Demonstration of a VSG-dominated SED. Panel a: size distribution of the two models we are comparing here: the reference model in red, which is simply the THEMIS model, with the small grains scaled down to mimic the SED of a typical ELMG; and a VSG model, in blue, which is a log-normal size distribution, peaking at 1.5 nm with a log-width of 0.2. The optical properties of the VSG model are those of THEMIS, and we have kept the same silicate-to-carbon grain mass ratio. In both cases, the curves represent the size distributions of a-C(:H) and silicates. Panel b: corresponding SEDs for the two models. The SED of the reference model has been scaled down by a factor of 0.30, to fit the VSG SED. It means the VSG SED reproduces the reference model with a dust mass 3.33 times higher. The VSG SED is uniformly illuminated by an ISRF with U = 10, while the reference model has a distribution of ISRFs with ⟨U⟩ = 200. The blue filled and red empty circles show the synthetic photometry of each model in the IRAC, MIPS1, PACS, and SPIRE bands.