Top: results of the fitting procedure for the stellar component of M 33. The purple and orange filled circles are respectively the observed fluxes of the young and the old stellar populations presented in Table 2. The white dashed line and the gray shaded area correspond to the combination of the attenuated emission and uncertainty of the young and old stellar populations (S_ν^s,young and S_ν^s,old, respectively). For clarity, errors are only shown in the bottom panel. Bottom: residuals of the fitting procedure. The filled circles correspond to the percentage difference of the observed fluxes and the best-fitting model (white dashed line). The gray shaded area gives the uncertainty of the best-fitting model in terms of percentage.