S. E. Woosley

University of California, Santa Cruz, Santa Cruz, California, United States

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Publications (406)1809.43 Total impact

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    ABSTRACT: Nucleosynthesis, light curves, explosion energies, and remnant masses are calculated for a grid of supernovae resulting from massive stars with solar metallicity and masses from 9.0 to 120 M. The full evolution is followed using an adaptive reaction network of up to 2000 nuclei. A novel aspect of the survey is the use of a one-dimensional neutrino transport model for the explosion. This explosion model has been calibrated to give the observed energy for SN 1987A, using several standard progenitors, and for the Crab supernova using a 9.6 M progenitor. As a result of using a calibrated central engine, the final kinetic energy of the supernova is variable and sensitive to the structure of the presupernova star. Many progenitors with extended core structures do not explode, but become black holes, and the masses of exploding stars do not form a simply connected set. The resulting nucleosynthesis agrees reasonably well with the sun provided that a reasonable contribution from Type Ia supernovae is also allowed, but with a deficiency of light s-process isotopes. The resulting neutron star IMF has a mean gravitational mass near 1.4 M. The average black hole mass is about 9 M if only the helium core implodes, and 14 M , if the entire presupernova star collapses. Only ∼10% of supernovae come from stars over 20 M and some of these are Type Ib or Ic. Some useful systematics of Type IIp light curves are explored.
    Full-text · Article · Nov 2015 · The Astrophysical Journal
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    ABSTRACT: Neutrons produced by the carbon fusion reaction 12C(12C,n)23Mg play an important role in stellar nucleosynthesis. However, past studies have shown large discrepancies between experimental data and theory, leading to an uncertain cross section extrapolation at astrophysical energies. We present the first direct measurement that extends deep into the astrophysical energy range along with a new and improved extrapolation technique based on experimental data from the mirror reaction 12C(12C,p)23Na. The new reaction rate has been determined with a well-defined uncertainty that exceeds the precision required by astrophysics models. Using our constrained rate, we find that 12C(12C,n)23Mg is crucial to the production of Na and Al in Pop-III Pair Instability Supernovae. It also plays a non-negligible role in the production of weak s-process elements as well as in the production of the important galactic gamma-ray emitter 60Fe.
    Full-text · Article · Jul 2015
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    ABSTRACT: Neutrons produced by the carbon fusion reaction ^{12}C(^{12}C,n)^{23}Mg play an important role in stellar nucleosynthesis. However, past studies have shown large discrepancies between experimental data and theory, leading to an uncertain cross section extrapolation at astrophysical energies. We present the first direct measurement that extends deep into the astrophysical energy range along with a new and improved extrapolation technique based on experimental data from the mirror reaction ^{12}C(^{12}C,p)^{23}Na. The new reaction rate has been determined with a well-defined uncertainty that exceeds the precision required by astrophysics models. Using our constrained rate, we find that ^{12}C(^{12}C,n)^{23}Mg is crucial to the production of Na and Al in pop-III pair instability supernovae. It also plays a nonnegligible role in the production of weak s-process elements, as well as in the production of the important galactic γ-ray emitter ^{60}Fe.
    No preview · Article · Jun 2015 · Physical Review Letters
  • S. E. Woosley · Alexander Heger

    No preview · Article · Jun 2015 · The Astrophysical Journal
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    S. E. Woosley · Alexander Heger
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    ABSTRACT: The post-helium burning evolution of stars from 7 to 11 solar masses is complicated by the lingering effects of degeneracy and off-center ignition. Here stars in this mass range are studied using a standard set of stellar physics. Two important aspects of the study are the direct coupling of a reaction network of roughly 220 nuclei to the structure calculation at all stages and the use of a sub grid model to describe the convective bounded flame that develops during neon and oxygen burning. Below 9.0 solar masses, degenerate oxygen-neon cores form that may become either white dwarfs or electron-capture supernovae. Above 10.3 solar masses the evolution proceeds "normally" to iron-core collapse, without composition inversions or degenerate flashes. Emphasis here is upon the stars in between which typically ignite oxygen burning off center. After oxygen burns in a convectively bounded flame, silicon burning ignites in a degenerate flash that commences closer to the stellar center and with increasing violence for stars of larger mass. In some cases the silicon flash is so violent that it could lead to the early ejection of the hydrogen envelope. This might have interesting observable consequences. For example, the death of a 10.0 solar mass star could produce two supernova-like displays, a faint low energy event due to the silicon flash, and an unusually bright supernova many months later as the low energy ejecta from core collapse collides with the previously ejected envelope. The potential relation to the Crab supernova is discussed.
