| Abstract |
Presolar grains are the condensates around evolved stars, which have survived the isotopic exchange processes in the early solar system. Alumina (Al2O3), one of the first condensates around O-rich evolved stars, is observed by infrared spectroscopy for many AGB stars and present in chondrites as presolar grains.
In order to understand the mineralogical nature of presolar alumina and the formation and evolution processes of circumstellar alumina grains, we performed systematic analyses of morphology, crystal structure, and oxygen isotopic compositions of alumina grains in unequilibrium ordinary chondrites, and dissolution experiments of alumina polymorphs |
