1109.4018 (Eike Beitz et al.)

Experimental investigation of the nebular formation of chondrule rims and the formation of chondrite parent bodies    [PDF]

Eike Beitz, Jürgen Blum, Romain Mathieu, Andreas Pack, Dominik C. Hezel

We developed an experimental setup to test the hypothesis that accretionary dust rims around chondrules formed in the solar nebula at elevated temperatures. Our experimental method allows us to form dust rims around chondrule-analogs while being levitated in an inert-gas flow. We used micrometer-sized powdered San Carlos olivine to accrete individual dust particles onto the chondrule-analog at a temperature of 1100{\deg}C. The resulting dust-rims were analyzed by means of two different techniques: one sample was investigated with non-destructive micro computer tomography, the other with a scanning electron microscope. Both methods give very similar results for the dust-rim structure and a mean dust-rim porosity of 60 percent, demonstrating that both methods are equally well suited for sample analysis. The chondrule-analog's bulk composition has no measurable effect on the accretion efficiency of the dust. We measured the chemical composition of chondrule-analog and dust-rim to check whether elemental exchange between the tow components occurred. Such a reaction zone was not found, thus we can experimentally confirm the sharp border between chondrules and dust-rims described in the literature. The experimental dust-rim porosities and reported porosities in carbonaceous and ordinary chondrites depend on the meteorite type, indicating different degrees of compaction subsequent to parent

View original: http://arxiv.org/abs/1109.4018