The i-process and CEMP-r/s stars

Dardelet, L.; Ritter, C.; Prado, P.; Heringer, E.; Higgs, C.; Sandalski, S.; Jones, S.; Denissenkov, P.; Venn, K.; Bertolli, M.; Woodward, P.; Herwig, F.; 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., Jones, S., Denissenkov, P., Venn, K., Bertolli, M., Woodward, P., Herwig, F., Pignatari, M., Bertolli, M., Dardelet, L., Denisenkov, P. A., Higgs, C., Jones, S., Masikiv Heringer, E. T., Prado, P., …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: Nov 23, 2017
• 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
• Contract Date: Nov 23, 2017