and phase angle. 65 Cybele can be considered as a nice textbook case for the thermophysical analysis of combined optical and thermal infrared observations.