    Preview · Article · May 2015 · The Astrophysical Journal
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    T. Ertl · H. -Th. Janka · S. E. Woosley · T. Sukhbold · M. Ugliano
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    ABSTRACT: Thus far, judging the fate of a massive star (either a neutron star (NS) or a black hole) solely by its structure prior to core collapse has been ambiguous. Our work and previous attempts find a non-monotonic variation of successful and failed supernovae with zero-age main-sequence mass, for which no single structural parameter can serve as a good predictive measure. However, we identify two parameters computed from the pre-collapse structure of the progenitor, which in combination allow for a clear separation of exploding and non-exploding cases with only few exceptions (~1--2.5%) in our set of 621 investigated stellar models. One parameter is M4, defining the enclosed mass for a dimensionless entropy per nucleon of s = 4, and the other is mu4 = dm/dr|_{s=4}, being the mass-derivative at this location. The two parameters mu4 and M4*mu4 can be directly linked to the mass-infall rate, Mdot, of the collapsing star and the electron-type neutrino luminosity of the accreting proto-NS, L_nue ~ M_ns*Mdot, which play a crucial role in the "critical luminosity" concept for the theoretical description of neutrino-driven explosions as runaway phenomenon of the stalled accretion shock. All models were evolved employing the approach of Ugliano et al. for simulating neutrino-driven explosions in spherical symmetry. The neutrino emission of the accretion layer is approximated by a gray transport solver, while the uncertain neutrino emission of the 1.1 Msun proto-NS core is parametrized by an analytic model. The free parameters connected to the core-boundary prescription are calibrated to reproduce the observables of Supernova 1987A for five different progenitor models.
    Preview · Article · Mar 2015
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    ABSTRACT: This is a White Paper in support of the mission concept of the Large Observatory for X-ray Timing (LOFT), proposed as a medium-sized ESA mission. We discuss the potential of LOFT for the study of thermonuclear X-ray bursts on accreting neutron stars. For a summary, we refer to the paper.
    Full-text · Article · Jan 2015
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    S. E. Woosley · Alexander Heger
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    ABSTRACT: The theory underlying the evolution and death of stars heavier than 10 Msun on the main sequence is reviewed with an emphasis upon stars much heavier than 30 Msun. These are stars that, in the absence of substantial mass loss, are expected to either produce black holes when they die, or, for helium cores heavier than about 35 Msun, encounter the pair instability. A wide variety of outcomes is possible depending upon the initial composition of the star, its rotation rate, and the physics used to model its evolution. These heavier stars can produce some of the brightest supernovae in the universe, but also some of the faintest. They can make gamma-ray bursts or collapse without a whimper. Their nucleosynthesis can range from just CNO to a broad range of elements up to the iron group. Though rare nowadays, they probably played a disproportionate role in shaping the evolution of the universe following the formation of its first stars.
    Preview · Article · Jun 2014
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    P. A. Mazzali · A. MacFadyen · S. E. Woosley · E. Pian · M. Tanaka
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    ABSTRACT: The kinetic energy of supernovae (SNe) accompanied by gamma-ray bursts (GRBs) tends to cluster near E52 erg, with 2.E52 erg an upper limit to which no compelling exceptions are found (assuming a certain degree of asphericity), and it is always significantly larger than the intrinsic energy of the GRB themselves (corrected for jet collimation). This energy is strikingly similar to the maximum rotational energy of a neutron star rotating with period 1 ms. It is therefore proposed that all GRBs associated with luminous SNe are produced by magnetars. GRBs that result from black hole formation (collapsars) may not produce luminous SNe. X-ray Flashes (XRFs), which are associated with less energetic SNe, are produced by neutron stars with weaker magnetic field or lower spin.
