Planet formation: Location, number, and timing.

在外行星系统中看到的行星系统结构（数量，质量和位置）的多样性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集合地点可能不是我们今天的行星所在的地方，而且我们的系统最初可能包含额外的行星体（火星或更大的质量，不包括可能的~1000冥王星/厄里斯尺度的矮行星）。 这些额外的行星体要么是从系统中弹射出来的，要么是被另一颗行星吸积的，要么是被太阳吸收的，或者可以想象的是潜伏在我们遥远的太阳系中（在散射盘或奥尔特云中）。 该研究方案将利用关于我们遥远太阳系的新观测数据和对我们太阳系和太阳系外行星系统轨道动态的数值研究来解决这些问题。 从2013年到2017年，CFHT望远镜上排名最高的大型计划是OSSOS：外太阳系起源调查。 这个560小时的项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（TNO），使用的方法可以进行精确的定量研究，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，柯伊伯带的动力学研究需要在这些轨道上取得进展。 在接下来的5年里，我们将对这个样本进行大量的理论建模，以了解（1）我们太阳系行星迁移的程度和时间，（2）巨行星形成的位置和时间以及它们所形成的小行星群，以及（3）在柯伊伯带之外寻找其他尚未发现的行星的证据。 该研究计划还将继续调查快速变化的类地行星形成领域。 在银河系中，有几颗超级地球行星在0.5 Au范围内紧密围绕的恒星非常常见（开普勒太空船清楚地表明了这一点）。 这些系统对行星形成的影响是巨大的;要么这些行星可以在远离星星的地方形成，然后以某种方式迁移到它们的观测轨道而不破坏系统，要么它们在它们被看到的地方形成。 这两种情况都充满了悬而未决的问题。 该计划将继续探索这些紧密堆积系统的动力学演化，探索随着时间的推移这些行星的数量和质量的影响，因为长期的引力相互作用导致行星稳定地变得不稳定。

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.