Morphologies, Isotopes, Crystal Structures, and Microstructures of Presolar Al2О3 Grains: a NanoSIMS, EBSD, EDS, CL, and FIB-TEM study
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چکیده
Presolar grains are rare sub-micron-to-micron-sized components of primitive chondrites and interplanetary dust particles (IDPs), and are identified on the basis of their highly anomalous isotopic compositions [e.g., 1]. They formed around evolved stars prior to Solar System formation, and survived impact and radiation processing in the interstellar medium and early Solar System, before eventual incorporation into comets and asteroids. The grain morphology and crystal structure of presolar grains will reflect condensation conditions in circumstellar envelopes of asymptotic giant branch (AGB) stars, as well as processing in the interstellar medium (ISM) and protosolar disk. Transmission electron microscopy (TEM) studies of presolar oxide grains have been limited, however, due to their small sizes and low abundance relative to oxide grains with solar isotopic compositions [e.g., 2, 3]
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