Nucleosynthesis in Stars and the Chemical Enrichment of Galaxies

TLDR

After the Big Bang, the first stars and their supernovae produced heavy elements, and their explosive feedback shaped subsequent star formation; the resulting nucleosynthesis signatures in extremely metal‑poor stars reveal peculiar abundance patterns that hint at the nature of these early stars. This review surveys recent nucleosynthesis yields from massive stars across a wide range of masses, metallicities, and explosion energies. The authors compile yield tables, examine how hydrodynamic effects such as explosion energy, mixing, fallback, and asphericity alter the yields, constrain these parameters with observations of supernovae and metal‑poor stars, and then apply the yields to chemical‑evolution models of the Milky Way and other galaxies. Applying the yields to galactic chemical‑evolution models clarifies how the chemical enrichment of the Galaxy and other galaxies proceeded during their evolution.

Abstract

After the Big Bang, production of heavy elements in the early Universe takes place starting from the formation of the first stars, their evolution, and explosion. The first supernova explosions have strong dynamical, thermal, and chemical feedback on the formation of subsequent stars and evolution of galaxies. However, the nature of the Universe's first stars and supernova explosions has not been well clarified. The signature of the nucleosynthesis yields of the first stars can be seen in the elemental abundance patterns observed in extremely metal-poor stars. Interestingly, those patterns show some peculiarities relative to the solar abundance pattern, which should provide important clues to understanding the nature of early generations of stars. We thus review the recent results of the nucleosynthesis yields of mainly massive stars for a wide range of stellar masses, metallicities, and explosion energies. We also provide yields tables and examine how those yields are affected by some hydrodynamical effects during supernova explosions, namely, explosion energies from those of hypernovae to faint supernovae, mixing and fallback of processed materials, asphericity, etc. Those parameters in the supernova nucleosynthesis models are constrained from observational data of supernovae and metal-poor stars. Nucleosynthesis yields are then applied to the chemical evolution model of our Galaxy and other types of galaxies to discuss how the chemical enrichment process occurred during evolution.