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Exploring Proton Ingestion Episodes in Stellar Evolution: A Study of Dual Flashes

This study examines Proton Ingestion Episodes (PIEs) in stars, specifically focusing on dual core and shell flash phenomena. It discusses the convective mixing of protons into hotter regions, leading to significant nuclear reactions. The research employs the DJEHUTY code for three-dimensional modeling to analyze mixing processes, including neutron production and hydrogen burning in low metallicity stars. It contrasts traditional diffusion models with advanced 3D calculations, aiming to better understand the time-dependent mixing mechanics. Key results highlight the implications for nucleosynthesis and stellar evolution.

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Exploring Proton Ingestion Episodes in Stellar Evolution: A Study of Dual Flashes

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  1. Calculating PIEs with DJEHUTY Richard Stancliffe David Dearborn Stuart Heap Simon Campbell John Lattanzio

  2. PIE = Proton Ingestion Episode • Where convection mixes protons into a region that is much hotter than normal Hburning • Dual Core Flash • Dual Shell Flash

  3. Nomenclature • Lots of names for these events • Some ridiculous • HeFDDM-A/R = He Flash-driven Deep-mixing on the AGB or RGB • Simon Campbell’s thesis (also C&L 2010) • Dual Flashes • A He flash (core or shell) causes mixing of protons (PIE) • This results in a H flash • Dual Core Flash – mixing caused by core flash • Dual Shell Flash – mixing caused by shell flash • Both being examples of PIEs

  4. Dual Core Flash: Very low Z • Off-centre igntion • But strong convection • Mixing reaches H-rich envelope • Does not (?)happen at “normal” Z

  5. Neutron Super-burst!

  6. Dual Shell Flashes • For low Z stars on the AGB • PIE can occur

  7. PIEs • Expect neutron production • Expect s-processing • But how to calculate the time-dependent mixing? • Mostly treat mixing with diffusion equation • Mostly use MLT for values of v Wrong! Wrong!

  8. Try to do in 3D using DJEHUTY • Paper just submitted to ApJ • Dual shell flash • M=1 • Z=0.0001 • He shell flash convection reaches bottom of H-shell and ingests protons

  9. 1D input model

  10. 1D input model

  11. The 3D calculation (2 million zones) Bottom of H shell He-rich intershell CO core Top of He shell

  12. 1D value n-release exceeds 3a Luminosity variation/increase! 12C + p mostly….

  13. Density (on a slice) t=2.0hrs H shell He shell

  14. Temperature (on a slice) t=2.0hrs H shell He shell

  15. Hydrogen (on a slice) t=2.7hrs H shell He shell

  16. Hydrogen (on a slice) t=2.7hrs Downward plume

  17. 13N and v (in plane) (on a slice) t=2.7hrs N produced near the He shell

  18. Energy generation (on a slice) t=2.7hrs N produced near the He shell

  19. T variation (on a slice) t=2.7hrs Very minor! T-<T> --------   1% <T>

  20. Comparison to 1D: velocity profiles MLT x 10

  21. Comparison to 1D: H profiles

  22. 321D Theory (with Arnett et al) Vary up and down velocity in a 2-stream model…

  23. Show Movies • H1 • V_rad • e_nuc • N13

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