Rossby wave instability

Rossby Wave Instability (RWI) is a concept related to astrophysical accretion discs.

In non-self-gravitating discs, for example around newly forming stars, the instability can be triggered by an axisymmetric bump, at some radius

These vortices are regions of high pressure and consequently act to trap dust particles which in turn can facilitate planetesimal growth in proto-planetary discs.

[7] The Rossby waves have the notable property of having the phase velocity opposite to the direction of motion of the atmosphere or disc in the comoving frame of the fluid.

It is related to the Papaloizou and Pringle instability;[11][12] where the wave is trapped between the inner and outer radii of a disc or torus.