Nucleosynthesis and remnants in massive stars of solar metallicity

Abstract

Hans Bethe contributed in many ways to our understanding of the supernovae that happen in massive stars, but, to this day, a first principles model of how the explosion is energized is lacking. Nevertheless, a quantitative theory of nucleosynthesis is possible. We present a survey of the nucleosynthesis that occurs in 32 stars of solar metallicity in the mass range 12 to 120 M ⊙ . The most recent set of solar abundances, opacities, mass loss rates, and current estimates of nuclear reaction rates are employed. Restrictions on the mass cut and explosion energy of the supernovae based upon nucleosynthesis, measured neutron star masses, and light curves are discussed and applied. The nucleosynthetic results, when integrated over a Salpeter initial mass function (IMF), agree quite well with what is seen in the sun. We discuss in some detail the production of the long lived radioactivities, 26 Al and 60 Fe, and why recent model-based estimates of the ratio 60 Fe/ 26 Al are overly large compared with what satellites have observed. A major source of the discrepancy is the uncertain nuclear cross sections for the creation and destruction of these unstable isotopes.

Evidence for Magnetar Formation in Broad-lined Type Ic Supernovae1998bw and 2002ap

“…Such a parameter difference for SN 1998bw between the two-component model and the magnetar model may imply a difference for its progenitor. The ejecta mass, 10M , in the two-component model points to a massive single star, while M ej = 2.6M in the magnetar model favors a binary origin (Fremling et al 2016), although a ∼ 4M Wolf-Rayet star (here a remnant magnetar with typical mass 1.4M is assumed) evolved from a single 35M main sequence star is also possible (Woosley & Heger 2007;Woosley 2010).…”

The Development of Explosions in Axisymmetric Ab Initio Core-Collapse Supernova Simulations of 12–25 Stars

“…In these non-NSE regions, we additionally track, but do not react, the abundance of neutrons, protons, and an auxiliary heavy species. The initial abundances of these nonreactive species are built from the composition given for each progenitor by Woosley & Heger (2007) with properties of the auxiliary heavy species chosen to conserve the electron fraction of material that is not in the a-network. When material must advect from an NSE region into a non-NSE region or when the temperature of a zone falls so that NSE is no longer appropriate, the composition of the advected or transitioned material must be determined.…”

Nucleosynthesis in Supernovae, Hypernovae/Gamma-ray Bursts and Compact Binary Mergers

“…Interim approaches beyond piston or thermal bomb models [20,34,53,81] try to mimic multi-D neutrino heating in a spherical approach in order to obtain more appropriate predictions of the explosion energy, mass cut between neutron star and ejecta, as well as nucleosynthesis (including the effects of neutrinos on Y e , the proton/nucleon ratio): Fröhlich et al [15] multiplied neutrino-capture rates by a factor, causing additional ν-heating, to obtain observed explosion energies. Ugliano, Ertl, and Sukhbold et al [68] introduced a tuned, time-dependent central neutrino source that approximately captures the essential effects of (3D) neutrino transport (PHOTB).…”

“…CCSNe contribute to galactic evolution via their wind ejecta, and after explosion via (a) ejecta of essentially unburned matter from the outer stellar zones and (b) explosively processed matter from the inner ejecta. 60 Fe (half-life 2.6 × 10 6 y) is an example for (a) and goes back to hydrostatic burning stages [34,37,81]. Recent findings show that it can witness the last CCSNe near the solar system about 2 to 3 million years ago [30,76].…”