Chapter 10. Growth of Dust Grains in the Turbulent Solar Nebula

The solar nebula is considered to have evolved in a turbulent state at least during the period when interstellar cloud accreted onto the nebula. We have studied the growth of grains in this turbulent accretion solar nebula, taking account of the supply of interstellar grains due to the accretion. In case of fully developed turbulence, before the supply of interstellar grains affected the evolution of grains, the mean radius of the grains reached 1 cm about 20 to 40 times faster than in the laminar nebula and the spectrum was characterized by an n(m) ∝ m-1.31 power law. The supplied interstellar grains gave rise to new generations of grains and finally made the spectrum nearly steady in a time scale of about 3 × 104 yr. The steady spectrum is expressed roughly by n(m) ∝ m-2. With the calculated spectrum, the Rosseland mean grain opacity was computed. The initial thermal convection was found to decay within a few hundred years. We also discuss the implications of our calculations for planetesimal formation.