Comparison of our model and observation-based radial profiles for H₂O and O₂ gas fractional abundances in the IRAS 4A envelopes. Left panel: gray-scale plots (from white to black) are the radial profiles of water gas fractional abundances /n_H in the NGC 1333-IRAS 4A envelope model, which are the same as the color plots in the top right panel of Fig. 3. The red solid line shows the observational best-fit /n_H profile in the IRAS 4A envelope, obtained from van Dishoeck et al. (2021). This profile is based on analysis of Herschel/HIFI spectra which mainly trace the cold outer part (Mottram et al. 2013; Schmalzl et al. 2014), with the modification of the inner (T_gas > 100 K) water gasabundance from >10⁻⁴ to 3 × 10⁻⁶ (Persson et al. 2016). Right panel: Gray-scale plots (from white to black) are the radial profiles of molecular oxygen gas fractional abundances /n_H in the NGC 1333-IRAS 4A envelope model, which are the same as the color plots in the top right panel of Fig. 5. The model abundance profiles obtained in Yıldız et al. (2013) are over-plotted. The red solid line shows the drop gaseous O₂ abundance profile by using the C¹⁸O modeling (Yıldız et al. 2012) and assuming O₂ follows the same freeze-out and sublimation processes as C¹⁸O. The blue dashed and the green dotted lines show the gaseous O₂ abundance profiles via their gas-grain modeling with t_pre = 8 × 10⁵ yr and t_pre = 10⁶ yr, respectively. The purple arrows are to indicate that Yıldız et al. (2013) only obtained the upper limit O₂ gas abundance for this object.