2012/12/03 by R. V. E. Lovelace, R. G. Hohlfeld · 1 citation
Physics and Astronomy · #astro-ph.SR #physics.flu-dyn
paper · pdf · doi:10.1093/mnras/sts361
5 pages, 5 figures
arxiv created 2012/12/03 · arxiv updated 2015/06/12
The Rossby wave instability (RWI) in non-self-gravitating discs can be triggered by a bump at a radius r0 in the disc surface mass-density (which is proportional to the inverse potential vorticity). It gives rise to a growing non-axisymmetric perturbation [∝ exp(imϕ), m=1,2..] in the vicinity of r0 consisting of anticyclonic vortices which may facilitate planetesimal growth in protoplanetary discs. Here, we analyze a continuum of thin disc models ranging from self-gravitating to non-selfgravitating. The key quantities determining the stability/instability are: (1) the parameters of the bump (or depression) in the disc surface density, (2) the Toomre Q parameter of the disc (a non-self-gravitating disc has Q≫1), and (3) the dimensionless azimuthal wavenumber of the perturbation kϕ=mQh/r0, where h is the half-thickness of the disc. For discs stable to axisymmetric perturbations (Q>1), the self-gravity has a significant role for kϕ< π/2 or m<(π/2) (r0/h)Q-1; instability may occur for a depression or groove in the surface density if Q\lesssim 2. For kϕ> π/2 the self-gravity is not important, and instability may occur at a bump in the surface density. Thus, for all mode numbers m ≥ 1, the self-gravity is unimportant for Q > (π/2)(r0/h). We suggest that the self-gravity be included in simulations for cases where Q< (r0/h).