Illustration of the heated region in the vicinity ofthe companion for three different stellar separations. The dashed line corresponds to the τ = 1-layer as seen from the observer who is located perpendicular to the disk midplane, i.e. approximately the region where the detected flux is emitted. The companions are shown as black points on the midplane of the disk. The heated regions due to the radiation of the companion are shown as coloured circles, where blue is the hottest region, redthe coolest and purple is in between. As the optical depth decreases for increasing distance, the region heated by the embedded companion becomes larger. Therefore the photon energy is distributed over more dustparticles and the temperature increase is less than for smaller stellar separations. At the same time, the region which is significantly affected by the heating ofthe embedded companion approaches the τ = 1-layer and eventually exceeds this layer, see Fig. 6. The thermal radiation of that hot dust may then leave the disk towards the observer less weakened compared to regions below the τ = 1-layer.