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Recent ALMA observations have found many protoplanetary discs with rings that can be explained by gap-opening planets less massive than Jupiter. Meanwhile, recent studies have suggested that protoplanetary discs should have low levels of turbulence. Past computational work on low-viscosity discs has hinted that these two developments might not be self-consistent because even low-mass planets can be accompanied by vortices instead of conventional double rings. We investigate this potential discrepancy by conducting hydrodynamic simulations of growing planetary cores in discs with various aspect ratios ($H/r=0.04$, 0.06, 0.08) and viscosities ($1.5 times 10^{-5} lesssim alpha lesssim 3 times 10^{-4}$), having these cores accrete their gas mass directly from the disc. With $alpha < 10^{-4}$, we find that sub-Saturn-mass planets in discs with $H/r le 0.06$ are more likely to be accompanied by dust asymmetries compared to Jupiter-mass planets because they can trigger several generations of vortices in succession. We also find that vortices with $H/r = 0.08$ survive $>6000$ planet orbits regardless of the planet mass or disc mass because they are less affected by the planets spiral waves. We connect our results to observations and find that the outward migration of vortices with $H/r ge 0.08$ may be able to explain the cavity in Oph IRS 48 or the two clumps in MWC 758. Lastly, we show that the lack of observed asymmetries in the disc population in Taurus is unexpected given the long asymmetry lifetimes in our low viscosity simulations ($alpha sim 2 times 10^{-5}$), a discrepancy we suggest is due to these discs having higher viscosities.
We study torques on migrating low-mass planets in locally isothermal discs. Previous work on low-mass planets generally kept the planet on a fixed orbit, after which the torque on the planet was measured. In addition to these static torques, when the
Embedded planets disturb the density structure of the ambient disk and gravitational back-reaction will induce possibly a change in the planets orbital elements. The accurate determination of the forces acting on the planet requires careful numerical
Type-II migration of giant planets has a speed proportional to the discs viscosity for values of the alpha viscosity parameter larger than 1.e-4 . At lower viscosities previous studies, based on 2D simulations have shown that migration can be very ch
Disc-driven planet migration is integral to the formation of planetary systems. In standard, gas-dominated protoplanetary discs, low-mass planets or planetary cores undergo rapid inwards migration and are lost to the central star. However, several re
Stimulated by the discovery of a number of close-in low-density planets, we generalise the Jeans escape parameter taking hydrodynamic and Roche lobe effects into account. We furthermore define $Lambda$ as the value of the Jeans escape parameter calcu