Fig. 2.

Grain size distributions presented by multiplying a⁴ to show the mass distribution in each logarithmic bin of the grain radius. The solid, dashed, and dot-dashed lines show the results at t = 10 Myr for Models A, B, and C (f _M = 0.4, 0.3, and 0.6), respectively. The dotted line presents the initial grain size distribution before shattering. Two grain species, (a) silicate and (b) carbonaceous dust, are shown. We also show a slope of 0.5 [i.e., n(a) ∝ a^−3.5].