Maximum value of the asymmetric surface brightness of resonant ring at 10 μm (blue, left axis) and the flux per beam (orange, right axis) for each spectral type, assuming a constant background level of ∼3 zodis, grain sizes of 0.1-300 μm, nulling baseline B = 100 m, and distance d = 10 pc. Higher dust levels or the inclusion of larger grains may alter the brightness and fluxes (see Sect. 4.5). Note that the two values are not in scale.