Effective Stellar $\beta$-Decay Rates of Nuclei with Long-lived Isomers: ${}^{26}$Al and ${}^{34}$Cl

Abstract

Isotopes with low-lying long-lived isomers can behave very differently from other isotopes in astrophysical environments. In particular, the assumption of thermal equilibrium in computing the temperature-dependent $\beta$-decay rates of such isotopes can fail below certain temperatures. We focus on the $\beta$-decay of ${}^{26}$Al since it is one of the most important isotopes in observational astrophysics and has a low-lying isomeric state; we compare and contrast these results with ${}^{34}$Cl. We rule out recently reported ${}^{26}$Al effective $\beta$-decay rates that showed large differences from previous calculations, finding that we agree with the earlier results. We conclude that in general, effective $\beta$-decay rates should be defined separately for the ground and isomeric states at temperatures where thermal equilibrium cannot be achieved.

arXiv comment9 pages, 7 figures

References in corpus (5)

• The nucleosynthesis of Al26 and Fe60 in solar metallicity stars extending in mass from 11 to 120 Msun: the hydrostatic and explosive contributions
• The Effects of Thermonuclear Reaction-Rate Variations on 26Al Production in Massive Stars: a Sensitivity Study
• Lifetimes of 26Al and 34Cl in an astrophysical plasma
• Treatment of isomers in nucleosynthesis codes
• Neutrino Spectra from Nuclear Weak Interactions in $sd$-Shell Nuclei Under Astrophysical Conditions

Cited by in corpus (8)

• Atlas of Nuclear Isomers -- Second Edition
• Astromers: Nuclear Isomers in Astrophysics
• Astromers in the radioactive decay of r-process nuclei
• Aluminium-26 from massive binary stars I: non-rotating models
• Urca Cooling in Neutron Star Crusts and Oceans: Effects of Nuclear Excitations
• How Do Nuclear Isomers Influence the Gamma-Ray Bursts in Binary Neutron Star Mergers?
• The Impact of the New ${}^{59}$Fe Decay Rates on ${}^{60}$Fe and ${}^{26}$Al Nucleosynthesis in Massive Stars
• Sensitivity of Neutron-Rich Nuclear Isomer Behavior to Uncertainties in Direct Transitions