Panel (a): upper panels show the radial distance between the positions of δv_rot maximum and minimum peaks (Δr). Bottom panels show the difference between δv_rot at its maximum and minimum values (Δδv_rot). The star, triangle, and pentagon markers represent models with α = 10⁻⁴, 10⁻³, and 10⁻², respectively. The unfilled markers are eccentric cases the same as in Figures 2 and 4 shown in dashed lines. Panel (b): the fitting formula (Equation (16)) with all measured Δδv_rot in panel A. The numbers inside the symbols represent cases with different planet masses in ascending order (e.g., “1” stands for 11 M_⊕). The errorbar is shown in the upper-left corner.