Influence of different viscosities for h = 0.05. Top: time evolution of the accretion rate onto the planet. As the time needed for the initial mass to reach an equilibrium is highly dependent on the viscosity, gas accretion starts later for lower viscosities. Middle 1: evolution of the accretion rates as a function of the time after gas accretion is turned on. As the viscosity is lowered, the Rossby Wave Instability is triggered: for α ≲ 10⁻⁴, vortices are formed and influence the planetary gas accretion rates, explaining the oscillations in the accretion rate curves. Middle 2: evolution of the planetary mass as a function of the time after gas accretion is turned on. The dots represent the time at which the gap-opening mass is reached. Bottom: perturbed surface density at the time where gap-opening mass is reached (dot on the other panels). The gap-opening mass is defined by the mass needed to reach Σ∕Σ_unp = 0.1 (Crida et al. 2006). It is represented here by the horizontal gray dashed line.