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Abstract The cosmic evolution of the chemical elements from the Big Bang to the present time is driven by nuclear fusion reactions inside stars and stellar explosions. A cycle of matter recurrently re-processes metal-enriched stellar ejecta into the next generation of stars. The study of cosmic nucleosynthesis and this matter cycle requires the understanding of the physics of nuclear reactions, of the conditions at which the nuclear reactions are activated inside the stars and stellar explosions, of the stellar ejection mechanisms through winds and explosions, and of the transport of the ejecta towards the next cycle, from hot plasma to cold, star-forming gas. Due to the long timescales of stellar evolution, and because of the infrequent occurrence of stellar explosions, observational studies are challenging, as they have biases in time and space as well as different sensitivities related to the various astronomical methods. Here, we describe in detail the astrophysical and nuclear-physical processes involved in creating two radioactive isotopes useful in such studies, $$^{26}\mathrm{Al}$$ and $$^{60}\mathrm{Fe}$$ . Due to their radioactive lifetime of the order of a million years, these isotopes are suitable to characterise simultaneously the processes of nuclear fusion reactions and of interstellar transport. We describe and discuss the nuclear reactions involved in the production and destruction of $$^{26}\mathrm{Al}$$ and $$^{60}\mathrm{Fe}$$ , the key characteristics of the stellar sites of their nucleosynthesis and their interstellar journey after ejection from the nucleosynthesis sites. This allows us to connect the theoretical astrophysical aspects to the variety of astronomical messengers presented here, from stardust and cosmic-ray composition measurements, through observation of $$\gamma$$ rays produced by radioactivity, to material deposited in deep-sea ocean crusts and to the inferred composition of the first solids that have formed in the Solar System. We show that considering measurements of the isotopic ratio of $$^{26}\mathrm{Al}$$ to $$^{60}\mathrm{Fe}$$ eliminate some of the unknowns when interpreting astronomical results, and discuss the lessons learned from these two isotopes on cosmic chemical evolution. This review paper has emerged from an ISSI-BJ Team project in 2017–2019, bringing together nuclear physicists, astronomers, and astrophysicists in this inter-disciplinary discussion.
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This content will become publicly available on March 1, 2027
Nuclear astrophysics
Abstract Reactions between atomic nuclei are measured in great detail in terrestrial laboratory experiments; transferring and extrapolating this knowledge to how the same reactions act within cosmic environments presents major challenges. Cross-disciplinary efforts are needed in view of the many nuclear reactions that govern the chemical evolution of the universe, and occur in a broad range of stellar plasma conditions that require astrophysical exploration. The variety of quiescent and explosive astrophysical environments for nuclear processes reaches from Big Bang conditions through stellar interiors to a multitude of explosive processes of and near compact stars. Since the early identification of ’processes’ associated with the buildup of elements or nucleosynthesis, new insights have been obtained on the complexity of nuclear reaction mechanisms. This article will provide an overview in nuclear processing shaped by reactions during near equilibrium conditions, cooling and freeze out times. The emergence of molecular-like nucleon configurations within nuclei incurs important features at the low energies given in stellar interiors. Multiple capture and fusion reactions are key in the overall nucleosynthesis patterns. Here we use$$^{12}$$ C induced capture and fusion processes to illustrate the challenge of low-energy measurements and the challenges of using theoretical methods to extrapolate measurements towards energy regimes within cosmic sources. Slow and rapid neutron captures processes facilitate the gradual buildup of heavy elements. Particle beam experiments at accelerator facilities above and deep underground simulate stellar reactions, and new experimental facilities and methods complement these by providing short-lived isotope-separated beams and high-flux photon and neutron sources in a new generation of laboratories, with laser driven plasma facilities and particle storage rings as the latest tools for the experimenters. This is complemented by improved theoretical tools to calculate the quantum effects of nuclear reactions at the various cosmic conditions. Astronomical signatures of nuclear reactions from within cosmic sources are deduced through a growing range of observational tools. This ranges from the determination of rapidly changing light curves characterizing cosmic explosions from supernova, novae, and kilonovae, through gamma-ray lines and presolar grains to the detection of rare neutrino particles from our Sun to distant cosmic events. High resolution spectroscopy of distant stars has been expanded to objects and transient events measured in the X-ray and the gamma energy range of the electromagnetic spectrum. The analysis of vibrational behavior of stars in astro-seismology provides new tools in probing stellar interiors. The isotopic analysis of meteoritic inclusions provides detailed information about various nucleosynthesis sources, which are important tools for the understanding of complex dynamic convection and mixing processes in the interior of stars. While requiring care in interpreting observational data, to account for various biases and systematics, this variety of tools provides new opportunities and synergies. Chemical-evolution models provide a bridge through stellar-abundance archeology and have recently developed to also describe the complex dynamics during the evolution of galaxies. This article seeks to summarize the efforts to determine experimental and theoretical efforts for a better understanding of the complex mechanisms that lead to the compositional evolution of our universe, supplemented by an overview of the broad range of observational tools that have been developed to test the experimental data and the theoretical interpretation of nuclear processes in the cosmos.
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- Award ID(s):
- 2310059
- PAR ID:
- 10675117
- Publisher / Repository:
- Springer Nature
- Date Published:
- Journal Name:
- The European Physical Journal A
- Volume:
- 62
- Issue:
- 3
- ISSN:
- 1434-601X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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