Fine-grained rim formation via kinetic dust aggregation in shock waves around evaporating icy planetesimals

Abstract

Fine-grained rims (FGRs) are frequently found around chondrules in primitive chondrites. The remarkable feature of FGRs is their submicron-sized and non-porous nature. The typical thickness of FGRs around chondrules is 10--100 $\mu$m. Recently, a novel idea was proposed for the origin of FGRs: high-speed collisions between chondrules and fine dust grains called the kinetic dust aggregation process. Experimental studies revealed that (sub)micron-sized ceramic particles can stick to a ceramic substrate in a vacuum when the impact velocity is approximately in the range of 0.1--1 km/s. In this study, we examine the possibility of FGR formation via kinetic dust aggregation in chondrule-forming shock waves. When shock waves are created by undifferentiated icy planetesimals, fine dust grains would be released from the planetary surface due to evaporation of icy planetesimals. We consider the dynamics of chondrules behind the shock front and calculate the growth of FGRs via kinetic dust aggregation based on simple one-dimensional calculations. We found that non-porous FGRs with the thickness of 10--100 $\mu$m would be formed in shock waves around evaporating icy planetesimals.

13 pages, 7 figures. Accepted for publication in ApJ

References in corpus (8)

• Radially resolved simulations of collapsing pebble clouds in protoplanetary discs
• Chondrule destruction in nebular shocks
• The radial structure of planetary bodies formed by the streaming instability
• Compound chondrule formation in optically thin shock waves
• Thermal inertias of pebble-pile comet 67P/Churyumov-Gerasimenko
• Scattering polarization of 3-$\mu$m water-ice feature by large icy grains
• Ejection of Chondrules from Fluffy Matrices
• Aggregate Growth and Internal structures of Chondrite Parent Bodies Forming from Dense Clumps