论文标题
星际彗星2i/borisov的爆发和分裂
Outburst and Splitting of Interstellar Comet 2I/Borisov
论文作者
论文摘要
我们介绍了星际彗星2i/borisov中光度爆发和分裂事件的哈勃太空望远镜观测。爆发是由2.8 au（Drahus etal。2020）的彗星出站报道，是由在约100平方公里的横截面组合的固体颗粒驱动引起的，质量约为2e7 kg，质量为0.1 mm。后者对应于核的质量的1e-4，作为半径500 m的球体。 3月30日（爆发后约三周）观察到瞬态``双核''，其横截面约为0.6平方km，相应的灰尘质量为1E5 kg。在3月28日和之前拍摄的图像以及4月3日和之后拍摄的图像中不存在次要的。意外的延迟外观和次要的快速消失与一个或多个大（仪表大小）巨石的旋转爆发在超过扭矩的作用下，从主核中射出了扭矩。总体而言，我们的观察结果表明，细胞核的爆发和分裂是涉及总质量的小部分的次要事件：2i/borisov将在其穿过行星区域的通道中幸存下来。
We present Hubble Space Telescope observations of a photometric outburst and splitting event in interstellar comet 2I/Borisov. The outburst, first reported with the comet outbound at 2.8 AU (Drahus et al.~2020), was caused by the expulsion of solid particles having a combined cross-section about 100 sq. km and a mass in 0.1 mm sized particles about 2e7 kg. The latter corresponds to 1e-4 of the mass of the nucleus, taken as a sphere of radius 500 m. A transient ``double nucleus'' was observed on UT 2020 March 30 (about three weeks after the outburst), having a cross-section about 0.6 sq. km and corresponding dust mass 1e5 kg. The secondary was absent in images taken on and before March 28, and in images taken on and after April 03. The unexpectedly delayed appearance and rapid disappearance of the secondary are consistent with an origin through rotational bursting of one or more large (meter-sized) boulders under the action of outgassing torques, following their ejection from the main nucleus. Overall, our observations reveal that the outburst and splitting of the nucleus are minor events involving a negligible fraction of the total mass: 2I/Borisov will survive its passage through the planetary region largely unscathed.
