Galactic Chemical Evolution of Radioactive Isotopes with an s-process Contribution

Trueman, Thomas C. L.; Côté, Benoit; Yagüe López, Andrés; Den Hartogh, Jacqueline; Pignatari, Marco; Soós, Benjámin; Karakas, Amanda I.; Lugaro, Maria

Abstract

Analysis of inclusions in primitive meteorites reveals that several short-lived radionuclides (SLRs) with half-lives of 0.1-100 Myr existed in the early solar system (ESS). We investigate the ESS origin of 107Pd, 135Cs, and 182Hf, which are produced by slow neutron captures (the s-process) in asymptotic giant branch (AGB) stars. We modeled the Galactic abundances of these SLRs using the OMEGA+ galactic chemical evolution (GCE) code and two sets of mass- and metallicity-dependent AGB nucleosynthesis yields (Monash and FRUITY). Depending on the ratio of the mean-life τ of the SLR to the average length of time between the formations of AGB progenitors γ, we calculate timescales relevant for the birth of the Sun. If τ/γ ⪆ 2, we predict self-consistent isolation times between 9 and 26 Myr by decaying the GCE predicted 107Pd/108Pd, 135Cs/133Cs, and 182Hf/180Hf ratios to their respective ESS ratios. The predicted 107Pd/182Hf ratio indicates that our GCE models are missing 9%-73% of 107Pd and 108Pd in the ESS. This missing component may have come from AGB stars of higher metallicity than those that contributed to the ESS in our GCE code. If τ/γ ≲ 0.3, we calculate instead the time (T LE) from the last nucleosynthesis event that added the SLRs into the presolar matter to the formation of the oldest solids in the ESS. For the 2 M o˙, Z = 0.01 Monash model we find a self-consistent solution of T LE = 25.5 Myr.

Citation

Trueman, T. C. L., Côté, B., Yagüe López, A., Den Hartogh, J., Pignatari, M., Soós, B., …Lugaro, M. (2022). Galactic Chemical Evolution of Radioactive Isotopes with an s-process Contribution. The Astrophysical journal, 924(1), 10. https://doi.org/10.3847/1538-4357/ac31b0

• Journal Article Type: Article
• Acceptance Date: Oct 20, 2021
• Online Publication Date: Jan 5, 2022
• Publication Date: Jan 1, 2022
• Deposit Date: Jan 22, 2022
• Publicly Available Date: Jan 24, 2022
• Journal: Astrophysical Journal
• Print ISSN: 0004-637X
• Electronic ISSN: 1538-4357
• Publisher: American Astronomical Society
• Peer Reviewed: Peer Reviewed
• Volume: 924
• Issue: 1
• Pages: 10
• DOI: https://doi.org/10.3847/1538-4357/ac31b0
• Keywords: Space and Planetary Science; Astronomy and Astrophysics
• Public URL: https://hull-repository.worktribe.com/output/3916147
• Additional Information: Article Title: Galactic Chemical Evolution of Radioactive Isotopes with an s-process Contribution; Journal Title: The Astrophysical Journal; Article Type: paper; Copyright Information: © 2022. The Author(s). Published by the American Astronomical Society.; Date Received: 2021-04-30; Date Accepted: 2021-10-19; Online publication date: 2022-01-05