Comet 162P/Siding Spring: A Surprisingly Large Nucleus
Comet 162P/Siding Spring: A Surprisingly Large Nucleus
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162P/赛辛斯普林彗星：一个大得惊人的核心
DOI：
10.1086/506252
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发表时间：
2006
期刊：
影响因子：
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通讯作者：
J. Adams
中科院分区：
文献类型：
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作者：
Y. Fernández;H. Campins;M. Kassis;C. Hergenrother;R. Binzel;J. Licandro;J. Hora;J. Adams
本文分析了162P/Siding Spring彗星(P/2004TU12)在2004年12月发现时的热发射。这颗彗星当时没有显示出尘埃彗发，所以我们已经采集了彗核的辐射样本。使用中红外光谱仪和成像仪的观测是在美国宇航局的红外望远镜设备上进行的，彗星的光谱能量分布的峰值在8到25μm之间。结合Campins和他的同事提供的三个显示热发射的维恩定律尾巴的近红外光谱，这些数据对彗核的表面性质提供了强有力的约束。我们发现，原子核的有效半径为6.0±0.8公里。这是已知的木星家族彗星中半径最大的彗星之一，考虑到这颗彗星是最近才被发现的，这是不寻常的。几何反照率H波段为0.059±0.023，R波段为0.037±0.014，V波段为0.034±0.013。我们还发现，162P的核几乎没有红外束，这意味着它的热惯量很小。包括所有的近红外光谱，得到的束流参数η为1.01±0.2。这一结果与其他表明彗核具有较低的热惯量和较少的红外光束的结果是一致的。如果在许多原子核中得到证实，对辐射测量的解释可能不会像人们担心的那样有问题。
We present an analysis of thermal emission from comet 162P/Siding Spring (P/2004 TU12) measured during its discovery apparition in 2004 December. The comet showed no dust coma at this time, so we have sampled emission from the comet's nucleus. Observations using the Mid-Infrared Spectrometer and Imager (MIRSI) were performed at NASA's Infrared Telescope Facility, where the peak of the comet's spectral energy distribution was observed between 8 and 25 μm. In combination with the three near-IR spectra presented by Campins and coworkers (in the companion to this paper) that show the Wien-law tail of the thermal emission, the data provide powerful constraints on surface properties of the nucleus. We find that the nucleus's effective radius is 6.0 ± 0.8 km. This is one of the largest radii known among Jupiter-family comets, which is unusual considering that the comet was discovered only recently. Its geometric albedo is 0.059 ± 0.023 in the H band, 0.037 ± 0.014 in the R band, and 0.034 ± 0.013 in the V band. We also find that the nucleus of 162P has little IR beaming, and this implies that the nucleus has low thermal inertia. Including all near-IR spectra yields a beaming parameter η of 1.01 ± 0.20. This result is in agreement with others showing that cometary nuclei have low thermal inertia and little IR beaming. If confirmed for many nuclei, the interpretation of radiometry may not be as problematic as feared.