Rossby wave instability in astrophysical discs

A brief review is given of the Rossby wave instability in astrophysical discs. In non-self-gravitating discs, around for example a newly forming stars, the instability can be triggered by an axisymmetric bump at some radius r₀ in the disc surface mass-density. It gives rise to exponentially growing non-axisymmetric perturbation (\propto \exp \,({ { i}}m\phi ) , m = 1,2,…) in the vicinity of r₀ consisting of anticyclonic vortices. 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. The Rossby vortices in the discs around stars and black holes may cause the observed quasi-periodic modulations of the disc's thermal emission.