Hidden power of near-infrared data for the study of young clusters: Illustrative case of RCW 38

Studies of star formation rely heavily on observations in the near-infrared, but they typically need information from other wavelengths for interpretation. We show that we can infer distances and estimate membership young stellar objects clusters independently using (ground-based) $J$, $H,$ $K_S$ broadband data alone. also a lower limit fraction sources with $2.2~\mu$m excess emission sensitivity comparable to mid-infrared space data, better resolution fewer biases. Finally, typical methods inferring masses these may produce substantially unreliable results. This method is applied young, massive cluster RCW 38, which distance 1.5 kpc $K_S$-band larger than 60\%.