报告题目：New observations of asteroid (4179) Toutatis as closely observed by Chang’e-2

报 告 人：季江徽 (紫金山天文台)

报告时间：12月3日（周四）下午2：00

报告地点：蒙民伟科技南楼S727

报告摘要：Toutatis, as an Apollo near-Earth asteroid in an eccentric orbit, was successfully visited by Chang'e-2 on 13 December 2012 after the spacecraft completed its lunar exploration and an extended mission of space-environment exploration at the Sun-Earth Lagrangian point. This flyby as close as a distance of 770 m away from the asteroid’s surface, reveals many geological features on Toutatis’ surface, like concavities, boulders, lineaments and regolith, particularly an ~ 800 m giant basin at the end of the large lobe as well as a sharply perpendicular silhouette near the neck region, indicating that Toutatis is probably a rubble-pile asteroid (Huang et al. 2013). We further identify more than 200 boulders over the imaged area of Toutatis, and infer that most boulders cannot solely be generated by impact cratering, but probably originate from the fragments of parent body of Toutatis (Jiang, Ji & Huang et al. 2015). Incorporation with ground-based radar observations over the last two decades, we investigate the orientation and the rotational parameters of Toutatis based on the images captured by Chang'e-2. Hence, Chang'e-2's flyby enables us to have an in-depth understanding of the formation and evolution of this asteroid.