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The fate of accreting luminous planets born at pressure bumps

Presentation #500.01 in the session Origin of Planetary Systems (Oral Presentation)

Published onOct 23, 2023
The fate of accreting luminous planets born at pressure bumps

Ring-like substructures observed in protoplanetary disks are often interpreted as dust concentrations located at radial pressure bumps. It has been hypothesized that these pressure bumps act as efficient factories for forming protoplanets. One supporting argument is that they can trap low-mass planets by facilitating a local balance between the disk-driven Lindblad and corotation torques, thus keeping the planets embedded within the abundant reservoir of small solids. We investigate whether this migration trap persists when accounting for thermal torques, which become particularly important when the planet accretes solids and releases the accretion heat into its surroundings. To this end, we conduct 3D radiative hydrodynamic simulations with a very large resolution (~0.8 billion grid cells). Our simulations show that if the planetary accretion luminosity exceeds the threshold predicted by the linear theory of thermal torques, the most common outcome is that the planet’s orbital eccentricity becomes excited, the corotation and thermal torques are quenched, and the Lindblad torque prevails. The latter is negative, leading to the planet escaping the pressure bump through inward migration (towards the star). Additionally, we confirm that supercritical luminosities are likely to be achieved within the pebble accretion paradigm. In summary, our findings provide evidence that thermal torques play an important role in the evolution of planets born at pressure bumps. We propose that pressure bumps are more likely to repeatedly spawn inward-migrating low-mass protoplanets rather than to harbor a single embryo until it becomes massive.

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