The Stellar β-decay Rate of 134Cs and Its Impact on the Barium Nucleosynthesis in the s-process

We have calculated the stellar beta-decay rate of the important s-process branching point Cs-134 based on the state-of-the-art shell model calculations. At typical s-process temperatures (T similar to 0.2-0.3 GK), our new rate is one order of magnitude lower than the widely used rate from Takahashi and Yokoi (hereafter TY87). The impact on the nucleosynthesis in AGB stars is investigated with various masses and metallicities. Our new decay rate leads to an overall decrease in the Ba-134/Ba-136 ratio, and well explains the measured ratio in meteorites without introducing the i-process. We also derive the elapsed time from the last AGB nucleosynthetic event that polluted the early solar system to be >28 Myr based on the Cs-135/Cs-133 ratio, which is consistent with the elapsed times derived from Pd-107 and Hf-182. The s-process abundance sum of Ba-135 and Cs-135 is found to increase, resulting in a smaller r-process contribution of Ba-135 in the solar system.

Automated summary

The study finds that the new stellar beta-decay rate of Cs-134 is one order of magnitude lower than the previous rate, impacting the nucleosynthesis in AGB stars and explaining the ratios in meteorites without the need for the introduction of the i-process.