Abundances of La-138 and Ta-180 Through nu-Nucleosynthesis in 20M(circle dot) Type II Supernova Progenitor, Guided by Stellar Models for Seeds

作者：Lahkar N^*; Kalita S; Duorah H L; Duorah K

来源：Journal of Astrophysics and Astronomy, 2017, 38(1): 8.

DOI：10.1007/s12036-017-9428-y

• Supernova
• nucleosynthesis
• neutrino process

Yields of nature's rarest isotopes La-138 and Ta-180 are calculated by neutrino processes in the Neshell of density p approximate to 10(4) g/cc in a type II supernova (SN II) progenitor of mass 20M(circle dot). Two extended sets of neutrino temperature -T-nu e = 3, 4, 5, 6 MeV and T-nu(mu/t) = 4, 6, 8, 10, 12 MeV respectively for charged and neutral current processes are taken. Solar mass fractions of the seeds La-139, Ta-181, Ba-138 and Hf-180 are taken for calculation. They are assumed to be produced in some s-processing events of earlier generation massive 'seed stars' with average interior density range
approximate to 10(3) -10(6) g/cc. The abundances of these two elements are calculated relative to O-16 and are found to be sensitive to the neutrino temperature. For neutral current processes with the neutron emission branching ratio, b(n) = 3.81 x 10(-4) and b(n) = 9.61 x 10(-1), the relative abundances of La-138 lie in the ranges 4.48x10(-14) -2.94x10(-13) and 1.13x10-(10) -743x10(-10) respectively. Similarly, the relative abundances of Ta-180 lie in the ranges 1.80 x 10(-15) -1.17 x 10(-14) and 4.53 x 10(-12) -2.96 x 10(-11) respectively for the lower and higher values of the neutron emission branching ratio. For charged current processes, the relative abundances of La-138 and Ta-180 are found to be in the ranges 1.38 x 10(-9) -7.62 x 10(-9) and 2.09 x 10(-11) -1.10 x 10(-10) respectively. Parametrized by density of the 'seed stars', the yields are found to be consistent with recent supernova simulation results throughout the range of neutrino temperatures. La-138 and Ta-180 are found to be efficiently produced in charged current interaction.

• 出版日期2017-3