Abstract
We present two mixing models for post-processing of 3D hydrodynamic simulations applied to convective-reactive i-process nucleosynthesis in a rapidly accreting white dwarf (RAWD) with [Fe/H] =-2.6, in which H is ingested into a convective He shell. A 1D advective two-stream model adopts physically motivated radial and horizontal mixing coefficients constrained by 3D hydrodynamic simulations. A simpler approach uses diffusion coefficients calculated from the same simulations. All 3D simulations include the energy feedback of the 12C(p, γ)13N reaction from the H entrainment. Global oscillations of shell H ingestion in two of the RAWD simulations cause bursts of entrainment of H and non-radial hydrodynamic feedback. With the same nuclear network as in the 3D simulations, the 1D advective two-stream model reproduces the rate and location of the H burning within the He shell closely matching the 3D simulation predictions, as well as qualitatively displaying the asymmetry of the XH profiles between the upstream and downstream. With a full i-process network the advective mixing model captures the difference in the n-capture nucleosynthesis in the upstream and downstream. For example, 89Kr and 90Kr with half-lives of 3.18 min and 32.3 s differ by a factor 2-10 in the two streams. In this particular application the diffusion approach provides globally the same abundance distribution as the advective two-stream mixing model. The resulting i-process yields are in excellent agreement with observations of the exemplary CEMP-r/s star CS31062-050.
Original language | English (US) |
---|---|
Pages (from-to) | 744-760 |
Number of pages | 17 |
Journal | Monthly Notices of the Royal Astronomical Society |
Volume | 504 |
Issue number | 1 |
DOIs | |
State | Published - Jun 1 2021 |
Externally published | Yes |
Bibliographical note
Publisher Copyright:© 2021 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society.
Keywords
- convection
- hydrodynamics
- nuclear reactions, nucleosynthesis, abundances
- stars: evolution
- stars: interiors
- stars: white dwarfs
- turbulence