Polymorphism in presolar Al(2)O(3) grains from asymptotic giant branch stars Journal Article uri icon

DCO ID 11121/4550-4201-2232-3234-CC

in language

  • eng

year of publication

  • 2004

abstract

  • We report microstructural and isotopic analyses of two presolar Al(2)O(3) grains. Aluminum oxide is important cosmically, because its presence has been detected in the infrared spectra of the circumstellar envelopes of O-rich asymptotic giant branch stars and because it is predicted to be the first solid to condense in these stellar environments. The two grain structures, one corundum and the other amorphous, confirm that asymptotic giant branch stars produce both phases. The variation in structure and Ti content demonstrates that Al(2)O(3) can condense in the absence of TiO(2) seed clusters but that Ti may be important in determining the crystal structure.

volume

  • 305

issue

  • 5689