    Preview · Article · Jun 2014 · Monthly Notices of the Royal Astronomical Society
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    ABSTRACT: Population III supernovae have been the focus of growing attention because of their potential to directly probe the properties of the first stars, particularly the most energetic events that can be seen at the edge of the observable universe. But until now pulsational pair-instability supernovae, in which explosive thermonuclear burning in massive stars fails to unbind them but can eject their outer layers into space, have been overlooked as cosmic beacons at the earliest redshifts. These shells can later collide and, like Type IIn supernovae, produce superluminous events in the UV at high redshifts that could be detected in the near infrared today. We present numerical simulations of a 110 M ☉ pulsational pair-instability explosion done with the Los Alamos radiation hydrodynamics code Radiation Adaptive Grid Eulerian. We find that collisions between consecutive pulsations are visible in the near infrared out to z ~ 15-20 and can probe the earliest stellar populations at cosmic dawn.
    Preview · Article · Nov 2013 · The Astrophysical Journal
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    ABSTRACT: This document presents the results from the Distances subgroup of the Cosmic Frontier Community Planning Study (Snowmass 2013). We summarize the current state of the field as well as future prospects and challenges. In addition to the established probes using Type IA supernovae and baryon acoustic oscillations, we also consider prospective methods based on clusters, active galactic nuclei, gravitational wave sirens and strong lensing time delays.
    Full-text · Article · Sep 2013 · Astroparticle Physics
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    ABSTRACT: We present high-resolution, full-star simulations of the post-ignition phase of Type Ia supernovae using the compressible hydrodynamics code Castro. Initial conditions, including the turbulent velocity field and ignition site, are imported directly from a simulation of the last few hours of presupernova convection using a low Mach number code, Maestro. Adaptive mesh refinement allows the initial burning front to be modeled with an effective resolution of 36,864^3 zones (~136 m/zone). The initial rise and expansion of the deflagration front are tracked until burning reaches the star's edge and the role of the background turbulence on the flame is investigated. The effect of artificially moving the ignition location closer to the star's center is explored. The degree to which turbulence affects the burning front decreases with increasing ignition radius since the buoyancy force is stronger at larger radii. Even central ignition --- in the presence of a background convective flow field --- is rapidly carried off-center as the flame is carried by the flow field. We compare our results to analytic models for burning thermals, and find that they reproduce the general trends of the bubble's size and mass, but underpredict the amount of buoyant acceleration due to simplifying assumptions of the bubble's properties. Overall, we find that the amount of mass that burns prior to flame break out is small, consistent with a "gravitationally confined detonation" occurring at a later epoch, but additional burning will occur following breakout that may modify this conclusion.
    Full-text · Article · Sep 2013 · The Astrophysical Journal
  • C. Gilet · A. S. Almgren · J. B. Bell · A. Nonaka · S. E. Woosley · M. Zingale
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    ABSTRACT: This work presents three-dimensional simulations of core convection in a 15 M ☉ star halfway through its main sequence lifetime. To perform the necessary long-time calculations, we use the low Mach number code MAESTRO, with initial conditions taken from a one-dimensional stellar model. We first identify several key factors that the one-dimensional initial model must satisfy to ensure efficient simulation of the convection process. We then use the three-dimensional simulations to examine the effects of two common modeling choices on the resulting convective flow: using a fixed composition approximation and using a reduced domain size. We find that using a fixed composition model actually increases the computational cost relative to using the full multi-species model because the fixed composition system takes longer to reach convection that is in a quasi-static state. Using a reduced (octant rather than full sphere) simulation domain yields flow with statistical properties that are within a factor of two of the full sphere simulation values. Both the octant and full sphere simulations show similar mixing across the convection zone boundary that is consistent with the turbulent entrainment model. However, the global character of the flow is distinctly different in the octant simulation, showing more rapid changes in the large-scale structure of the flow and thus a more isotropic flow on average.
