Sample spectra of SO in four selected locations in Per-emb-50’s inner envelope and disk region. Left and right: Beam averaged SO spectra (green line) at positions a to d. The black solid curve represents the best fit Gaussian function. The dashed-dotted lines represent the individual Gaussians that, added together, correspond to the best fit function. Each individual color in the dashed-dotted lines represents one of the kinematic components found in Sect. 3.8: blue corresponds to the inner envelope rotation, red matches the redshifted component, brown corresponds to the gas disk, and orange matches the streamer. Middle: Integrated intensity map of SO between −1 and 14 km s⁻¹, as shown in Fig. 1, zoomed into the inner 1000 au closest to the protostar. Crosses (black and cyan) mark the locations of each spectrum, labeled a to d from highest to lowest, from right to left.