Energy rates due to weak decay rates of vanadium isotopes in stellar environment

Abstract

The neutrino cooling and gamma heating rates are considered as an important input needed to study the final phases of the evolution of high-mass stars. The weak-interaction mediated processes, namely the $\beta$-decay and electron capture, significantly change the lepton to baryon ratio and accelerate the contraction of the core. The emission of resulting neutrinos/antineutrinos tend to cool the stellar core. On the other hand gamma rays are produced because of electron capture and $\beta$-decay to excited states in daughter nuclei. These gamma rays heat the core and contribute to increase of entropy which may cause convection to occur. In the present work, the weak-interaction heating and cooling rates on a chain of twenty two isotopes of vanadium having mass in the range 43–64 have been estimated using the proton-neutron quasiparticle random phase approximation theory. The rates have been computed for the temperature ranging from ($10^{7}\mbox{--}3\times 10^{10}$) K and for the density range $(10\mbox{--}10^{11})~\mbox{g/cm}^{3}$. Our calculated neutrino energy loss rates have also been compared with the previously reported rates calculated using other theoretical models. At high stellar temperatures, our rates are larger by 1–2 orders of magnitude as compared to previous results.