Comparison between model solutions for diffuse dust emission SEDs calculated using different contributions of the young and old stellar populations, but preserving the total stellar luminosity. The solid line is the solution corresponding to the best fit of NGC 891, but without the bulge contribution. The dashed line corresponds to an increase in the luminosity of the young stellar population in the diffuse stellar disk by a factor of 2 and a decrease in the luminosity of the old disk stellar population by a factor of 1.68.