Zoom-in plots of N₂H⁺ emission for IRAS 4B (left), SK 15 (center), and IRAS 2B (right), with the same panels as shown in the right panel of Fig. 7 , except for SK 15. The Gaussian component for each protostar is labeled accordingly. The black ellipse in the bottom left corner represents the beam. Top: Amplitude T_MB of the Gaussian component. The blue and red arrows indicate the direction of the blue- and redshifted outflow lobes, respectively, for known outflows in the plotted area. Middle: Central velocity υ_LSR of the Gaussian component we selected. The scale bar represents a length of 2000 au. Bottom: For IRAS 4B and IRAs 2B, the position-velocity diagram along the path indicated in the top panel. For SK 15, KDE of the υ_LSR within the selected region. The red density histogram represents the KDE of the velocities within the black polygon. The dashed lines mark the υ_LSR of each protostar. The black scale bar represents a length equivalent to one beam.