On the integrability of a Hamiltonian reduction of a 2+1-dimensional non-isothermal rotating gas cloud system

A 2+1-dimensional version of a non-isothermal gas dynamic system with origins in the work of Ovsiannikov and Dyson on spinning gas clouds is shown to admit a Hamiltonian reduction which is completely integrable when the adiabatic index gamma = 2. This nonlinear dynamical subsystem is obtained via an elliptic vortex ansatz which is intimately related to the construction of a Lax pair in the integrable case. The general solution of the gas dynamic system is derived in terms of Weierstrass (elliptic) functions. The latter derivation makes use of a connection with a stationary nonlinear Schrodinger equation and a Steen-Ermakov-Pinney equation, the superposition principle of which is based on the classical Lame equation.