In a recent study, a team of researchers from the Konard Lorenz Institute of Evolution and Cognition, the University of Hull, the Monash Centre for Astrophysics, the Konkoly Observatory, and the INAF-Osservatorio Astronomico di Padova, led by Umberto Battino, has re-evaluated the impact of certain nuclear reactions on the production of the radioactive nuclide aluminum-26 in stars. This research, published in the journal Astronomy & Astrophysics, sheds light on the nucleosynthesis processes in both low- and high-mass stars, with potential implications for our understanding of stellar evolution and galactic chemistry.
Aluminum-26 is a short-lived radioactive isotope that plays a significant role in the evolution of stars and galaxies. However, the simulations of its production sites have been hindered by nuclear uncertainties. The research team focused on re-evaluating the reaction rates of two specific nuclear reactions involving aluminum-26: 26Al(n, p)26Mg and 26Al(n, α)23Na. These reactions were studied across a wide range of temperatures, from 0.01 GK to 10 GK, combining recent experimental measurements with theoretical predictions.
The researchers used three different stellar evolution and nucleosynthesis codes to test the impact of the new reaction rates on the production of aluminum-26 in stars. For low-mass stars, they found that the new reaction rates allowed models to reproduce the full range of 26Al/27Al ratios measured in meteoritic SiC grains. This suggests that the updated reaction rates provide a more accurate representation of the nucleosynthesis processes in low-mass asymptotic giant branch (AGB) stars.
For high-mass stars, the team tested the new reaction rates on two 15 solar mass models with different metallicities. They found that the final aluminum-26 abundance varied by a factor of 2.4 when adopting the upper or lower limit of the new reaction rates. This indicates that the updated reaction rates have a significant impact on the nucleosynthesis of high-mass stars, although stellar uncertainties still play a crucial role.
The practical applications of this research for the energy sector are indirect but noteworthy. Understanding the nucleosynthesis processes in stars contributes to our knowledge of the origin of elements, including those that are crucial for nuclear energy, such as uranium and thorium. Moreover, the study of stellar evolution and the production of radioactive isotopes can provide insights into the long-term behavior of nuclear waste and the potential for stellar-inspired nuclear processes on Earth.
In conclusion, the research team’s re-evaluation of the reaction rates for the production of aluminum-26 in stars has provided valuable insights into the nucleosynthesis processes in both low- and high-mass stars. The updated reaction rates improve our understanding of stellar evolution and galactic chemistry, with potential implications for the energy sector. The research was published in Astronomy & Astrophysics, a leading journal in the field of astronomy and astrophysics.
This article is based on research available at arXiv.