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 ⁴He are almost burned out after the flash and that the mass number of synthesized nuclei reaches to ≃100 in the pressure range from 10²³ to 10^23.5 dyn cm ^-2 for a neutron star of 1.4 M_⊙ and 10 km radius. Furthermore, p-nuclei up to ¹²⁶Xe are found to be produced after the flash, thanks to our large network. The postprocess nucleosynthesis for accretion rates of 3 × 10^-10, 3 × 10^-9, and 10^-8 M_⊙ yr^-1, which corresponds to an ignition pressure from 10^22.7 to 10^22.9 dyn cm ^-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 ⁶⁴Zn is the most abundant element after the burst.