行星系统的演化：从其在致密恒星环境的诞生到其今天的观测性质

Planetary astrophysics has developed rapidly over the last years due to the detection of thousands of exoplanets and major advances in computational astronomy. Although these have led to fascinating new discoveries, including potentially habitable worlds, the field still suffers from two major problems: (i) the formation and early evolution of planetary systems remains a mystery, and (ii) it is not known how the observed planetary systems achieved their current, sometimes inexplicable, orbital configurations. Even explaining the origin of our own Solar system is still challenging. In addition to internal evolution, an important aspect of planetary system dynamics is the effect of external perturbations. Most stars (and their planetary companions) form in or near dense stellar environments that typically dissolve within 10-50 Myr, after which their members become field stars. Some groupings evolve into globular or open clusters, in which close stellar encounters can be highly destructive to planetary systems. Now that thousands of exoplanets have been detected in the recent decade, it is important to quantify how the architecture of these planetary systems and their debris populations were shaped by the environments in which they were born and in which they lived. This proposed research project therefore aims to answer the following questions: (a) How does the birth environment of stars affect the planet formation process, both in the core accretion scenario and the disk fragmentation scenario? (b) For how long are planetary systems affected by the gravitational interactions with their siblings, and which interactions are most important? (c) How do external perturbations, such as encountering stars, external tidal fields, and wide binary companions stars affect the evolution of planetary systems? (d) What are the differences between planetary systems originating from different birth environments, and are these differences a result of variations in the planet formation process, of dynamical evolution, or both? (e) What is the fate of free-floating planets, and what are their dynamical and observational properties? (f) How different are the known planetary systems from their birth configurations, and what are the causes of the possible differences? (g) How does the dynamical evolution of planetary systems affect their stability and habitability? For how long are planets in the habitable zone actually habitable, and how do their climates change over time? These questions will be addressed with numerical experiments using our recently developed state-of-the-art software packages. Whatever the outcomes of these simulations, the results will have a deep impact on our understanding of the formation, evolution, and habitability of exoplanets. I have worked as a full-time faculty member at KIAA since 2009, with the aim of carrying out excellent research, student training, teaching, and service to the Chinese community.

行星天文学的研究存在两个主要问题：（1）行星系统的形成和早期演化仍然是个迷，（2）观测到的行星系统是怎样达到它们的轨道结构是不清楚的。量化行星系统和它们碎片的结构是怎样被它们诞生环境和生存环境所塑造的是重要的。因此这个研究项目的目标是回答以下问题：（a）行星的形成过程如何被其诞生环境所影响？（b）行星系统会被其与其它恒星的引力相互作用影响多久，哪种相互作用最重要？（c）外部扰动对行星系统演化的影响是怎样的？（d）从不同环境中诞生的行星系统有什么不同，这些不同具体是由什么导致的？（e）自由浮动行星的命运是什么，它们有什么性质？（f）已知的行星系统与其诞生时的结构有多大区别，是什么导致了这些可能的区别？（g）行星系统的动力学演化是怎样影响它们的稳定性和可居住性的？这些问题将通过数值实验来处理。无论这些模拟的结果怎样，这些结果都将深刻影响我们对系外行星形成，演化和可居住性的认识。

行星天文学的研究存在两个主要问题:(1)行星系统的形成和早期演化仍然是个迷，(2)观测 到的行星系统是怎样达到它们的轨道结构是不清楚的。量化行星系统和它们碎片的结构是怎样被它们 诞生环境和生存环境所塑造的是重要的。这个研究项目的目标是回答以下问题:(a)行星的形 成过程如何被其诞生环境所影响?(b)行星系统会被其与其它恒星的引力相互作用影响多久，哪种 相互作用最重要?(c)外部扰动对行星系统演化的影响是怎样的?(d)从不同环境中诞生的行星系 统有什么不同，这些不同具体是由什么导致的?(e)自由浮动行星的命运是什么，它们有什么性质 ?(f)已知的行星系统与其诞生时的结构有多大区别，是什么导致了这些可能的区别?(g)行星系 统的动力学演化是怎样影响它们的稳定性和可居住性的?这些问题将通过数值实验来处理。这些结果都将深刻影响我们对系外行星形成，演化和可居住性的认识。