Plume solutions for two different rates of magnetic field falloff (or flux-tube expansion). Solid curves: ν = 2 ( B ∝ r ⁻² everywhere). Dotted curves: ν = 5 ( B ∝ r ⁻⁵ for r ≲ 2.5  R _☉). As in the plume solution of Figure  2 (where ν = 4), we have set F ⁱ _g0 = F ^e _g0 = 2.5 × 10 ⁵ erg cm ⁻² s ⁻¹, H _g = 1  R _☉, F ⁱ _b0 = F ^e _b0 = 2 × 10 ⁵ erg cm ⁻² s ⁻¹, and H _b = 0.01  R _☉.