Value of β, the ratio between radiation pressure and gravitational forces, as a function of particle size, computed for non-porous astrosilicates. The β(s) curve is shown for the luminous A6V star considered as a reference case in our runs, as well as for the TYC 8241 2652 1 K star discussed in Sect. 4.4. The dotted horizontal line marks the β = 0.5 limit, above which grains are no longer on bound orbits around the star (if produced from progenitors on circular orbits).