Planet gap-opening feedback on disc thermal structure and composition

Abstract

ABSTRACT (Exo-)planets inherit their budget of chemical elements from a protoplanetary disc. The disc temperature determines the phase of each chemical species, which sets the composition of solids and gas available for planet formation. We investigate how gap structures, which are widely seen by recent disc observations, alter the thermal and chemical structure of a disc. Planet–disc interaction is a leading hypothesis of gap formation and so such changes could present a feedback that planets have on planet-forming material. Both the planet gap-opening process and the disc thermal structure are well studied individually, but how the gap-opening process affects disc thermal structure evolution remains an open question. We develop a new modelling method by iterating hydrodynamical and radiative transfer simulations to explore the gap-opening feedback on disc thermal structure. We carry out parameter studies by considering different planet locations rp and planet masses Mp. We find that for the same rp and Mp, our iteration method predicts a wider and deeper gap than the non-iteration method. We also find that the inner disc and gap temperature from the iteration method can vary strongly from the non-iteration or disc without planets, which can further influence dust-trap conditions, iceline locations, and distribution of various ices, such as H2O, CO2, and CO on large dust grains (‘pebbles’). Through that, a gap-opening planet can complicate the canonical picture of the non-planet disc C/O ratio and influence the composition of the next generation of planetesimals and planets.