SED from the far-infrared to the radio, observed for the region outside the molecular clouds observed in CO. The fluxes observed at 160 μm and 870 μm are fitted with a single modified black-body with either an emissivity index of 1 (dashed blue line) or 2 (plain red line). Radio fluxes computed in the same regions are overplotted and the extrapolated free-free emission is displayed as a black line.