Inferring plasma conditions of the primordial solar nebula from meteorite samples

The process of planet formation consists of hierarchical growth of solid bodies spanning the scales from m-sized dust to km-sized planetesimals. The growth of solids from the sub-millimeter to meter scales is a particularly poorly understood regime in this process. Meteoritic samples show that many mm-sized inclusions (chondrules) have dust coatings, known as fine-grained rims (FGRs). FGRs may play a key role in allowing chondrules to stick together to form larger bodies. The collection of a dust rim on the chondrule surface depends on nebular conditions such as ionization of the nebular gas and turbulence. Dust grains and chondrules immersed in the plasma become charged, providing a mutually repulsive force, while turbulence provides greater relative velocities between chondrules and dust. The ratio of electrostatic potential energy to kinetic energy at the point of collision affects the subsequent rim growth. Here we report on numerical models of FGR growth and restructuring designed to link the observed FGR characteristics to the nebular conditions.