Core masses vs. sizes in AG351 (blue triangles), AG354 (green squares), and AG14 (red circles). The thresholds for high-mass star formation described by Krumholz & McKee (2008), Kauffmann & Pillai (2010), and Baldeschi et al. (2017) are shown with the dashed–dotted black curve, the dashed blue curve, and the solid red line, respectively. For the last two relations we also indicated uncertainties with shaded blue and red areas, which reflect differences in the dust opacity values used here and in those works. The uncertainties on M _core are 30% (AG351 and AG354) and 38% (AG14).