Accretion and compaction of chondrule dust rims

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The present theory of our solar system’s origin involves a massive concentration of dust and gas collapsing under gravity, forming a star that is embedded in a protoplanetary disk of material from which planets, moons, asteroids, and comets form. Meteorites can provide evidence of how this dust and gas formed rocky objects in this protoplanetary disk. This laboratory and theoretical research program will address whether fine-grained-dust rims around chrondrules in stony meteorites can cause them to form larger objects, which become the building blocks of asteroids. Undergraduate students at Baylor University and at the University of Texas at Austin will be trained in modern laboratory techniques.This research will determine the initial structural properties of dust rims accreted by chondrules. A numerical dust coagulation code with enhancements with to treat ellipsoidal and charged grains will be used to determine the pre-compaction porosity, morphology, and grain alignment of chondrule at the dust grain level. The effect of collisions on fine-grained dust rims (FGRs) compaction will be calculated using the shock physics code iSALE2D modified to represent porous FGRs as a result of collisions between rimmed-chondrule or planetesimals. Numerical simulations of the passage of shock waves through material containing rimmed chondrules will be performed. The morphology, grain alignment, and porosity of FGRs in CO, CR, and CV chondrites will be measured. This experimental work will examine how FGRs form minimally altered carbonaceous chondrites using X-ray computed tomography, electron backscatter diffraction and electron Probe microanalysis. These results will be compared to the structural properties obtained in the models.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.