Metallicity effects in type I X-ray bursts
Hydrodynamic Models of Type I X-Ray Bursts: Metallicity Effects,
by J. Jose, F. Moreno, A. Parikh, and C. Iliadis
The Astrophysical Journal Supplement Series 189 (2010) 204–239
Type I X-ray bursts are driven by charged particle reactions. In the regime for combined H/He-ignition, the main nuclear flow is dominated by rapid proton-captures and β+-decays), the 3α-reaction, and a suite of (α,p) and (p,γ) reactions. The main flow is expected to proceed away from the valley of stability, eventually reaching the proton drip-line beyond A = 38. The paper presents a detailed study of the nucleosynthesis and nuclear processes powering type I X-ray bursts. The reported 11 bursts have been computed by means of a spherically symmetric (1D) Lagrangian hydrodynamic code, linked to a nuclear reaction network that contains 325 isotopes (from 1H to 107Te) and 1392 nuclear processes. These evolutionary sequences, followed from the onset of accretion up to the explosion and expansion stages, have been performed for two different metallicities to explore the dependence between the extension of the main nuclear flow and the initial metal content. Dominant reactions and the products of nucleosynthesis have been analyzed, together with the physical parameters that determine the light curve (including recurrence times, ratios between persistent and burst luminosities, or the extent of the envelope expansion). Results are in qualitative agreement with the observed properties of some well-studied bursting sources.
