1996A&A...305..878G

The goal of this paper is to derive the physical properties of the dust envelopes around the post-AGB stars IRAS 10215-5916, 16342-3814, 17150-3224, and 19500-1709 by means of radiative transfer calculations. The theoretical spectral energy distributions (SEDs) have been compared with observational data for the wavelength range from 0.4 to 1300µm. We were able to obtain a very satisfactory match between our model SEDs and the observational data. As a result, we have derived estimates of the inner and outer radii, the density, the temperature, and the mass of the circumstellar shells of the four objects. For IRAS 16342-3814, 17150-3224, and 19500-1709 the emission observed at submillimetre and millimetre wavelengths can be accounted for either by a single shell and a dust emissivity that follows a power law Q_λ∝λ^–0.7 for λ≥230µm or by assuming the presence of a second shell located outwards from the shell responsible for the 10-100 µm radiation.