Unveiling the Earliest Stages of Planet Formation

系外行星是围绕太阳系外一颗类太阳恒星运行的行星。目前的统计数据表明，银河系中几乎每一颗恒星都有一个行星系统。行星是如何在原行星盘中形成的--围绕在1000万年以下新生恒星周围的气体和尘埃盘--是天体物理学中最令人兴奋和增长最快的领域之一。根据定义，在观测中研究行星形成的最好方法是直接观察它们在圆盘中的形成。使用径向速度和凌日等传统技术探测这类行星极具挑战性。过去十年上线的新观测设施刚刚为研究行星形成提供了一种新的途径，其中仍在形成的行星的存在和性质是从引力盘-行星相互作用引起的盘结构中推断出来的。 我建议研究行星形成的最早阶段，通过研究行星诱导的结构，如旋臂、缝隙和旋涡，在解析的圆盘观测中。我使用模拟和观察来追求我的目标。在前者中，我将进行最先进的流体力学和辐射传输计算，以研究在近红外(NIR)的散射光观测和毫米/厘米波长的尘埃连续谱和气体线发射中这种结构的特征。直接可观察的特征属性(如形状、大小和对比度)与特征驱动行星的属性(如质量和轨道)之间将建立稳健和定量的关联。在后者中，我将使用詹姆斯·韦伯太空望远镜(JWST)、阿塔卡马大毫米/亚毫米阵列(ALMA)、双子座望远镜和未来的30米望远镜(TMT)等设施执行观测计划，以寻找和描述特定系统中模型预测的两颗行星以及盘状结构。将两者结合起来，我将把圆盘观测映射到数值模型，以推断在大样本系统中形成行星的性质，并在此基础上首次建立行星形成的统计数据。然后，我将根据观测到的统计数据，测试各种行星形成理论的预测，如核心吸积和引力不稳定性。 我的计划对于彻底理解行星的形成是至关重要的。它将极好地利用加拿大已经投资和获得的设施；特别是我的项目对JWST来说非常及时，计划于2019年启动，名义任务时间为5年。我将培训我的学生和博士后，学习数值模拟、图像分析，以及如何提出并进行最先进的望远镜观测。这些技能对加拿大天文学至关重要，在数据科学等私营部门需求旺盛。

An exoplanet is a planet orbits around a Sun-like star outside our solar system. The current statistics suggest that nearly every star in the Milky Way has a planetary system. How planets form in protoplanetary disks - gaseous and dusty disks surrounding newborn stars less than 10 million years old - is among the most exciting and fastest growing fields in all of astrophysics. By definition, the best way to study planet formation in observations is to directly watch them forming in disks. Detecting such planets using conventional techniques, such as radial velocity and transit, is extremely challenging. New observational facilities that came online in the last decade has just enabled a novel avenue to study planet formation, in which the presence and properties of still forming planets are inferred from disk structures induced by gravitational disk-planet interactions. I propose to investigate the earliest stages of planet formation, by studying planet-induced structures, such as spiral arms, gaps, and vortices, in resolved disk observations. I use both simulations and observations to pursue my goals. In the former, I will conduct state of the art hydrodynamics and radiative transfer calculations to study the signatures of such structures in both scattered light observations at near-infrared (NIR) and dust continuum and gas line emission at millimeter/centimeter wavelengths. Robust and quantitative correlations between feature properties that are directly observable, such as shape, size, and contrast, and properties of feature-driving planets, such as mass and orbit, will be established. In the latter, I will carry out observing programs using facilities including the James Webb Space Telescopes (JWST), the Atacama Large Millimeter/submillimeter Array (ALMA), the Gemini telescope, and the future Thirty Meter Telescope (TMT), to look for and characterize both planets predicted by models in specific systems, as well as disk structures. Combining the two, I will map disk observations to numerical models to infer the properties of forming planets in a large sample of systems, based on which I will establish the statistics of planet formation for the first time. I will then test the predictions of various planet formation theories, such as core accretion and gravitational instability, against the observed statistics. My program is of fundamental importance to a thorough understanding of planet formation. It will make excellent use of the facilities that Canada has invested in and has access to; in particular, my program is extremely timely for JWST, scheduled to be launched in 2019 with a nominal mission time of 5 years. I will train my students and postdocs in numerical simulations, image analysis, and how to propose and conduct observations on state-of-the-art telescopes. These skills are vital to Canadian astronomy, and are in heavy demand in private sectors such as data science.