On the wake generated by a planet in a disc

A planet of low mass orbiting in a two-dimensional gaseous disc generates a one-armed spiral wake. We explain this phenomenon as the result of constructive interference between wave modes in the disc, somewhat similar to the Kelvin wedge produced in the wake of a ship. The same feature is not expected in a three-dimensional disc with thermal stratification.
5 pages, 5 figures, to be published in MNRAS