Comparison between the IRS (black lines) and the synthetic (red) spectra of a few sources in the LMC sample of carbon stars, with various luminosities and degrees of obscuration. The values of luminosities and τ₁₀ reported in each panel are those allowing the best fit, corresponding to the red lines. The cyan lines indicate the synthetic SED entering the carbon condensation zone, resulting from the absorption of the radiation from the photosphere by SiC particles in the innermost region of the circumstellar envelope.