出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：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;g )17F and
the 17O(p;a)14N reaction rates, respectively.
