The presence of a giant planet in a low-viscosity disc can create a gap edge in the disc ’ s radial density profile sharp enough to excite the Rossby Wave Instability .
This instability may evolve into dust-trapping vortices that might explain the “ banana-shaped ” features in recently observed asymmetric transition discs with inner cavities .
Previous hydrodynamical simulations of planet-induced vortices have neglected the timescale of hundreds to thousands of orbits to grow a massive planet to Jupiter-size .
In this work , we study the effect of a giant planet ’ s runaway growth timescale on the lifetime and characteristics of the resulting vortex .
For two different planet masses ( 1 and 5 Jupiter masses ) and two different disc viscosities ( \alpha =3 \times 10 ^ { -4 } and 3 \times 10 ^ { -5 } ) , we compare the vortices induced by planets with several different growth timescales between 10 and 4000 planet orbits .
In general , we find that slowly-growing planets create significantly weaker vortices with lifetimes and surface densities reduced by more than 50 \% .
For the higher disc viscosity , the longest growth timescales in our study inhibit vortex formation altogether .
Additionally , slowly-growing planets produce vortices that are up to twice as elongated , with azimuthal extents well above 180 ^ { \circ } in some cases .
These unique , elongated vortices likely create a distinct signature in the dust observations that differentiates them from the more concentrated vortices that correspond to planets with faster growth timescales .
Lastly , we find that the low viscosities necessary for vortex formation likely prevent planets from growing quickly enough to trigger the instability in self-consistent models .