Chandrasekhar [QJ Mech. Appl. Math. 8, 1 (1955) 10.1093/qjmam/8.1. 1] analyzed this
unstable configuration providing the equations needed to find, numerically, the exact growth
rates for the ensuing Rayleigh-Taylor instability. He also derived an analytic but approximate
solution. We point out a weakness in his approximate dispersion relation (DR) and offer a
somewhat improved one. A third DR, based on transforming a planar DR into a spherical …