Unveiling the Earliest Stages of Planet Formation

系外行星是指在太阳系外围绕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，原行星盘是围绕着诞生不到1000万年的新生恒星的气体和尘埃盘，是所有天体物理学中最令人兴奋和发展最快的领域之一。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上的形成。使用径向速度和凌日等传统技术探测这类行星是极具挑战性的。在过去的十年里，新的观测设备上线了，这为研究行星的形成提供了一条新的途径，在这种途径中，仍在形成的行星的存在和性质是由引力盘-行星相互作用引起的盘结构推断出来的。*******我建议研究行星形成的最早阶段，通过研究行星引起的结构，如螺旋臂，间隙和漩涡，在解决的圆盘观测。我通过模拟和观察来实现我的目标。在前者中，我将进行最先进的流体动力学和辐射传输计算，以研究这些结构在近红外（NIR）散射光观测和毫米/厘米波长的尘埃连续体和气体线发射中的特征。将建立可直接观察到的特征属性（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）之间的鲁棒性和定量相关性。在后者中，我将使用包括詹姆斯韦伯太空望远镜（JWST），阿塔卡马大型毫米/亚毫米阵列（ALMA），双子座望远镜和未来的30米望远镜（TMT）在内的设施进行观测计划，寻找和表征特定系统中模型预测的两颗行星，以及磁盘结构。结合这两者，我将把磁盘观测映射到数值模型中，以推断在大样本系统中形成行星的特性，以此为基础，我将首次建立行星形成的统计数据。然后，我将测试各种行星形成理论的预测，如核心吸积和引力不稳定，与观察到的统计数据相对照。******我的程序对于彻底了解行星的形成是至关重要的。它将充分利用加拿大已经投资和可以使用的设施；特别是，我的计划对JWST来说非常及时，计划于2019年发射，名义任务时间为5年。我将在数值模拟、图像分析以及如何在最先进的望远镜上提出和进行观测方面训练我的学生和博士后。这些技能对加拿大天文学至关重要，并且在数据科学等私营部门需求量很大。

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.