Scattering-wavelength dependence of the spatial average of the polarization degree (upper) and the polarization angle relative to the radial direction (lower) from radiative transfer simulations of a bright source with T_s = 3500 K located at the center of dusty media. These are composed of: silicates (blue triangles), graphites (yellow circles), and polycyclic aromatic hydrocarbons (green squares), as well as the BARE-GR-S dust mixture of the three compounds (Zubko et al. 2003, black stars). The shaded area indicates the optical wavelength range, and the red line indicates the peak wavelength, λ_p = 0.828 µm, of the emitting sources.