Dr. Mamta Gulati

Compact massive objects are often surrounded by matter in a flattened disc-like configurations. Non-axisymmetric features are observed in many such discs. like Double-peak distribution of stars at the centers of galaxies like NGC4486B and M31, lopsided distribution in brightness of scattered light, warp, and clumps in the disc around ß-Pictoris. Structural and kinematic properties of such systems are correlated to their global properties. Studying the dynamics/kinematics of these discs helps to explain their structural properties and is thus of paramount importance to study evolution of such systems. We shall discuss the discs around massive central objects where the self-gravity of the disc is sufficiently weak to make the disc nearly Keplerian. Such discs can support eigenmodes that are slow in comparison to the Keplerian flow. These discs could be gaseous or particulate or both. We shall discuss the eigenvalue problem formulation for linearly perturbed discs, using the WKB formulation and the properties of non- axisymmetric modes generated.