Left: 2D histogram, ζ(M,L_IR), of mass and infrared luminosity for the Robitaille et al. (2006) YSO models with −8 < log (Ṁ_disk) < −5, integrated over all incidence angles and classified as Class I/embedded objects. The color scale is logarithmic and ranges from 0 (white) to 1000 (black) models per bin. Right: distribution of L_IR for 290 Class I, MIPSGAL YSOs linked to 219 ATLASGAL clumps in our sample.