Co-Accretion of Chondrules and Dust in the Solar Nebula

Abstract

We present a mechanism for chondrules to stick together by means of compaction of a porous dust rim they sweep up as they move through the dusty nebula gas. It is shown that dust aggregates formed out of micron-sized grains stick to chondrules, forming a porous dust rim. When chondrules collide, this dust can be compacted by means of rolling motions within the porous dust layer. This mechanism dissipates the collisional energy, compacting the rim and allowing chondrules to stick. The structure of the obtained chondrule-dust agglomerates (referred to as compounds) then consists of three phases: chondrules, porous dust, and dust that has been compacted by collisions. Subsequently, these compounds accrete their own dust and collide with other compounds. The evolution of the compound size distribution and the relative importance of the phases is calculated by a Monte Carlo code. Growth ends, and a simulation is terminated when all the dust in the compounds has been compacted. Numerous runs are performed, reflecting the uncertainty in the physical conditions at the chondrule formation time. It is found that compounds can grow by 1-2 orders of magnitudes in radius, upto dm-sizes when turbulence levels are low. However, relative velocities associated with radial drift form a barrier for further growth. Earlier findings that the dust sweep-up by chondrules is proportional to their sizes are confirmed. We contrast two scenarios regarding how this dust evolved further towards the densely packed rims seen in chondrites.

23 pages, accepted for publication in ApJ

References in corpus (7)

• Closed-form expressions for particle relative velocities induced by turbulence
• Dust coagulation in protoplanetary disks: porosity matters
• Survival of the mm-cm size grain population observed in protoplanetary disks
• Planetesimal formation via fragmentation in self-gravitating protoplanetary discs
• Dust Coagulation and Settling in Layered Protoplanetary Disks
• The Physics of Protoplanetesimal Dust Agglomerates II. Low Velocity Collision Properties
• Growing hydrodynamic modes in Keplerian accretion disks during secondary perturbations: Elliptical vortex effects

Cited by in corpus (7)

• Towards planetesimals: dense chondrule clumps in the protoplanetary nebula
• How to form planetesimals from mm-sized chondrules and chondrule aggregates
• Can dust coagulation trigger streaming instability?
• Solving the Coagulation Equation by the Moments Method
• Effect of dust grain porosity on the appearance of protoplanetary disks
• Experiments on the Photophoretic Motion of Chondrules and Dust Aggregates - Indications for the Transport of Matter in Protoplanetary Disks
• Accretion of dust by chondrules in a MHD-turbulent solar nebula