Unveiling the Earliest Stages of Planet Formation

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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.