Chemical Yields from Supernovae and Hypernovae

We review the final stages of stellar evolution, supernova properties, and chemical yields as a function of the progenitor’s mass M. (1) 8 - 10 Ms stars are super-AGB stars when the O+Ne+Mg core collapses due to electron capture. These AGB-supernovae may constitute an SN 2008S-like sub-class of Type IIn supernovae. These stars produce little alpha-elements and Fe-peak elements, but are important sources of Zn and light p-nuclei. (2) 10 - 90 Ms stars undergo Fe-core collapse. Nucleosynthesis in aspherical explosions is important, as it can well reproduce the abundance patterns observed in extremely metal-poor stars. (3) 90 - 140 Ms stars undergo pulsational nuclear instabilities at various nuclear burning stages, including O and Si-burning. (4) 140 - 300 Ms stars become pair-instability supernovae, if the mass loss is small enough. (5) Stars more massive than 300 Ms undergo core-collapse to form intermediate mass black holes.

💡 Research Summary

The paper provides a comprehensive review of the final evolutionary stages of massive stars, the characteristics of their supernova (SN) and hypernova (HN) explosions, and the resulting chemical yields as a function of the progenitor’s initial mass (M). The authors divide the mass spectrum into five distinct regimes, each associated with a different collapse mechanism and nucleosynthetic signature.

1. 8–10 M☉ (Super‑AGB / Electron‑capture SNe) – Stars in this range develop O+Ne+Mg cores that become unstable to electron capture. The ensuing electron‑capture supernova (ECSN) is relatively low‑energy, ejects little α‑elements or Fe‑peak nuclei, but is a prolific source of zinc and light p‑process isotopes (e.g., ^92,94Mo). The authors argue that such events may underlie the SN 2008S‑like subclass of Type IIn SNe, providing a natural explanation for their modest luminosities and strong circumstellar interaction.

2. 10–90 M☉ (Fe‑core Collapse SNe) – Conventional core‑collapse supernovae dominate this interval. The paper emphasizes that spherical explosion models cannot reproduce the detailed abundance patterns observed in extremely metal‑poor (EMP) stars, especially the elevated