Frequency of the m = 2 fundamental mode as a function of the specific angular momentum, j, for several values of χ. The grey-shaded region illustrates the frequency range corresponding to a corotation radius located between the gain radius, r_gain, and the radius, r_BV, that maximises the Brunt–Väisälä frequency. The frequency is expressed in units of the approximate inverse advection timescale, v_sh/r_sh.