Re-estimation of 180Ta nucleosynthesis in light of newly constrained reaction rates

Abstract Recent measurements of the nuclear level densities and γ -ray strength functions below the neutron thresholds in 180,181,182 Ta are used as input in the nuclear reaction code TALYS. These experimental average quantities are utilized in the calculations of the 179,180,181 Ta radiative neutron capture cross sections. From the latter, astrophysical Maxwellian-averaged ( n , γ ) cross sections (MACS) and reaction rates are extracted, which in turn are used in large astrophysical network calculations to probe the production mechanism of 180 Ta. These calculations are performed for two scenarios, the s -process production of 180,181 Ta in Asymptotic Giant Branch (AGB) stars and the p -process nucleosynthesis of Ta m 180 in Type-II supernovae. Based on the results from this work, the s -process in stellar evolution is considered negligible in the production of Ta m 180 whereas 181 Ta is partially produced by AGB stars. The new measurements strongly constrain the production and destruction rates of Ta m 180 at p -process temperatures and confirm significant production of nature's rarest stable isotope Ta m 180 by the p -process.