Rotational variation of the linear polarization of the asteroid (3200) Phaethon as evidence for inhomogeneity in its surface properties?
Rotational variation of the linear polarization of the asteroid (3200) Phaethon as evidence for inhomogeneity in its surface properties?
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小行星 (3200) Phaethon 线性偏振的旋转变化作为其表面特性不均匀性的证据？
DOI：
10.1093/mnrasl/sly140
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
Borisov G
中科院分区：
文献类型：
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作者：
Borisov G
小行星（3200）法厄同（Phaethon）是一颗近地阿波罗小行星，其轨道不同寻常，使其比任何其他已知的小行星都更接近太阳。它最后一次接近地球是在2017年12月中旬，下一次将在2026年10月。以前的旋转时间分辨光谱法表明，它的光谱斜率是稍微偏蓝，与它的B/F分类一致，但在某些旋转阶段，它改变为稍微带红色。受这一结果的启发，我们进行了时间分辨成像偏振法法厄同在其最近接近地球。Phaethon的自旋周期为3.604 h，我们发现线偏振随旋转的变化。这似乎是一个罕见的情况下，这种变化是明确发现，也是其相当大的幅度的结果。结合亮度和颜色变化以及先前报道的Arecibo雷达观测结果的新信息，我们得出结论，辉腾表面的矿物学没有变化。然而，观测到的线偏振的变化可能与不同地区或局部地形特征的表面风化层厚度的差异有关。
Asteroid (3200) Phaethon is a Near-Earth Apollo asteroid with an unusual orbit that brings it closer to the Sun than any other known asteroid. Its last close approach to the Earth was in 2017 mid-December and the next one will be on 2026 October. Previous rotationally time-resolved spectroscopy of Phaethon showed that its spectral slope is slightly bluish, in agreement with its B/F taxonomic classification, but at some rotational phases, it changes to slightly reddish. Motivated by this result, we performed time-resolved imaging polarimetry of Phaethon during its recent close approach to the Earth. Phaethon has a spin period of 3.604 h, and we found a variation of the linear polarization with rotation. This seems to be a rare case in which such variation is unambiguously found, also a consequence of its fairly large amplitude. Combining this new information with the brightness and colour variation as well as previously reported results from Arecibo radar observations, we conclude that there is no variation of the mineralogy across the surface of Phaeton. However, the observed change in the linear polarization may be related to differences in the thickness of the surface regolith in different areas or local topographic features.