Thermo-chemical Evolution and Formation of Super-Earths and Mini-Neptunes

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It has been only 25 years since we have had evidence for planets in orbit around other stars. Over this short period of time, this new research field of exoplanets has transitioned from studying the large gaseous objects, to now focusing intensely on the low-mass exoplanets: super-Earths and mini-Neptunes. Absent from our solar system, we had not predicted their existence. However, we have evidence that such planets are the most common astrophysical objects in the Galaxy, and it is clear that they provide rich insight into an almost totally unexplored physical regime. They are the worthy subjects of current and upcoming intense observational campaigns, which means the race is on to understand the physics of these planets. Because super-Earths and mini-Neptunes are predominantly rocky, albeit the latter having a small and important gaseous atmosphere, an astronomy-only theoretical approach to studying these planets is inadequate. The complex rocky interior dominates their physical properties and is best described using geophysical principles. This is precisely the distinctive approach I bring to problem-solving, combining astrophysics and geophysics, and it is what sets me apart from most astronomers studying planets. My interdisciplinary approach lets me dive into foundational questions that are otherwise poorly solved and underpins my leadership in the study of super-Earths and mini-Neptunes. To this end, in this proposal I describe a program of investigation for my research team whose goals are to: (1) understand the range of planetary compositions that nature produces for low-mass exoplanets, (2) determine the role of giant impact collisions in shaping the composition of the low-mass planet population, (3) map the connections between atmospheric composition and interior dynamics of rocky and ocean super-Earths in order to connect observations to interior physical processes, (4) determine what sets the volatile content in a planet, and (5) understand how tidal heating affects habitability. This internationally-leading research will have tremendous impact on the astronomy and planetary science communities and will consolidate Canada's leadership in the area of exoplanets. This research field is exponentially growing and poised to produce wondrous results, while being highly-relatable to a diverse audience. The innovative research proposed here on super-Earths and mini-Neptunes, with the `made-in-Canada' seal, will attract new talent to Canadian STEM programs and captivate the public's attention.