Models for Type I X-Ray Bursts with Improved Nuclear Physics

By Stan Woosley, Alexander Heger, A. Cumming, R. Hoffman, J. Pruet, T. Rauscher, J. Fisker, Hendrik Schatz, B. A. Brown, Michael Wiescher. 2003

289 citations recorded by the source corpus.

Multizone models of Type I X-ray bursts are presented that use an adaptive nuclear reaction network of unprecedented size, up to 1300 isotopes, for energy generation and include the most recent measurements and estimates of critical nuclear physics. Convection and radiation transport are included in calculations that carefully follow the changing composition in the accreted layer, both during the bursts themselves and in their ashes. Sequences of bursts, up to 15 in one case, are followed for two choices of accretion rate and metallicity, up to the point at which a limit cycle equilibrium is established. For = 1.75 × 10-9 M⊙ yr-1 (and = 3.5 × 10-10 M⊙ yr-1, for low metallicity), combined hydrogen-helium flashes occur. These bursts have light curves with slow rise times (seconds) and long tails. The rise times, shapes, and tails of these light curves are sensitive to the efficiency of nuclear burning at various waiting points along the rp-process path, and these sensitivities are explored. Each displays "compositional inertia" in that its properties are sensitive to the fact that accretion occurs onto the ashes of previous bursts that contain leftover hydrogen, helium, and CNO nuclei. This acts to reduce the sensitivity of burst properties to metallicity. Only the first anomalous burst in one model produces nuclei as heavy as A = 100. For the present choice of nuclear physics and accretion rates, other bursts and models make chiefly nuclei with A ≈ 64. The amount of carbon remaining after hydrogen-helium bursts is typically ≲1% by mass and decreases further as the ashes are periodically heated by subsequent bursts. For = 3.5 × 10-10 M⊙ yr-1 and solar metallicity, bursts are ignited in a hydrogen-free helium layer. At the base of this layer, up to 90% of the helium has already burned to carbon prior to the unstable ignition of the helium shell. These helium-ignited bursts have (1) briefer, brighter light curves with shorter tails, (2) very rapid rise times (<0.1 s), and (3) ashes lighter than the iron group.

Subfields: Astronomy and Astrophysics, Geophysics

View Paper: https://www.semanticscholar.org/paper/8acff971cb7c92c8928498c6eb6feee357694925

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Citations in the corpus

The rp-Process in Neutrino-driven Winds (2006, background): “To date the thermonuclear explosions of hydrogen-rich material on accreting neutron stars (X-ray bursts) have been considered to be the promising astrophysical site associated to the occurrence of rpprocess (e.g., Schatz et al. 1998; Koike et al. 1999; Brown et al. 2002; Woosley et al. 2004).”
MODULES FOR EXPERIMENTS IN STELLAR ASTROPHYSICS (MESA): BINARIES, PULSATIONS, AND EXPLOSIONS (2015, background): “The luminosity at the base of the envelope is set to L = 1.6×1034 ergs s−1 (Woosley et al. 2004).”
THE JINA REACLIB DATABASE: ITS RECENT UPDATES AND IMPACT ON TYPE-I X-RAY BURSTS (2010, methodology): “The one-dimensional, multi-zone hydrodynamics code Kepler (Woosley et al. 2004) was used to simulate Type-I X-ray bursts using the latest snapshot version of the REACLIB database (REACLIB V1.”
Thermonuclear Burst Oscillations (2012, background): “One-dimensional simulations show that radiative heat transport should be important in all bursts, with convection also playing an important role (Woosley et al. 2004; Weinberg, Bildsten & Schatz 2006).”
Six new candidate ultracompact X-ray binaries (2007, background): “The long mixed hydrogen/helium flashes do not last longer than a few hundred seconds and may have irregularly shaped decay phases due to the various waiting points in the rpprocess reaction chain (e.g., Schatz et al. 2001; Woosley et al. 2004).”
THE EQUATION OF STATE FROM OBSERVED MASSES AND RADII OF NEUTRON STARS (2010, background): “The convective zone is expected to reach the photosphere during a powerful burst(Woosley et al. 2004; Weinberg et al. 2005) thereby polluting the accreted material with heavier nuclei synthesized during the burst.”
CONVECTIVE–REACTIVE PROTON–12C COMBUSTION IN SAKURAI'S OBJECT (V4334 SAGITTARII) AND IMPLICATIONS FOR THE EVOLUTION AND YIELDS FROM THE FIRST GENERATIONS OF STARS (2010, background): “These combustion events are encountered as well in X-ray burst calculations of accreting neutron stars (Woosley et al. 2004; Piro & Bildsten 2007), and accreting white dwarfs (Cassisi et al. 1998) that may be the progenitors of SN Ia. Convective-reactive events have been found in post-RGB stellar…”
Long Type I X-Ray Bursts and Neutron Star Interior Physics (2005, background): “Although approximate, this ignition criterion agrees well with more detailed linear stability (Narayan & Heyl 2003) and time-dependent calculations (Woosley et al. 2004) for H/He burning, and we expect it to be accurate here also (Cooper & Narayan 2005).”
THE REMARKABLE DEATHS OF 9–11 SOLAR MASS STARS (2015, methodology): “An important aspect of the calculation was the use of a moderate-sized nuclear reaction network directly coupled to the stellar structure (for prior examples, see Woosley et al. 2004; Jones et al. 2013).”