Product of the mass-loss rate with the wind speed vs. grain size for the likeliest values of β obtained in our simulations. The gray areas correspond to the dispersion of β in the orbiting cases. For simplicity, our assumed value of wind speed of 450 km s^-1 is labeled V_{sw, ⊙}. The colored vertical lines indicate, for each observing wavelength, the range of grain sizes corresponding to the smallest grains that efficiently scatter light (s ~ λ/ 2π) and which should dominate the flux for any “non-exotic” grain size distribution in the clumps (see Sect. 4.3 for details).