Comparison of the temperature distributions derived with the ray-tracing inversion technique (blue dots and shaded regions) to the best-matching thermal equilibrium temperature distributions (black lines). Blue dots represent pixel values of the mid-plane temperature map derived with the ray-tracing inversion method. Shaded regions indicate the uncertainty of the mean temperature profile which we estimate as K (Sect. 5.1). All models assume OH5a dust. Best-matching scaling factors s_IRSF for the total flux of the ISRF are also indicated in each panel.