    No preview · Article · Aug 2013 · The Astrophysical Journal
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    H. Ma · S. E. Woosley · C. M. Malone · A. Almgren · J. B. Bell
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    ABSTRACT: A leading model for Type Ia supernovae (SNe Ia) begins with a white dwarf near the Chandrasekhar mass that ignites a degenerate thermonuclear runaway close to its center and explodes. In a series of papers, we shall explore the consequences of ignition at several locations within such dwarfs. Here we assume central ignition, which has been explored before, but is worth revisiting, if only to validate those previous studies and to further elucidate the relevant physics for future work. A perturbed sphere of hot iron ash with a radius of ~100 km is initialized at the middle of the star. The subsequent explosion is followed in several simulations using a thickened flame model in which the flame speed is either fixed—within the range expected from turbulent combustion—or based on the local turbulent intensity. Global results, including the explosion energy and bulk nucleosynthesis (e.g., 56Ni of 0.48-0.56 M ☉) turn out to be insensitive to this speed. In all completed runs, the energy released by the nuclear burning is adequate to unbind the star, but not enough to give the energy and brightness of typical SNe Ia. As found previously, the chemical stratification observed in typical events is not reproduced. These models produce a large amount of unburned carbon and oxygen in central low velocity regions, which is inconsistent with spectroscopic observations, and the intermediate mass elements and iron group elements are strongly mixed during the explosion.
    Full-text · Article · May 2013 · The Astrophysical Journal
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    Justin M. Brown · S. E. Woosley
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    ABSTRACT: We explore the sensitivity of nucleosynthesis in massive stars to the truncation of supernova explosions above a certain mass. It is assumed that stars of all masses contribute to nucleosynthesis by their pre-explosive winds, but above a certain limiting main sequence mass, M BH, the presupernova star becomes a black hole and ejects nothing more. The solar abundances from oxygen to atomic mass 90 are fit quite well assuming no cutoff at all, i.e., by assuming all stars up to 120 M ☉ make successful supernovae. Little degradation in the fit occurs if M BH is reduced to 25 M ☉. If this limit is reduced further however, the nucleosynthesis of the s-process declines precipitously and the production of species made in the winds, e.g., carbon, becomes unacceptably large compared with elements made in the explosion, e.g., silicon and oxygen. By varying uncertain physics, especially the mass loss rate for massive stars and the rate for the 22Ne(α, n)25Mg reaction rate, acceptable nucleosynthesis might still be achieved with a cutoff as low as 18 M ☉. This would require, however, a supernova frequency three times greater than the fiducial value obtained when all stars explode in order to produce the required 16O. The effects of varying M BH on the nucleosynthesis of 60Fe and 26Al, the production of helium as measured by ΔY/ΔZ, and the average masses of compact remnants are also examined.
    Full-text · Article · Feb 2013 · The Astrophysical Journal
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    ABSTRACT: A diversity of models of SNIa have been presented in the literature, but all agree --- in one form or another --- that the event involves a thermonuclear explosion on or in the vicinity of a C/O white dwarf. Whether this explosion occurs as a deflagration, detonation, or both is somewhat of an open question, but all models ultimately must obtain the proper nucleosynthetic yields to reproduce the observed lightcurve and spectra. I describe some of the efforts of our group over the last few years involving the single degenerate, Chandrasekhar model. In particular, I describe our low Mach number MAESTRO simulations of the core convection and simmering that leads up to an off-center ignition. I also discuss how we have mapped these low Mach number results into our compressible hydrodynamics code, CASTRO, with a thickened flame model to evolve the ignition spot as it buoyantly rises toward the stellar surface. Upon breaking through the surface, the deflagration may transition to a detonation in regions of large shear or compression. The resulting explosion can then be put into a radiation hydrodynamic/transfer code to obtain synthetic spectra.
    Full-text · Article · Jan 2013
  • Tuguldur Sukhbold · S. E. Woosley · B. Paxton · A. Heger
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    ABSTRACT: The compactness of the core of a pre-supernova star is one of the important unexplored issues in progenitor evolution. Recent studies have found the core compactness to be varying non-monotonically as a function of ZAMS mass. In this work we have calculated a large grid of 1D full stellar and naked C/O core models using the implicit hydrodynamic code KEPLER and the open source stellar evolution code MESA, in order to gain a better insight in core compactness' dependence on the stellar mass and convection physics. We find the complicated evolution during C burning acts as the main cause of the non-monotonic variation of compactness, and the whole compactness curve as a function of mass to be quite dependent on the treatment of semiconvection. We also conclude that the C/O core mass is the main discriminant of pre-supernova structure.
