Igneous Ca-rich pyroxene in comet 81P/Wild 2

• DOI: 10.2138/am.2008.3048
• Publication Date: 2008-11-13T01:21:38Z
• Authors: H. Leroux; D. Jacob; J. Stodolna; K. Nakamura-Messe...; M. E. Zolensky
• Keywords: Pyroxene; Diopside; Parent body; Pigeonite; Chondrule; Asteroid belt

The Stardust spacecraft successfully returned dust from comet 81P/Wild 2 to Earth in January 2006. Preliminary examination of the samples showed abundant crystalline silicates comparable those found chondritic meteorites presumably formed asteroid belt. Here, we report results a transmission electron microscopy (TEM) study pyroxene-bearing terminal particle, which contains lamellar intergrowths pigeonite and diopside on (001) plane. This microstructure is typical for an igneous process formation by exsolution during cooling. Width wavelength lamellae indicate cooling rate within range 10-100 °C/h, close agreement with chondrules or lava asteroidal rock. observation shows that some material experienced periods processing similar inner early solar system. implies materials were common large region protoplanetary disk not restricted Their presence Wild also supports favored view radial mixing outer regions before comet’s accretion.