We investigate effects of triple- \alpha and ^ { 12 } C ( \alpha, \gamma ) ^ { 16 } O reaction rates on the production of supernova yields for a massive star of 25 M _ { \odot } .
We combine the reaction rates to examine the rate dependence , where the rates are considered to cover the possible variation of the rates based on experiments on the earth and theories .
We adopt four combinations of the reaction rates from two triple- \alpha reaction rates and two ^ { 12 } C ( \alpha, \gamma ) ^ { 16 } O ones .
First , we examine the evolution of massive stars of 20 and 25 M _ { \odot } whose helium cores correspond to helium stars of 6 and 8 M _ { \odot } , respectively .
While the 25 M _ { \odot } stars evolve to the presupernova stages for all combinations of the reaction rates , evolutionary paths of the 20 M _ { \odot } stars proceed significantly different way for some combinations , which are unacceptable for progenitors of supernovae .
Second , we perform calculations of supernova explosions within the limitation of spherical symmetry and compare the calculated abundance ratios with the solar system abundances .
We can deduce some constraints to the reaction rates .
As the results , a conventional rate is adequate for a triple- \alpha reaction rate and a rather higher value of the reaction rate within the upper limit for the experimental uncertainties is favorable for a ^ { 12 } C ( \alpha, \gamma ) ^ { 16 } O rate .