i-process Nucleosynthesis and Mass Retention Efficiency in He-shell Flash Evolution of Rapidly Accreting White Dwarfs

Denissenkov, Pavel A.; Herwig, Falk; Battino, Umberto; Ritter, Christian; Pignatari, Marco; Jones, Samuel; Paxton, Bill

Abstract

© 2017. The American Astronomical Society. All rights reserved. Based on stellar evolution simulations, we demonstrate that rapidly accreting white dwarfs (WDs) in close binary systems are an astrophysical site for the intermediate neutron-capture process. During recurrent and very strong He-shell flashes in the stable H-burning accretion regime H-rich material enters the He-shell flash convection zone. 12 C(p, γ) 13 N reactions release enough energy to potentially impact convection, and i process is activated through the 13 C(α, n) 16 O reaction. The H-ingestion flash may not cause a split of the convection zone as it was seen in simulations of He-shell flashes in post-AGB and low-Z asymptotic giant branch (AGB) stars. We estimate that for the production of first-peak heavy elements this site can be of similar importance for galactic chemical evolution as the s-process production by low-mass AGB stars. The He-shell flashes result in the expansion and, ultimately, ejection of the accreted and then i-process enriched material, via super-Eddington-luminosity winds or Roche-lobe overflow. The WD models do not retain any significant amount of the accreted mass, with a He retention efficiency of ≲ 10% depending on mass and convective boundary mixing assumptions. This makes the evolutionary path of such systems to supernova Ia explosion highly unlikely.

Citation

Denissenkov, P. A., Herwig, F., Battino, U., Ritter, C., Pignatari, M., Jones, S., & Paxton, B. (2017). i-process Nucleosynthesis and Mass Retention Efficiency in He-shell Flash Evolution of Rapidly Accreting White Dwarfs. Astrophysical journal. Letters, 834(2), L10. https://doi.org/10.3847/2041-8213/834/2/l10

• Journal Article Type: Article
• Acceptance Date: Dec 9, 2016
• Online Publication Date: Jan 9, 2017
• Publication Date: Jan 9, 2017
• Deposit Date: Feb 7, 2017
• Publicly Available Date: Feb 7, 2017
• Journal: Astrophysical journal letters
• Print ISSN: 2041-8205
• Publisher: American Astronomical Society
• Peer Reviewed: Peer Reviewed
• Volume: 834
• Issue: 2
• Article Number: ARTN L10
• Pages: L10
• DOI: https://doi.org/10.3847/2041-8213/834/2/l10
• Keywords: Space and Planetary Science; Astronomy and Astrophysics
• Public URL: https://hull-repository.worktribe.com/output/447858
• Publisher URL: http://iopscience.iop.org/article/10.3847/2041-8213/834/2/L10/meta;jsessionid=88C3F3206484B771AFA85564E246EE33.ip-10-40-1-105
• Additional Information: Journal title: The Astrophysical Journal; Article type: paper; Article title: i-process Nucleosynthesis and Mass Retention Efficiency in He-shell Flash Evolution of Rapidly Accreting White Dwarfs; Copyright information: © 2017. The American Astronomical Society. All rights reserved.; Date received: 2016-10-26; Date accepted: 2016-12-09; Online publication date: 2017-01-09
• Contract Date: Feb 7, 2017