New estimate for the time-dependent thermal nucleosynthesis of Ta

Hayakawa, Takehito; Kajino, Toshitaka*; Chiba, Satoshi; Mathews, G. J.*

The nucleosynthesis of Ta has remained an unsolved problem. The supernova neutrino process has been proposed as the origin of Ta but its model calculation overproduces the Ta solar abundance. This may originate from the unique feature that the naturally occurring abundance of Ta is actually a meta-stable isomer, while the ground state is beta-unstable. We have made a new time-dependent calculation of the supernova production ratio of the long-livedisomer in Ta. Such a time-dependent solution is crucial for understanding the production and survival of this isotope. We find that the explicit time evolution of the synthesis of Ta using the available nuclear data shows Ta can be produced by neutrino process and neutrino temperature of 4 MeV.