Zoom-in plots of HC₃N emission for IRAS 4B (left), SK 15 (center), and IRAS 2B (right), with the same panels as shown in Fig. 7 left. The Gaussian component for each protostar is labeled accordingly. The black polygon marks the region selected as a potential streamer. The black ellipse in the bottom left corner represents the beam. For IRAS 4B, the black dashed polygon represents the region analyzed in relation to IRAS 4B2. 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. The scale bar represents a length of 2000 au. Bottom: KDE of the υ_LSR within the selected region. The black density histograms represent the KDE of the velocities within the black polygons. The dashed lines mark the υ_LSR of each protostar. The black scale bar represents a length equivalent to one beam. For IRAS 4B, the blue KDE represents the velocities within the dashed polygon.