Thermal infrared (8-13 μm) spectra of 29 asteroids: The Cornell Mid-Infrared Asteroid Spectroscopy (MIDAS) survey
Thermal infrared (8-13 μm) spectra of 29 asteroids: The Cornell Mid-Infrared Asteroid Spectroscopy (MIDAS) survey
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DOI：
10.1016/j.icarus.2004.08.005
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发表时间：
2005-02
期刊：
影响因子：
3.2
通讯作者：
L. Lim;T. McConnochie;J. Bell;T. Hayward
中科院分区：
文献类型：
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作者：
L. Lim;T. McConnochie;J. Bell;T. Hayward
我们报告了康奈尔中红外小行星光谱(MIDAS)调查的结果，这是一个地面观测计划，旨在表征具有统计意义的小行星样本的8-13μm光谱特性，从各种可见光到近红外光谱类别。MIDAS是在Palomar天文台使用200英寸Hale望远镜上的Spectrcam-10(SC-10)光谱仪进行的。我们已经测量了29颗小行星的中红外光谱，并从我们的数据中得出了与标准热模型预测基本一致的温度估计。我们还生成了目标小行星的相对发射率光谱。我们只在一颗小行星1谷神星上发现了光谱对比度大于5%的发射率特征。我们的4个灶神星的光谱表明发射率的变化在2-3%的水平。ISO观测到的少数几颗小行星(其中六颗也包括在我们的调查中)的已公布光谱似乎显示出更强的发射率特征，很难与我们的测量结果相一致。对矿物和陨石样品的实验室研究表明，在细粒度时，中红外光谱特征的对比度大大降低。此外，近距离飞行任务还发现，433号爱神星被一层相对较厚的细粒风化层所覆盖。如果小天体一般都有这样的巨石，它们的中红外光谱特征可能是相当微妙的。这可能解释了为什么大部分MIDAS光谱没有明显的发射率变化。
We report the results of the Cornell Mid-IR Asteroid Spectroscopy (MIDAS) survey, a program of ground-based observations designed to characterize the 8–13 μm spectral properties of a statistically significant sample of asteroids from a wide variety of visible to near-IR spectral classes. MIDAS is conducted at Palomar Observatory using the Spectrocam-10 (SC-10) spectrograph on the 200-in Hale telescope. We have measured the mid-infrared spectra of twenty-nine asteroids and have derived temperature estimates from our data that are largely consistent with the predictions of the standard thermal model. We have also generated relative emissivity spectra for the target asteroids. On only one asteroid, 1 Ceres, have we found emissivity features with spectral contrast greater than 5%. Our spectrum of 4 Vesta suggests emissivity variation at the 2–3% level. Published spectra of several of the small number of asteroids observed with ISO (six of which are also included in our survey), which appeared to exhibit much stronger emissivity features, are difficult to reconcile with our measurements. Laboratory work on mineral and meteorite samples has shown that the contrast of mid-IR spectral features is greatly reduced at fine grain sizes. Moreover, the NEAR mission found that 433 Eros is covered by a relatively thick fine-grained regolith. If small bodies in general possess such regoliths, their mid-IR spectral features may be quite subtle. This may explain the evident absence of strong emissivity variation in the majority of the MIDAS spectra.