Relation between stellar mass and K_s absolute magnitude of Class II source. The black dots represent the Robitaille et al. (2006) Stage 2 models with 0.001 <  M_disk/M_* <  0.01, 0.08 <  M_* <  7 M_⊙, and 30 ° < inclination angle <  60°. The red curve shows the robust polynomial fitting while the gray region shows the 1σ uncertainty of the fitting. The CTTS in L1641 from Fang et al. (2013) are marked with green filled circles.