Effects of a New Triple-{\alpha} Reaction on the S-process in Massive Stars

TL;DR

This study examines how a new triple-alpha reaction rate significantly impacts the s-process nucleosynthesis in a 25 solar mass star, revealing the importance of C-burning in this process.

Contribution

It introduces the first investigation of the effects of a new triple-alpha rate on the s-process in massive stars, highlighting the role of C-burning.

Findings

The new rate makes the s-process during core He-burning very inefficient.

C-burning largely compensates for the reduced s-process during He-burning.

The s-process in massive stars is more influenced by C-burning than previously thought.

Abstract

Effects of a new triple-{\alpha} reaction rate on the s-process during the evolution of a massive star of 25 M\odot 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.