Panela: correlation between the centroid velocity of C₂H N = 1 − 0 and that of N₂H⁺ J = 1 − 0. The green solid line represents the result of linear least-squares fitting. Panel b: correlation between the line width of C₂ H N = 1 − 0 and that of N₂H⁺ J = 1 − 0. Blue dashed line represents ΔV = ΔV. Panel c: correlation between line width of C₂H N = 1 − 0 and the difference between the line width of C₂H N = 1 − 0 and that of C¹⁸O. The two dashed lines denote the 1 σ values for the distribution of line width differences. Panel d: fittings of the cumulative distribution functions of nonthermal velocities. Red and yellow solid lines show results of lognormal fittings. The three parameters (Eq. (1)) of the best lognormal fits are (0.88, 0.14, 0.20) and (0.87, 0.13, 0.16), respectively. Dashed pink lines show results of standard-normal fittings.