¹³CO, CH₃ OH (v = 0,1), and SO₂ integrated emission and PV diagrams. Left panels: emission integrated over 10 km s⁻¹ centred on the systemic velocity. White dashed circles denote the FWHM of 2D Gaussian fits to the emission, while the red dashed lines indicate the direction and width of the PV cuts. The same PV cut is used in all panels. Synthesizedbeams are shown in the lower left corners. Right panels: resulting PV diagrams. Blue dots denote the location of emission peaks at a particular velocity (only velocity channels where the coefficient of determination, R², is larger than 0.3 are included). A linear fit to the peak emission velocity profile is represented by the blue line. Pure free-fall and pure Keplerian rotation velocities towards/around a 0.05 M_⊙ protostar are indicated in the right panels by the green and red dashed lines, respectively.