Spectral energy distribution (SED) of I05399. The filled black circles associated with vertical error bars represent the Spitzer, IRAS, SABOCA, SCUBA, and LABOCA flux densities. The downwards pointing triangle indicates the Spitzer/IRAC 4.5-μm flux density considered as an upper limit (not taken into account in the fit). The solid black line indicates the model that gives the best fit to the input flux densities, whereas the grey line illustrates the subsequent good fit model with the criterion , where χ² is taken per data point (N_data = 13). The black dashed curve shows the SED of the stellar photosphere corresponding to the central source of the best-fitting model (as it would appear in the absence of circumstellar dust, but including the effects of interstellar dust). Note the presence of silicate absorption features at 10 and 18 μm.