Isotopic composition of presolar spinel grain OC2: Constraining intermediate-mass asymptotic giant branch models

Maria Lugaro, Amanda I. Karakas, Larry R. Nittler, Conel M O D Alexander, Christian Iliadis, John C. Lattanzio

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We analyze the O, Mg, Al, Cr and Fe compositions predicted by detailed models of AGB stars of different masses and metallicities and discuss them in the light of the precise measurements of the composition of a single extraordinary presolar spinel grain, named OC2. Large excesses of the heavy Mg isotopes are present in this grain and thus an origin from an intermediate-mass (IM) asymptotic giant branch (AGB) star was previously proposed for it. Our IM-AGB models with temperatures at the base of the convective envelope ≃ 80 - 85 million degrees produce a good match to the composition of OC2 within the uncertainties related to reaction rates. This solution is possible if, in particular, we take the lower limit and the upper limit for the 16O(p,γ )17F and the 17O(p,α) 14N reaction rates, respectively.

Original languageEnglish
JournalProceedings of Science
Publication statusPublished - 1 Dec 2006
EventInternational Symposium on Nuclei in the Cosmos 2006 - Geneva, Switzerland
Duration: 25 Jun 200630 Jun 2006
Conference number: 9th

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