Continuity between medium size and high mass models. Top: core radius as a function of the mass, following the Simon et al. (2006b) catalogue distribution (triangles) for high masses. The red line gives the core size model adopted for high masses, when the dash red line is an estimate of the cold inner core for small masses. The black full line stands for the sum of inner core and envelope radius. Middle: associated surface brightness at 857 GHz averaged over the cold core surface including the envelope. Bottom: flux integrated over the core plus the envelope placed at a typical distance of 1 kpc.