  The onset of convection in the form of magneto-inertial waves in a rotating
fluid sphere permeated by a constant axial electric current is studied through
a perturbation analysis. Explicit expressions for the dependence of the
Rayleigh number on the azimuthal wavenumber are derived in the limit of high
thermal diffusivity. Results for the case of thermally infinitely conducting
boundaries and for the case of nearly thermally insulating boundaries are
obtained.
