Planet formation: Location, number, and timing.

点击翻译按钮获取中文摘要

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.