New migration patterns in high planet-star mass ratio systems in disks with low viscosity

Abstract

Migration of giant planets remains a complex topic. While significant progress has been made for high-viscosity disks, the migration of planets with large planet-star mass ratios in low-viscosity environments is still not fully understood. We study the migration of such planets in disks with $\alpha =10^{-4}$ and derive analytical prescriptions applicable across stellar masses, from Sun-like stars to M dwarfs. Using hydrodynamical simulations with FARGO3D, we explored planets with mass ratios $10^{-3}<q<2\times 10^{-2}$ under different disk conditions, varying gas surface density, scale height, and density slope. Our results show a migration reversal at $q\approx 0.002$, with outward migration for $q>0.002$. For planets undergoing outward migration, the migration speed depends on the unperturbed local gas density. In most cases, outward migration is sustained by a positive torque related to planetary eccentricities below $e<0.2$. However, for certain disk parameters, planets with $q>0.01$ reach higher eccentricities ($0.2<e<0.45$), leading to stalled migration. Our findings suggest that outward migration is a viable mechanism for massive planets in low-viscosity disks, which has implications for the formation and distribution of super-Jupiter planets around Sun-like stars and planets more massive than Neptune around very low-mass stars. Given the challenges in detecting such planets, improving our theoretical understanding of their migration is essential for interpreting exoplanet demographics and guiding future observational efforts.

14 pages, 9 figures, accepted for publication in A&A

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Cited by in corpus (1)

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