    No preview · Article · Jan 2013
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    ABSTRACT: The first stars are the key to the formation of primitive galaxies, early cosmological reionization and chemical enrichment, and the origin of supermassive black holes. Unfortunately, in spite of their extreme luminosities, individual Population III stars will likely remain beyond the reach of direct observation for decades to come. However, their properties could be revealed by their supernova explosions, which may soon be detected by a new generation of NIR observatories such as JWST and WFIRST. We present light curves and spectra for Pop III pair-instability supernovae calculated with the Los Alamos radiation hydrodynamics code RAGE. Our numerical simulations account for the interaction of the blast with realistic circumstellar envelopes, the opacity of the envelope, and Lyman absorption by the neutral IGM at high redshift, all of which are crucial to computing the NIR signatures of the first cosmic explosions. We find that JWST will detect pair-instability supernovae out to z > 30, WFIRST will detect them in all-sky surveys out to z ~ 15 - 20 and LSST and Pan-STARRS will find them at z ~ 7 - 8. The discovery of these ancient explosions will probe the first stellar populations and reveal the existence of primitive galaxies that might not otherwise have been detected.
    Full-text · Article · Nov 2012 · The Astrophysical Journal
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    ABSTRACT: The first stars ended the cosmic Dark Ages and created the first heavy elements necessary for the formation of planets and life. The properties of these stars remain uncertain, and it may be decades before individual Pop III stars are directly observed. Their masses, however, can be inferred from their supernova explosions, which may soon be found in both deep-field surveys by JWST and in all-sky surveys by WFIRST. We have performed radiation hydrodynamical simulations of the near infrared signals of Pop III pair-instability supernovae in realistic circumstellar environments with Lyman absorption by the neutral intergalactic medium. We find that JWST and WFIRST will detect these explosions out to z ~ 30 and 20, respectively, unveiling the first generation of stars in the universe.
    Preview · Article · Sep 2012 · The Astrophysical Journal Letters
  • A. Heger · S. Woosley · P. Vo · K. Chen · C. Joggerst
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    ABSTRACT: The first generation of stars in the universe may have been different from stars in the present-day universe. They may have been typically more massive than stars that form today, or may have rotated faster and hence their evolution, explosion, and overall nucleosynthesis yield could have been quite different. Theoretical models are needed to qualify and quantify these differences. Here we present nucleosynthesis results from the first generations of stars in the universe and how they may be connected to observed abundance patterns from ultra-metal poor stars.
    No preview · Article · Aug 2012

Publication Stats

26k Citations
1,809.43 Total Impact Points


  • 1970-2015
    • University of California, Santa Cruz
      • Department of Astronomy and Astrophysics
      Santa Cruz, California, United States
  • 2003-2012
    • University of Chicago
      Chicago, Illinois, United States
  • 1994-2010
    • University of California Observatories
      Santa Cruz, California, United States
  • 2008
    • University of Washington Seattle
      • Institute for Nuclear Theory
      Seattle, WA, United States
  • 2006
    • Space Telescope Science Institute
      Baltimore, Maryland, United States
  • 1980-2006
    • Lawrence Livermore National Laboratory
      • Physics Division
      Livermore, California, United States
  • 2005
    • Ecole normale supérieure de Lyon
      Lyons, Rhône-Alpes, France
  • 1998
    • Max Planck Institute for Astrophysics
      Arching, Bavaria, Germany
  • 1993
    • Clemson University
      • Department of Physics and Astronomy
      Anderson, IN, United States
    • The University of Arizona
      • Department of Astronomy
      Tucson, Arizona, United States
  • 1987
    • University of Toronto
      Toronto, Ontario, Canada
  • 1986
    • University of California, Berkeley
      • Department of Physics
      Berkeley, California, United States
    • Northwestern University
      • Department of Physics and Astronomy
      Evanston, Illinois, United States
  • 1975-1979
    • California Institute of Technology
      Pasadena, California, United States
  • 1974
    • University of Texas at Austin
      Austin, Texas, United States