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We model particle growth in a turbulent, viscously evolving protoplanetary nebula, incorporating sticking, bouncing, fragmentation, and mass transfer at high speeds. We treat small particles using a moments method and large particles using a traditional histogram binning, including a probability distribution function of collisional velocities. The fragmentation strength of the particles depends on their composition (icy aggregates are stronger than silicate aggregates). The particle opacity, which controls the nebula thermal structure, evolves as particles grow and mass redistributes. While growing, particles drift radially due to nebula headwind drag. Particles of different compositions evaporate at "evaporation fronts" (EFs) where the midplane temperature exceeds their respective evaporation temperatures. We track the vapor and solid phases of each component, accounting for advection and radial and vertical diffusion. We present characteristic results in evolutions lasting 2 × 10 5 years. In general, (a) mass is transferred from the outer to inner nebula in significant amounts, creating radial concentrations of solids at EFs; (b) particle sizes are limited by a combination of fragmentation, bouncing, and drift; (c) "lucky" large particles never represent a significant amount of mass; and (d) restricted radial zones just outside each EF become compositionally enriched in the associated volatiles. We point out implications for mm-submm SEDs and inference of nebula mass, radial banding, the role of opacity on new mechanisms for generating turbulence, enrichment of meteorites in heavy oxygen isotopes, variable and nonsolar redox conditions, primary accretion of silicate and icy planetesimals, and the makeup of Jupiter's core.

The streaming instability for solid particles in protoplanetary disks is reexamined assuming the familiar alpha (α) model for isotropic turbulence. Turbulence always reduces the growth rates of the streaming instability relative to values calculated for globally laminar disks. While for small values of the turbulence parameter, α < 10−5, the wavelengths of the fastest growing disturbances are small fractions of the local gas vertical scale height H, we find that for moderate values of the turbulence parameter, i.e., α ∼ 10−5–10−3, the length scales of maximally growing disturbances shift toward larger scales, approaching H. At these moderate turbulent intensities and for local particle to gas mass density ratios ϵ < 0.5, the vertical scales of the most unstable modes begin to exceed the corresponding radial scales so that the instability appears in the form of vertically oriented sheets extending well beyond the particle scale height. We find that for hydrodynamical turbulent disk models reported in the literature, with α = 4 × 10−5–5 × 10−4, together with state-of-the-art global evolution models of particle growth, the streaming instability is predicted to be viable within a narrow triangular patch of α–τ s parameter space centered on Stokes numbers, τ s  ∼ 0.01 and α ∼ 4 × 10−5, and further, exhibits growth rates on the order of several hundreds to thousands of orbit times for disks with 1% (Z = 0.01) cosmic solids abundance or metallicity. Our results are consistent with, and place in context, published numerical studies of streaming instabilities.

We present an overview of the formation of Jupiter and its associated circumplanetary disk. Jupiter forms via a combination of planetesimal accretion and gravitational accumulation of gas from the surrounding solar nebula. The formation of the circumjovian gaseous disk, or subnebula, straddles the transitional stage between runaway gas accretion and Jupiter's eventual isolation from the circumsolar disk. This isolation, which effectively signals the termination of Jupiter's accretion, takes place as Jupiter opens a deep gas gap in the solar nebula, or the solar nebula gas dissipates. The gap-opening stage is relevant to subnebula formation because the radial extent of the circumjovian disk is determined by the specific angular momentum of gas that enters Jupiter's gravitational sphere of influence. Prior to opening a well-formed, deep gap in the circumsolar disk, Jupiter accretes low specific angular momentum gas from its vicinity, resulting in the formation of a rotationally-supported compact disk whose size is comparable to the radial extent of the Galilean satellites. This process may allocate similar amounts of angular momentum to the planet and the disk, leading to the formation of an ab-initio massive disk compared to the mass of the satellites. As Jupiter approaches its final mass and the gas gap deepens, a more extended, less massive disk forms because the gas inflow, which must come from increasingly farther away from the planet's semimajor axis, has high specific angular momentum. Thus, the size of the circumplanetary gas disk upon inflow is dependent on whether or not a gap is present. We describe the conditions for accretion of the Galilean satellites, including the timescales for their formation and mechanisms for their survival, all within the context of key constraints for satellite formation models. The environment in which the regular satellites form is tied to the timescale for circumplanetary disk dispersal, which depends on the nature and persistence of turbulence. In the case that subnebula turbulence decays as gas inflow wanes, we present a novel mechanism for satellite survival involving gap opening by the largest satellites. On the other hand, assuming that sustained turbulence drives subnebula evolution on a short timescale compared to the satellite formation timescale, we review a model that emphasizes collisional processes to explain satellite observations. We briefly discuss the mechanisms by which solids may be delivered to the circumplanetary disk. At the tail end of Jupiter's accretion, most of the mass in solids resides in planetesimals of size > 1 km; however, planetesimals in Jupiter's feeding zone undergo a period of intense collisional grinding, placing a significant amount of mass in fragments < 1 km. Inelastic or gravitational collisions within Jupiter's gravitational sphere of influence allow for the mass contained in these planetesimal fragments to be delivered to the circumplanetary disk either through direct collisional/gravitational capture, or via ablation through the c...