Kaib Nathan A
Department of Physics and Astronomy, University of Oklahoma, 440 W. Brooks St., Norman, OK 73019, USA. Email:
Sci Adv. 2022 Apr;8(13):eabm9130. doi: 10.1126/sciadv.abm9130. Epub 2022 Mar 30.
The discovery probability of long-period comets (LPCs) passing near the Sun is highest during their first passage and then declines, or fades, during subsequent return passages. Comet fading is largely attributed to devolatilization and fragmentation via thermal processing within 2 to 3 astronomical unit (au) of the Sun (1 au being the Earth-Sun distance). Here, our numerical simulations show that comet-observing campaigns miss vast numbers of LPCs making returning passages through the Saturn region (near 10 au) because these comets fade during prior, even more distant passages exterior to Saturn and thus elude detection. Consequently, comet properties substantially evolve at solar distances much larger than previously considered, and this offers new insights into the physical and dynamical properties of LPCs, both near and far from Earth.
长周期彗星（LPCs）在首次接近太阳时被发现的概率最高，随后在后续返回过程中该概率会下降或消失。彗星消失主要归因于在距离太阳2至3天文单位（au）（1 au为日地距离）范围内通过热处理导致的脱挥发分和破碎。在此，我们的数值模拟表明，彗星观测活动错过了大量在土星区域（约10 au）返回的长周期彗星，因为这些彗星在之前甚至更远离土星的外部区域返回时就已经消失，从而未能被发现。因此，彗星的性质在比之前认为的大得多的太阳距离处就会发生显著变化，这为深入了解长周期彗星在靠近和远离地球时的物理和动力学性质提供了新的见解。
