PRODUCTION OF²⁶Al,⁴⁴Ti, AND⁶⁰Fe IN CORE-COLLAPSE SUPERNOVAE: SENSITIVITY TO THE RATES OF THE TRIPLE ALPHA AND¹²C(α, γ)¹⁶O REACTIONS

We have studied the sensitivity to variations in the triple alpha and 12 C(α, γ) 16 O reaction rates of the production of 26 Al, 44 Ti, and 60 Fe in core-collapse supernovae (SNe). We used the KEPLER code to model the evolution of 15 M ☉ , 20 M ☉ , and 25 M ☉ stars to the onset of core collapse and simulated the ensuing SN explosion using a piston model for the explosion and an explosion energy of 1.2 × 10 51 erg. Calculations were performed for the Anders & Grevesse and Lodders abundances. Over a range of twice the experimental uncertainty, σ, for each helium-burning rate, the production of 26 Al, 60 Fe, and their ratio vary by factors of 5 or more. For some species, similar variations were observed for much smaller rate changes, 0.5σ or less. The production of 44 Ti 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.