Explosive nucleosynthesis in magnetohydrodynamical jets from collapsars

We investigate the nucleosynthesis of a massive star whose mass in the main sequence stage is M_ms = 70 M_⊙ that corresponds to the helium core or helium star of M_α = 32 M⊙. Numerical calculations of the nucleosynthesis are performed during the stage of hydrostatic stellar evolution until the core composed of iron-group nuclei (Fe core) begins to collapse. A collapsar model whose jets are driven by two-dimensional magnetohydrodynamical effects of a differentially rotating core is constructed. The explosive nucleosynthesis inside the jets of a specified collapsar model is followed along the trajectories of stream lines. We combine the results of both detailed hydrostatic and explosive nucleosyntheses to compare the solar system abundances. We show that the agreement is considerably improved compared with the case without the detailed hydrostatic nucleosynthesis included. We suggest that many radioactive nuclei such as ⁴⁴Ti and ^56,57Ni are produced if the jets continue for more than 10 s, which would become crucial for the observation of abundance distribution in young supernova remnants.