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arXiv 0903.4187astro-ph.EP
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距太阳5.5-4.3 AU的67 P/Churyumov-Gerasimenko彗星的Spitzer观测

Spitzer Observations of Comet 67P/Churyumov-Gerasimenko at 5.5-4.3 AU From the Sun

Michael S. Kelley, Diane H. Wooden, Cecilia Tubiana, Hermann Boehnhardt, Charles E. Woodward, David E. Harker

摘要:

我们报告斯皮策太空望远镜观测彗星67 P/Churyumov-Gerasimenko在5.5和4.3 AU从太阳,远日点后。彗星67 P是欧洲航天局罗塞塔任务的主要目标。罗塞塔号宇宙飞船将在与我们的观测结果相似的日心距离处与原子核会合。在8微米和24微米(日心距离rh为4.8天文单位)的旋转分辨观测中,对原子核的大小和色温进行了采样,并与甚大望远镜(VLT)观测到的远日点R波段光变曲线相结合,得出平均有效半径为2.04 +/- 0.11公里,R波段几何半径为0.054 +/- 0.006。R波段和中红外线曲线的振幅一致,这表明变化是由核的形状。我们还检测到彗星在4.8和5.5天文单位的尘埃轨迹,限制颗粒尺寸小于或接近6毫米,并估计影响罗塞塔的危险。我们在图像中没有发现最近喷出的尘埃的证据。如果67 P的活动在不同轨道上是一致的,那么我们可以预期罗塞塔航天器将在2014年与彗星在rh = 4 AU处会合时返回不活跃或弱活跃核的图像。

英文摘要:

We report Spitzer Space Telescope observations of comet 67P/Churyumov-Gerasimenko at 5.5 and 4.3 AU from the Sun, post-aphelion. Comet 67P is the primary target of the European Space Agency's Rosetta mission. The Rosetta spacecraft will rendezvous with the nucleus at heliocentric distances similar to our observations. Rotationally resolved observations at 8 and 24 microns (at a heliocentric distance, rh, of 4.8 AU) that sample the size and color-temperature of the nucleus are combined with aphelion R-band light curves observed at the Very Large Telescope (VLT) and yield a mean effective radius of 2.04 +/- 0.11 km, and an R-band geometric albedo of 0.054 +/- 0.006. The amplitudes of the R-band and mid-infrared light curves agree, which suggests that the variability is dominated by the shape of the nucleus. We also detect the dust trail of the comet at 4.8 and 5.5 AU, constrain the grain sizes to be less than or similar to 6 mm, and estimate the impact hazard to Rosetta. We find no evidence for recently ejected dust in our images. If the activity of 67P is consistent from orbit to orbit, then we may expect the Rosetta spacecraft will return images of an inactive or weakly active nucleus as it rendezvous with the comet at rh = 4 AU in 2014.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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