Stellar ${\beta }^{-}$-decay rate of ${}^{63}$Ni and its impact on the $s$-process nucleosynthesis in massive stars

Abstract

The ${\beta }^{-}$-decay rate of ${}^{63}$Ni, an important branching point, affects the subsequent nucleosynthesis in the weak component of the slow-neutron capture process (weak $s$-process). To evaluate the impact of the uncertainties of stellar lifetime of ${}^{63}$Ni on abundances, we calculate the contribution to ${\beta }^{-}$-decay rates from its excited states using the large-scale shell model with various interactions and also explore the atomic effects in the highly ionized plasma. In the core He burning stage and the shell C burning stage of massive stars, our new rates can be larger than those from Takahashi and Yokoi(1987) by up to a factor of 4 and 6, respectively. We evaluate the impact of the stellar decay rates of ${}^{63}$Ni on the nucleosynthesis of $A=60\sim 90$ in a star with an initial mass of 25 $M_{⨀}$ and solar metalicity. We find that the new rates can lead to the abundance changes of ${}^{64}$Ni, ${}^{63}$Cu, ${}^{65}$Cu, ${}^{64}$Zn, ${}^{66}$Zn, ${}^{67}$Zn, and ${}^{68}$Zn by up to $18\%$, $14\%$, $7\%$, $98\%$, $16\%$, $15\%$, and $13\%$, respectively, after the shell C burning stage at the Lagrangian mass coordinate $M_r=2M_{⨀}$. The enhancement of the decay rate of ${}^{63}$Ni increases the weak $s$-process efficiency of nuclei after ${}^{65}$Cu.

References in corpus (13)

• Modules for Experiments in Stellar Astrophysics (MESA)
• Modification of the Brink-Axel Hypothesis for High Temperature Nuclear Weak Interactions
• Deep underground laboratory measurement of ${}^{13}$C($\alpha$,$n$)${}^{16}$O in the Gamow windows of the $s$- and $i$-processes
• ${}^{62}$Ni($n,\gamma$) and ${}^{63}$Ni($n,\gamma$) cross sections measured at n_TOF/CERN
• The stellar beta-decay rate of 134Cs and its impact on the Barium nucleosynthesis in the s process
• Measurement of the ${}^{70}$Ge($n,\gamma$) cross section up to 300~keV at the CERN n_TOF facility
• Measurement of the ${}^{154}$Gd(n,$\gamma$) cross section and its astrophysical implications
• Measurement of 73Ge(n,g) cross sections and implications for stellar nucleosynthesis
• The ${}^{59}$Fe(n, γ)${}^{60}$Fe Cross Section from the Surrogate Ratio Method and Its Effect on the ${}^{60}$Fe Nucleosynthesis
• The 95zr(n, gamma)96zr cross section from the surrogate ratio method and its effect on the s-process nucleosynthesis
• Stellar ($n,\gamma$) cross section of ${}^{23}$Na
• Thermonuclear 17O(n,gamma)18O reaction rate and its astrophysical implications
• Allowed ${\beta }^{-}$ decay of bare atoms with A$\sim$ 60-80 in stellar environments