The initial structure of chondrule dust rims I: electrically neutral grains

Abstract

In order to characterize the early growth of fine-grained dust rims (FGRs) that commonly surround chondrules, we perform numerical simulations of dust accretion onto chondrule surfaces. We employ a Monte Carlo algorithm to simulate the collision of dust monomers having radii between 0.5 and 10 $\mu$m with chondrules whose radii are between 500 and 1000 $\mu$m, in 100-$\mu$m increments. The collisions are driven by Brownian motion and solar nebula turbulence. After each collision, the colliding particles either stick at the point of contact, roll or bounce. We limit accretion of dust monomers (and in some cases, dust aggregates) to a small patch of the chondrule surface, for computational expediency. We model the morphology of the dust rim and the trajectory of the dust particle, which are not considered in most of the previous works. Radial profiles of FGR porosity show that rims formed in weak turbulence are more porous (with a porosity of 60-74\%) than rims formed in stronger turbulence (with a porosity of 52-60\%). The lower end of each range corresponds to large chondrules and the upper end to small chondrules, meaning that the chondrule size also has an impact on FGR porosity. The thickness of FGRs depends linearly on chondrule radius, and the slope of this linear dependency increases with time, and decreases with the turbulence strength. The porosity of FGRs formed by dust aggregates is $\sim 20\%$ on average greater than that of FGRs formed by single monomers. In general, the relatively high porosities that we obtain are consistent with those calculated by previous authors from numerical simulations, as well as with initial FGR porosities inferred from laboratory measurements of rimmed chondrule samples and rimmed chondrule analogs.

arXiv comment25 pages, 22 figures

References in corpus (18)

• The outcome of protoplanetary dust growth: pebbles, boulders, or planetesimals? I. Mapping the zoo of laboratory collision experiments
• Wind-driven Accretion in Protoplanetary Disks. I: Suppression of the Magnetorotational Instability and Launching of the Magnetocentrifugal Wind
• Closed-form expressions for particle relative velocities induced by turbulence
• The effect of dust settling on the appearance of protoplanetary disks
• How to form planetesimals from mm-sized chondrules and chondrule aggregates
• Dust coagulation in protoplanetary disks: porosity matters
• Accelerated planetesimal growth in self-gravitating protoplanetary discs
• Numerical Modeling of the Coagulation and Porosity Evolution of Dust Aggregates
• Planetesimal formation around the snow line in MRI-driven turbulent protoplanetary disks
• Hall-effect Controlled Gas Dynamics in Protoplanetary Disks: I. Wind Solutions at the Inner Disk
• Chondrule size and related physical properties: a compilation and evaluation of current data across all meteorite groups
• Erosion and the limits to planetesimal growth
• Co-Accretion of Chondrules and Dust in the Solar Nebula
• Charging and coagulation of dust in protoplanetary plasma environments
• The Physics of Protoplanetesimal Dust Agglomerates. V. Multiple Impacts of Dusty Agglomerates at Velocities Above the Fragmentation Threshold
• Giant Planet Accretion and Migration: Surviving the Type I Regime
• Accretion of dust by chondrules in a MHD-turbulent solar nebula
• Chondrule formation via extended winds in the early solar system

Cited by in corpus (6)

• Compound chondrule formation in optically thin shock waves
• Fine-grained rim formation -- high speed, kinetic dust aggregation in the early Solar System
• Formation of rims around chondrules via porous aggregate accretion
• Aggregate Growth and Internal structures of Chondrite Parent Bodies Forming from Dense Clumps
• Dependence of the initial internal structure of chondrule rim on dust size distribution
• Fine-grained rim formation via kinetic dust aggregation in shock waves around evaporating icy planetesimals