Momentum of outflows from massive young stellar objects as a function of the source luminosity of the cores (Maud et al. 2015). The blue and red symbols indicate the blue- and red-shifted outflow lobe values, respectively, which are joined by a dotted line for each source. The horizontal blue-shaded range indicates the momentum of the protrusion, which is between 360 and 540 M_⊙ km s⁻¹. The cross at the bottom right shows the uncertainty for both axes.