SPITZER OBSERVATIONS OF COMET 67P/CHURYUMOV-GERASIMENKO AT 5.5–4.3 AU FROM THE SUN
SPITZER OBSERVATIONS OF COMET 67P/CHURYUMOV-GERASIMENKO AT 5.5–4.3 AU FROM THE SUN
复制标题
距太阳 5.5–4.3 天文单位的斯皮策彗星 67P/Churyumov-Gerasimenko 观测
DOI：
10.1088/0004-6256/137/6/4633
复制
发表时间：
2009
期刊：
影响因子：
--
通讯作者：
D. Harker
中科院分区：
文献类型：
--
作者：
M. Kelley;D. Wooden;C. Tubiana;H. Boehnhardt;C. Woodward;D. Harker
我们报道了斯皮策太空望远镜在太阳远日点后5.5和4.3AU处对67P/Churyumov-Gerasimenko彗星的观测。67P彗星是欧洲航天局罗塞塔任务的主要目标。与我们的观测结果类似，罗塞塔号宇宙飞船将在日心距离与原子核会合。在8和24μm(日心距离，Rh，4.8AU)的旋转分辨观测采样了原子核的大小和色温，与甚大望远镜观测到的远日点R波段光曲线相结合，得到了平均有效半径为2.04±0.11公里，R波段几何反照率为0.054±0.006。R波段和中红外光曲线的幅度一致，这表明这种变化是由原子核的形状决定的。我们还在4.8AU和5.5AU探测到了彗星的尘埃轨迹，将其粒度限制在≲6 mm，并估计了对罗塞塔的撞击危险。在我们的图像中，我们没有发现最近喷出的尘埃的证据。如果67P的活动从一个轨道到另一个轨道是一致的，那么我们可以预期Rosetta航天器将在2014年与这颗彗星在Rh=4AU会合时传回一个不活跃或弱活跃的核的图像。
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 μm (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 ≲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.