Double-peak separation in edge-on PVs of radially extended DWs (connected dots) compared with the theoretical value for a single wind annulus on the outermost streamline (dotted curves). Left column: observed spatial separation Δr vs. theoretical Δr_th (from Eq. (12)); middle column: deprojected velocity shift ΔV ∕sin i vs. theoretical value ΔV_th∕sin i (from Eq. (13)). Right column: ratio of the apparent specific angular momentum j_obs = (Δr∕2) × (ΔV∕2sin i) to the true value on the outermost streamline, j_out = (Δr_th ∕2) × (ΔV_th∕2sin i). From top to bottom panels: the influence of varying (a) MHD solution (colour-coded) and inclination angle; (b) outermost launching radius r_out of the emitting region of the MHD DW; (c) index α of the emissivity radial power law (see Eq. (8)); and (d) spatial beamFWHM θ_b and PV cut position z_cut. All nonlabeled model parameters are fixed at their reference value: i = 87°, MHD solution = L5W17, r_out = 8 au, α = − 2, θ_b = 225 au, z_cut = 225 au, M_⋆ = 0.1 M_⊙, and r_in = 0.25 au. Datapoints for this reference case are circled in orange in each panel.