Exploring the Effect of Planet-Disk Interaction on Exoplanetary Atmospheres

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Compositions of exoplanetary atmospheres encode the planet's formation history. Within a spinning disk of gas and dust that surround a young star, the dust grains coagulate into rocks as massive as a few Earth masses and these massive rocks build atmospheres by gravitationally attracting the surrounding gas. The chemical composition of both the grains and the gas is expected to change drastically with location, depending on the structure of the disk. Characterizing the elemental ratio of planets can inform where in the disk the planet has assembled. Such inference requires solid understanding of the varying elemental abundance in both solid and gaseous form at different locations of a disk. The current state-of-the-art is to compute the location of phase transitions of several volatile species such as water and carbonaceous oxides by evolving the underlying disk, independent of the planets that form within them. However, planets are known to perturb the disk significantly carving out gaps and establishing traps of dust grains, interior to which the gas may be more pristine than previously thought. We propose to quantify the effect of planet-disk interactions on the exoplanetary atmospheres. In particular, through a combination of numerical hydrodynamic calculations using an open-source code ATHENA++ and semi-analytic models, we aim to 1) determine the efficiency at which the dust grains of varying sizes could be trapped by planet-driven pressure bumps; 2) track the coagulation of these trapped dust into secondary planets thereby investigating the effect of multi-planetary dynamics in setting the disk composition; 3) translate the trajectory of grains in these perturbed disks into chemical evolution of volatiles and refractory species; and to 4) build a model that evolves in time the degree of post-formation pollution in the upper atmospheres of planets. Using these insights, we will fill in the current knowledge gap connecting the evolution of protoplanetary disks as they are perturbed by the planets that emerge within them with the observable trends in studies of exoplanetary atmospheres that can be tested with the new James Webb Space Telescope and the upcoming space mission Ariel.