The i-process and CEMP-r/s stars

Herwig, F.; Ritter, C.; Woodward, P.; Bertolli, M.; Venn, K.; Denissenkov, P.; Jones, S.; Sandalski, S.; Higgs, C.; Heringer, E.; Prado, P.; Dardelet, L.; Pignatari, M.; Bertolli, Michael; Dardelet, Laurent; Denisenkov, P A; Higgs, Clare; Jones, Samuel; Masikiv Heringer, Epson Thiago; Prado, Pablo; Ritter, Christian; Sandalski, Stou; Venn, Kim

Abstract

© Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence. We investigate whether the anomalous elemental abundance patterns in some of the C-enhanced metal-poor-r/s (CEMP-r/s) stars are consistent with predictions of nucleosynthesis yields from the i-process, a neutron-capture regime at neutron densities intermediate between those typical for the slow (s) and rapid (r) processes. Conditions necessary for the i-process are expected to be met at multiple stellar sites, such as the He-core and He-shell flashes in low-metallicity low-mass stars, super-AGB and post-AGB stars, as well as low-metallicity massive stars. We have found that single-exposure one-zone simulations of the i-process reproduce the abundance patterns in some of the CEMP-r/s stars much better than the model that assumes a superposition of yields from s and r-process sources. Our previous study of nuclear data uncertainties relevant to the i-process revealed that they could have a significant impact on the i-process yields obtained in our idealized one-zone calculations, leading, for example, to ∼ 0:7dex uncertainty in our predicted [Ba/La] ratio. Recent 3D hydrodynamic simulations of convection driven by a He-shell flash in post-AGB Sakurai's object have discovered a new mode of non-radial instabilities: the Global Oscillation of Shell H-ingestion. This has demonstrated that spherically symmetric stellar evolution simulations cannot be used to accurately model physical conditions for the i-process.

Citation

Ritter, C., Dardelet, L., Prado, P., Heringer, E., Higgs, C., Sandalski, S., …Venn, K. The i-process and CEMP-r/s stars. Presented at Proceedings of Science

• Conference Name: Proceedings of Science
• Publication Date: Jan 1, 2014
• Deposit Date: Jan 4, 2016
• Publicly Available Date: Oct 27, 2022
• Journal: Proceedings of science
• Electronic ISSN: 1824-8039
• Peer Reviewed: Peer Reviewed
• Volume: 07-11-July-2015
• Keywords: i-process
• Public URL: https://hull-repository.worktribe.com/output/383711
• Publisher URL: Copy of paper from the conference Nuclei in the Cosmos XIII, 7-11 July, 2014, Debrecen, Hungary, published in Proceedings of science, http://pos.sissa.it/archive/conferences/204/145/NIC%20XIII_145.pdf