Journal
JOURNAL OF PHYSICS G-NUCLEAR AND PARTICLE PHYSICS
Volume 45, Issue 5, Pages -Publisher
IOP PUBLISHING LTD
DOI: 10.1088/1361-6471/aabb6e
Keywords
nuclear reactions; nucleosynthesis; stars: abundances; stars: AGB and post-AGB
Categories
Funding
- National Science Foundation [PHY-1430152, PHY-1102511]
- Hungarian Academy of Sciences
- SNF (Switzerland)
- NSERC
- Klaus Tschira Stiftung
- Canada Foundation for Innovation (CFI)
- ministere de l'Economie, de la science et de l'innovation du Quebec (MESI)
- Fonds de recherche du QuebecNature et technologies (FRQ-NT)
- Division Of Physics
- Direct For Mathematical & Physical Scien [1430152] Funding Source: National Science Foundation
- STFC [ST/R000840/1] Funding Source: UKRI
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The first-peak s-process elements Rb, Sr, Y and Zr in the post-AGB star Sakurai's object (V4334 Sagittarii) have been proposed to be the result of i-process nucleosynthesis in a post-AGB very-late thermal pulse event. We estimate the nuclear physics uncertainties in the i-process model predictions to determine whether the remaining discrepancies with observations are significant and point to potential issues with the underlying astrophysical model. We find that the dominant source in the nuclear physics uncertainties are predictions of neutron capture rates on unstable neutron rich nuclei, which can have uncertainties of more than a factor 20 in the band of the i-process. We use a Monte Carlo variation of 52 neutron capture rates and a 1D multi-zone post-processing model for the i-process in Sakurai's object to determine the cumulative effect of these uncertainties on the final elemental abundance predictions. We find that the nuclear physics uncertainties are large and comparable to observational errors. Within these uncertainties the model predictions are consistent with observations. A correlation analysis of the results of our MC simulations reveals that the strongest impact on the predicted abundances of Rb, Sr, Y and Zr is made by the uncertainties in the (n, gamma) reaction rates of Br-85, Br-86, Kr-87, Kr-88, Kr-89, Rb-89, Sr-89, and Sr-92. This conclusion is supported by a series of multi-zone simulations in which we increased and decreased to their maximum and minimum limits one or two reaction rates per run. We also show that simple and fast one-zone simulations should not be used instead of more realistic multi-zone stellar simulations for nuclear sensitivity and uncertainty studies of convective-reactive processes. Our findings apply more generally to any i-process site with similar neutron exposure, such as rapidly accreting white dwarfs with near-solar metallicities.
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