Detailed Model of the Growth of Fluffy Dust Aggregates in a Protoplanetary Disk: Effects of Nebular Conditions

Abstract

Coagulation of dust aggregates plays an important role in the formation of planets and is of key importance to the evolution of protoplanetary disks (PPDs). Characteristics of dust, such as the diversity of particle size, porosity, charge, and the manner in which dust couples to turbulent gas, affect the collision outcome and the rate of dust growth. Here we present a numerical model of the evolution of the dust population within a PPD which incorporates all of these effects. The probability that any two particles collide depends on the particle charge, cross-sectional area and their relative velocity. The actual collision outcome is determined by a detailed collision model which takes into account the aggregate morphology, trajectory, orientation, and electrostatic forces acting between charged grains. The data obtained in this research reveal the characteristics of dust populations in different environments at the end of the hit-and-stick growth, which establishes the foundation for the onset of the next growth stage where bouncing, mass transfer and fragmentation become important. For a given level of turbulence, neutral and weakly charged particles collide more frequently and grow faster than highly charged particles. However, highly charged particles grow to a larger size before reaching the bouncing barrier, and exhibit a "Runaway" growth, in which a few large particles grow quickly by accreting smaller particles while the rest of the population grows very slowly. In general, highly charged aggregates have a more compact structure and are comprised of larger monomers than neutral/weakly charged aggregates. The differences in the particle structure/composition not only affect the threshold velocities for bouncing and fragmentation, but also change the scattering and absorption opacity of dust, influencing the appearance of PPDs.

References in corpus (30)

• Closed-form expressions for particle relative velocities induced by turbulence
• The effect of dust settling on the appearance of protoplanetary disks
• Rapid Coagulation of Porous Dust Aggregates Outside the Snow Line: A Pathway to Successful Icy Planetesimal Formation
• Dust Evolution and the Formation of Planetesimals
• Fluffy dust forms icy planetesimals by static compression
• Dust coagulation in protoplanetary disks: porosity matters
• Electric charging of dust aggregates and its effect on dust coagulation in protoplanetary disks
• Accelerated planetesimal growth in self-gravitating protoplanetary discs
• Planetesimal formation around the snow line in MRI-driven turbulent protoplanetary disks
• Dust Dynamics in Compressible MHD Turbulence
• Erosion and the limits to planetesimal growth
• Electrostatic Barrier against Dust Growth in Protoplanetary Disks. I. Classifying the Evolution of Size Distribution
• Co-Accretion of Chondrules and Dust in the Solar Nebula
• Electrostatic Barrier against Dust Growth in Protoplanetary Disks. II. Measuring the Size of the "Frozen" Zone
• Efficiency of thermal relaxation by radiative processes in protoplanetary discs: constraints on hydrodynamic turbulence
• Charging and coagulation of dust in protoplanetary plasma environments
• Charging of Aggregate Grains in Astrophysical Environments
• Bouncing Behavior of Microscopic Dust Aggregates
• Signatures of MRI-Driven Turbulence in Protoplanetary Disks: Predictions for ALMA Observations
• The Physics of Protoplanetesimal Dust Agglomerates. V. Multiple Impacts of Dusty Agglomerates at Velocities Above the Fragmentation Threshold
• The 10 micron amorphous silicate feature of fractal aggregates and compact particles with complex shapes
• Giant Planet Accretion and Migration: Surviving the Type I Regime
• Effect of dust grain porosity on the appearance of protoplanetary disks
• Ionization and Dust Charging in Protoplanetary Disks
• Cosmic Dust Aggregation with Stochastic Charging
• Electron Heating in the Magnetorotational Instability: Implications for Turbulence Strength in Outer Regions of Protoplanetary Disks
• Discrete stochastic charging of aggregate grains
• Accretion of dust by chondrules in a MHD-turbulent solar nebula
• Multipole Expansions of Aggregate Charge: How Far to Go?
• The Generalized Nonlinear Ohm's Law: How a Strong Electric Field Influences Non-ideal MHD Effects in Dusty Protoplanetary Disks

Cited by in corpus (5)

• Accreting protoplanets: Spectral signatures and magnitude of gas and dust extinction at H alpha
• Formation of Comets
• Coagulation-Fragmentation Equilibrium for Charged Dust: Abundance of Submicron Grains Increases Dramatically in Protoplanetary Disks
• How leaky? A large parameter study of leaky dust traps to quantify the transport of pebbles and ice in protoplanetary discs
• The Influence of the Fractal Dimension on Dust Evolution in Protoplanetary Disks