文章基本信息

标题：Origin and Evolution of Long-period Comets
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作者：David Vokrouhlický ; David Nesvorný ; Luke Dones 等
期刊名称：The Astronomical journal
印刷版ISSN：0004-6256
电子版ISSN：1538-3881
出版年度：2019
卷号：157
期号：5
页码：1-27
DOI：10.3847/1538-3881/ab13aa
语种：English
出版社：American Institute of Physics
摘要：We develop an evolutionary model of the long-period comet (LPC) population, starting from their birthplace in a massive trans-Neptunian disk that was dispersed by migrating giant planets. Most comets that remain bound to the solar system are stored in the Oort cloud. Galactic tides and passing stars make some of these bodies evolve into observable comets in the inner solar system. Our approach models each step in a full-fledged numerical framework. Subsequent analysis consists of applying plausible fading models and computing the original orbits to compare with observations. Our results match the observed semimajor axis distribution of LPCs when Whipple’s power-law fading scheme with an exponent 0.6 0.2 0.1 k = - + is adopted. The cumulative perihelion (q) distribution is well fit by a linear increase plus a weak quadratic term. Beyond q=15 au, however, the population increases steeply, and the isotropy of LPC orbital planes breaks. We find tentative evidence from the perihelion distribution of LPCs that the returning comets are depleted in supervolatiles and become active due to water ice sublimation for q3au. Using an independent calibration of the population of the initial disk, our predicted LPC flux is smaller than observations suggest by a factor of ;2. Current data only characterize comets from the outer Oort cloud (semimajor axes 10 4 au). A true boost in understanding the Oort cloud’s structure should result from future surveys when they detect LPCs with perihelia beyond 15 au. Our results provide observational predictions of what can be expected from these new data.
关键词：comets: general;Oort Cloud