Northern part of Mon OB 1 east (corresponding to the yellow rectangle in Fig. 3) with the POS magnetic field orientation (blue segments), the orientations of the rotated velocity gradients (magenta segments), and intensity gradients (red segments) overlaid on the TRAO ¹²CO integrated intensity map (between v_lsr = −3 to 17 km s⁻¹) shown in panel a. In panels b–e, we show the same region. The blue shaded pattern corresponds to the regions where gravity is not dominant (case i), the red shaded pattern corresponds to the candidate collapse (case ii), the yellow shaded pattern corresponds to the candidate shock regions (case iii), overlaid on the ¹³CO integrated intensity grey scale map: (b) based on ¹²CO TRAO data smoothed to 7′ resolution, (c) based on ¹³CO TRAO data smoothed to 7′ resolution, (d) based on ¹²CO TRAO data at the resolution of 47′′, (e) based on ¹³CO TRAO data at the resolution of 47′′.