3D hydrodynamic simulations of C ingestion into a convective O shell. Issue 1 (22nd October 2019)

• Record Type: Journal Article
• Authors: Andrassy, R; Herwig, F; Woodward, P; Ritter, C
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 491:Issue 1(2020)
• Page Start: 972
• Page End: 992
• Publication Date: 2019-10-22
• Subjects: convection -- hydrodynamics -- turbulence -- stars: evolution -- stars: interiors -- stars: massive; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/stz2952
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: Interactions between convective shells in evolved massive stars have been linked to supernova impostors, to the production of the odd-Z elements Cl, K, and Sc, and they might also help generate the large-scale asphericities that are known to facilitate shock revival in supernova explosion models. We investigate the process of ingestion of C-shell material into a convective O-burning shell, including the hydrodynamic feedback from the nuclear burning of the ingested material. Our 3D hydrodynamic simulations span almost 3 dex in the total luminosity L tot . All but one of the simulations reach a quasi-stationary state with the entrainment rate and convective velocity proportional to L tot and $L_\mathrm{tot}^{1/3}$, respectively. Carbon burning provides $14\!-\!33{{\ \rm per\ cent}}$ of the total luminosity, depending on the set of reactions considered. Equivalent simulations done on 768 3 and 1152 3 grids are in excellent quantitative agreement. The flow is dominated by a few large-scale convective cells. An instability leading to large-scale oscillations with Mach numbers in excess of 0.2 develops in an experimental run with the energy yield from C burning increased by a factor of 10. This run represents most closely the conditions expected in a violent O–C shell merger, which is a potential production site for odd-Z elements such as K and Sc and which may seed asymmetries in the supernova progenitor. 1D simulations may underestimate the energy generation from the burning of ingested material by as much as a factor 2 owing to their missing the effect of clumpiness of entrained material on the nuclear reaction rate.