Effects of a New Triple-α Reaction on the s-Process in Massive Stars

Effects of a new triple-alpha reaction rate on the s-process during the evolution of a massive star of 25 M-circle dot are investigated for the first time. Although the s-process in massive stars has been believed to be established with only minor change, we find that the s-process with use of the new rate during the core He-burning is very inefficient compared to the case with the previous triple-alpha rate. However, the difference of the overproduction is found to be largely compensated by the subsequent C-burning. Since the s-process in massive stars has been attributed so far to the neutron irradiation during core He-burning, our finding reveals the importance of C-burning for the s-process during the evolution of massive stars. Since the overproduction level is not different as a whole for the two distinctly different rates, the weak s-process in massive stars does not testify the validity of the new rate.