Abstract
We investigate the r-process nucleosynthesis during the magnetohydrodynamical (MHD) explosion of a supernova in a helium star of 3.3 M⊙, where effects of neutrinos are taken into account using the leakage scheme in the two-dimensional (2D) hydrodynamic code. Jet-like explosion due to the combined effects of differential rotation and magnetic field is able to erode the lower electron fraction matter from the inner layers. We find that the ejected material of low electron fraction responsible for the r-process comes out from just outside the neutrino sphere deep inside the Fe-core. It is found that heavy element nucleosynthesis depends on the initial conditions of rotational and magnetic fields. In particular, the third peak of the distribution is significantly overproduced relative to the solar system abundances, which would indicate a possible r-process site owing to MHD jets in supernovae.
Highlights
Study of the r-process has been developed considerably keeping pace with the terrestrial experiments of nuclear physics far from the stability line of nuclides [1]
Among the three peaks, which correspond to the elements of 80Se, 130Te, and 195Pt, in the abundance pattern for the solar system r-elements, the transition from the second to third peak elements has been stressed by nuclear physicists [2]
Supernovae could be one of the astrophysical sites of the r-process [2, 3], explosion mechanism is not still completely resolved, where supernova explosions are originated from the gravitational collapse of massive stars of M ≥ 8 M⊙ [4, 5]
Summary
Study of the r-process has been developed considerably keeping pace with the terrestrial experiments of nuclear physics far from the stability line of nuclides [1]. The ZEUS-2D code [28] has been modified to include an equation of state [29], electron captures with a simple scheme of neutrino (]-) transport [23] Adopting these achievements, Nishimura et al [30] have performed 2D/MHD calculations to study possibilities of the r-process during the supernova explosion of massive stars under the assumption of adiabatic. Winteler et al [32] have shown the r-process nucleosynthesis with the use of results of a magnetorotationally driven supernova simulation, where they have performed 3D calculations with a 3D spectral scheme for neutrinos They have obtained enough r-elements, their MHD simulation has finished at around 31 ms after the bounce.
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