期刊
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
卷 504, 期 1, 页码 744-760出版社
OXFORD UNIV PRESS
DOI: 10.1093/mnras/stab500
关键词
convection; hydrodynamics; nuclear reactions; nucleosynthesis; abundances; turbulence; stars: evolution; stars: interiors; stars: white dwarfs
资金
- NSERC
- National Science Foundation (USA) [PHY-1430152]
- Canadian Institute for Theoretical Astrophysics
- Klaus Tschira Stiftung
- NSF [1413548, AST-1814181]
- Division Of Astronomical Sciences
- Direct For Mathematical & Physical Scien [1413548] Funding Source: National Science Foundation
This study presents two mixing models for convective-reactive i-process nucleosynthesis in rapidly accreting white dwarfs, including a 1D advective two-stream model with physically motivated mixing coefficients and a simpler approach using diffusion coefficients calculated from simulations. The results show that in this particular application, the diffusion method provides a globally similar abundance distribution as the advective two-stream mixing model.
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 C-12(p, gamma)N-13 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 X-H 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, Kr-89 and Kr-90 with half-lives of and 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.
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