Projected rotational velocity as a function of the 2D peculiar velocity for the 214 O-type normal (black) and runaway (blue) stars in the rotation sample. The error bars in $V_{\mathrm{PEC}}^{2\mathrm{D}}$ are the individual uncertainties of the stars computed in Carretero-Castrillo et al. (2023). The uncertainties in v sin i, not shown for clarity, are 10% of the values. The vertical dotted and solid lines indicate the usual 2D runaway threshold and the fast runaway threshold, at 25 and 85 km s⁻¹, respectively. The horizontal dashed line indicates the fast rotation threshold at 200 km s⁻¹. Top: $V_{\mathrm{PEC}}^{2\mathrm{D}}$ distribution for the normal and runaway stars with a bin size of 5 km s⁻¹. Right: v sin i distribution for the normal and runaway stars with a bin size of 20 km s⁻¹.