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 r(0) in the disc surface mass-density. It gives rise to exponentially growing non-axisymmetric perturbation (proportional to exp (im phi), m = 1, 2, ...) in the vicinity of r(0) 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.