Production of 26Al, 44Ti, and 60Fe in Core-Collapse Supernovae: Sensitivity to the Rates of the Triple Alpha and 12C(a,g)16O Reactions

We have studied the sensitivity to variations in the the triple alpha and 12C(a,g)16O reaction rates of the production of 26Al, 44Ti, and 60Fe in core-collapse supernovae. We used the KEPLER code to model the evolution of 15, 20, and 25 solar mass stars to the onset of core collapse and simulated the ensuing supernova explosion using a piston model for the explosion. Calculations were performed for the Anders and Grevesse (1989) and Lodders (2003) abundances. Over a range of twice the experimental uncertainty, sigma, for each helium-burning rate, the production of 26Al, 60Fe, and their ratio vary by factors of five or more. For some species, similar variations were observed for much smaller rate changes, 0.5 sigma or less. The production of 44Ti was less sensitive to changes in the helium-burning rates. Production of all three isotopes depended on the solar abundance set used for the initial stellar composition.