Abundances of La138 and Ta180 Through ν-Nucleosynthesis in $20 M_odot$ Type II Supernova Progenitor, Guided by Stellar Models for Seeds

Journal of astrophysics and astronomy

K. Duorah¹  H. L. Duorah¹  S. Kalita¹  N. Lahkar1 2¹ 

[1] Department of Physics, Gauhati University, Guwahati 781 014, India.$$

关键词: Supernova;    nucleosynthesis;    neutrino process;   

DOI  :  

学科分类：天文学(综合)

来源: Indian Academy of Sciences

【 摘 要 】

Yields of nature’s rarest isotopes La^{138} and Ta^{180} are calculated by neutrino processes in the Ne-shell of density $ho ≈ 10^4 g/cc$ in a type II supernova (SN II) progenitor of mass 20 $M_odot$. Two extended sets of neutrino temperature $- T_{ue}$ = 3, 4, 5, 6 MeV and $T_{u(mu/au)}$= 4, 6, 8, 10, 12 MeV respectively for charged and neutral current processes are taken. Solar mass fractions of the seeds La139, Ta181, Ba138 and Hf180 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 $langleρangle approx 10^3−10^6 g/cc$. The abundances of these two elements are calculated relative to O16 and are found to be sensitive to the neutrino temperature. For neutral current processes with the neutron emission branching ratio, $b_n = 3.81 imes 10^{-4}$ and $b_n = 9.61 imes 10^{−1}$, the relative abundances of La138 lie in the ranges $4.48 imes 10^{−14}−2.94 imes 10^{−13}$ and $1.13 imes 10^{−10} − 7.43 imes 10^{−10}$ respectively. Similarly, the relative abundances of Ta180 lie in the ranges $1.80 imes 10^{−15} − 1.17 imes 10^{−14}$ and 4.53 imes 10^{−12}−2.96 × 10^{−11} respectively for the lower and higher values of the neutron emission branching ratio. For charged current processes, the relative abundances of La138 and Ta180 are found to be in the ranges $1.38 imes 10^{−9} − 7.62 imes 10^{−9}$ and $2.09 imes 10^{-11} − 1.10 imes 10^{−10}$ 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. La138 and Ta180 are found to be efficiently produced in charged current interaction.

【 授权许可】

Unknown