Planet formation: Location, number, and timing.

在系外行星系统中看到的各种行星系统结构（数量、质量和位置）已经完全颠覆了我们太阳系和其他恒星周围行星形成的传统观点。不仅我们的行星最初的组装位置似乎不是我们今天的行星所在的位置，而且很可能我们的系统最初包含额外的行星体（质量与火星或更大，不包括可能的约1000个冥王星/厄里斯规模的矮行星）。这些额外的行星体要么是从系统中喷射出来的，要么被另一颗行星吸积，要么被并入太阳，或者可能潜伏在我们遥远的太阳系中（在散射盘或奥尔特云中）。这个研究项目将结合对遥远太阳系的最新观测数据和对太阳系和太阳系外行星系统轨道动力学的数值研究来解决这些问题。****** 2013-2017年CFHT望远镜上排名最高的大型项目是OSSOS：外太阳系起源调查。这个560小时的节目在海王星以外的柯伊伯带发现了834个新的海王星外天体（TNOs），使用了一种精确定量研究的方法，因为对天王星以外的天体的跟踪效率是100%。过去5年的观测工作需要获得高精度的轨道，而柯伊伯带的动力学研究需要在这些轨道上取得进展。未来5年，我们将对这个样本进行大量的理论建模，以了解以下方面的限制：(1)我们太阳系行星迁移的范围和时间；(2)巨行星形成的位置和时间，以及它们形成的小行星数量；(3)在主柯伊伯带之外寻找其他尚未见过的行星的证据。******这个研究项目还将继续研究快速变化的类地行星形成领域。在银河系中极其常见的现象（由开普勒宇宙飞船清楚地显示），恒星在0.5天文单位内的轨道上紧密地聚集着几颗超级地球行星。这些系统对行星形成的影响是巨大的；要么有可能在远离恒星的地方形成这些行星，然后在不破坏系统的情况下以某种方式迁移到观测到的轨道上，要么它们在可以看到的地方形成。这两种情况都充满了未解之谜。这个项目将继续已经开始的工作，探索这些紧密排列的系统的动态演化，随着时间的推移，探索这些行星的数量和质量的含义，因为长期的引力相互作用导致行星逐渐变得不稳定。

The variety of planetary system architectures (numbers, masses, and locations) seen in exoplantary systems has completed disrupted the traditional view of planet formation in our Solar System and around other stars. Not only are the initial assembly locations of our planets plausibly not where our planets are located today, but it is likely that our system initially contained additional planetary bodies (with the mass of Mars or larger, not counting the likely ~1000 Pluto/Eris scale dwarf planets). These additional planetary bodies were either ejected from the system, accreted by another planet, incorporated into the Sun, or could conceivably lurk unseen in our distant Solar System (in the scattering disk or Oort cloud). This research program will address these questions using a combination of fresh observational data on our distant solar system and numerical studies of orbital dynamics in our Solar System and in extra-solar planetary systems.******From 2013-2017 the highest ranked Large Program on the CFHT telescope was OSSOS: The Outer Solar System Origins Survey. This 560-hour program discovered 834 new trans-neptunian objects (TNOs) in the Kuiper Belt beyond Neptune, using an approach which allows precise quantitative study because the tracking efficiency is 100% for objects beyond Uranus. These past 5 years of observational effort were needed to acquire the high-precision orbits on which dynamical studies of the Kuiper Belt need to make progress. The next 5 years will see a great deal of theoretical modelling of this sample, to understand the constraints on (1) the extent and timing of migration of our Solar System's planets, (2) the location and timing of giant-planet formation and the planetesimal population out of which they were made, and (3) to search for evidence of other as-yet-unseen planets beyond the main Kuiper Belt. ******This research program will also continue investigation into the rapidly-changing field of terrestrial planet formation. The extremely common occurrence in the galaxy (made clear by the Kepler spacecraft) of stars with several super-Earth planets on orbits tightly packed within 0.5 AU. The implications of these systems for planet formation is enormous; either it is possible to form these planets far away from the star and then somehow migrate to their observed orbits without disrupting the system, or they form in place where they are seen. Either scenario is full of unanswered questions. This program will continue work already begun to explore the dynamical evolution of these tightly-packed systems, exploring implication for the number and masses of these planets over time as long-term gravitational interactions cause the planets to steadily become unstable.