Integrated intensity and PV diagrams of the H₂CO emission. Top left: Spatial distribution of H₂CO emission in G351.77. The blue and magenta × markers indicate the position of the dense cores (Louvet et al. 2024), where each color represents the Cunningham et al. (2023) DCN spectral classification: single, and non-detected, respectively. Dashed gray curves indicate the positions of the dense cores that do not have identifiable velocities (non-detected). The intersection of the dashed black curves represent the center of the rotating and infalling modeled sphere (see Appendix F). Top right and bottom left: PV diagrams along the two perpendicular directions. The black contours represent the PV features produced by a rotating and infalling modeled sphere in the PV diagram.