How the planetary eccentricity influences the pebble isolation mass

Abstract

We investigate the pebble isolation mass for a planet on a fixed eccentric orbit in its protoplanetary disc by conducting a set of 2D hydrodynamical simulations including dust turbulent diffusion. A range of planet eccentricities up to $e=0.2$ is adopted. Our simulations also cover a range of $\alpha -$turbulent viscosities, and for each pair $\{\alpha ,e\}$ the pebble isolation mass is estimated as the minimum planet mass in our simulations such that solids with a Stokes number $\gtrsim 0.05$ do not flow across the planet orbit and remain trapped around a pressure bump outside the planet gap. For $\alpha <10^{-3}$, we find that eccentric planets reach a well-defined pebble isolation mass, which can be smaller than for planets on circular orbits when the eccentricity remains smaller than the disc's aspect ratio. We provide a fitting formula for how the pebble isolation mass depends on planet eccentricity. However, for $\alpha >10^{-3}$, eccentric planets cannot fully stall the pebbles flow, and thus do not reach a well-defined pebble isolation mass. Our results suggest that the maximum mass reached by rocky cores should exhibit a dichotomy depending on the disc turbulent viscosity. While being limited to $\mathcal{O}(10M_{\oplus })$ in low-viscosity discs, this maximum mass could reach much larger values in discs with a high turbulent viscosity in the planet vicinity. Our results further highlight that pebble filtering by growing planets might not be as effective as previously thought, especially in high-viscosity discs, with important implications to protoplanetary discs observations.

9 pages, 7 figures. Accepted for publication in MNRAS

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Cited by in corpus (1)

• Planet population synthesis: The role of stellar encounters