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Title: Carbon synthesis in steady-state hydrogen and helium burning on accreting neutron stars

Superbursts from accreting neutron stars probe nuclear reactions at extreme densities (ρ ≈ 10{sup 9} g cm{sup –3}) and temperatures (T > 10{sup 9} K). These bursts (∼1000 times more energetic than type I X-ray bursts) are most likely triggered by unstable ignition of carbon in a sea of heavy nuclei made during the rapid proton capture process (rp-process) of regular type I X-ray bursts (where the accumulated hydrogen and helium are burned). An open question is the origin of sufficient amounts of carbon, which is largely destroyed during the rp-process in X-ray bursts. We explore carbon production in steady-state burning via the rp-process, which might occur together with unstable burning in systems showing superbursts. We find that for a wide range of accretion rates and accreted helium mass fractions large amounts of carbon are produced, even for systems that accrete solar composition. This makes stable hydrogen and helium burning a viable source of carbon to trigger superbursts. We also investigate the sensitivity of the results to nuclear reactions. We find that the {sup 14}O(α, p){sup 17}F reaction rate introduces by far the largest uncertainties in the {sup 12}C yield.
Authors:
; ; ;  [1] ;  [2]
  1. National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI 48824 (United States)
  2. Department of Physics, McGill University, Montreal, QC H3A 2T8 (Canada)
Publication Date:
OSTI Identifier:
22365303
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 791; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCRETION DISKS; CAPTURE; CARBON; CARBON 12; DENSITY; ELEMENT ABUNDANCE; FLUORINE 17; HEAVY NUCLEI; HELIUM; HELIUM BURNING; HYDROGEN; MASS; NEUTRON STARS; NEUTRONS; NUCLEOSYNTHESIS; OXYGEN 14; PROTONS; SENSITIVITY; STEADY-STATE CONDITIONS; X RADIATION