Final Products of the rp-Process on Accreting Neutron Stars

Using both shell-flash and realistic models on accreting neutron stars with the full nuclear reaction network up to Bi, we investigate the detailed relation between the final products of the rp-process and the ignition pressure. We find that nuclear fuels of H and super(4)He are almost burned out after the flash and that the mass number of synthesized nuclei reaches to ~100 in the pressure range from 10 super(23) to 10 super(23.5) dyn cm super(-2) for a neutron star of 1.4 M sub(o) and 10 km radius. Furthermore, p-nuclei up to super(126)Xe are found to be produced after the flash, thanks to our large network. The postprocess nucleosynthesis for accretion rates of 3 x 10 super(-10), 3 x 10 super(-9), and 10 super(-8) M sub(o) yr super(-1), which corresponds to an ignition pressure from 10 super(22.7) to 10 super(22.9) dyn cm super(-2), reveals that H is exhausted completely during the burst. This is because H decreases significantly as a result of the steady burning before the burst and convective mixing at the initial stage; we find that super(64)Zn is the most abundant element after the burst.