Radial velocity v_rad (km s⁻¹) plotted as a function of Galactic longitude l (deg). The panels a, b, c, and d show the radial velocity of a subset of the stellar content as in Fig. 10, but in a different parameter space. The vertical axis of the plots is cropped down to (−50, 50) km s⁻¹, while there are a few sources whose radial velocity can reach over 100 km s⁻¹. Within our members, only one star in US exceeds this limit at ~70 km s⁻¹. Panel a: plot of all preselected candidates with the contours showing the density. The brighter the color, the higher the density. The high density area follows a linear relation. Panel b: the radial velocity (with error bars) of the members. The subgroups are colored as in Fig. 5. The members overlap with the high density area except for a few outliers. All subgroups together form a continuous distribution, proving again that there is no incentive to separate Sco OB2 into subgroups based on a kinematical distinction. We note that most outliers are from the Halo population (gray points with error bars). Panel c: plot of the projected group model. The model points in this space are colored the same as their corresponding subgroups. The model overlays the high density area, but has a slight shift in radial velocity relative to the observations. The shift reflects the fact that our model does not use radial velocity to constrain the optimization process. Panel d: plot of the field model (red points). It separates from the high density zone just enough to generate the group-field model contrast.