3D Convective Urca Process in a Simmering White Dwarf
arXiv:2412.07938 · doi:10.3847/1538-4357/ad9bb0
Abstract
A proposed setting for thermonuclear (Type Ia) supernovae is a white dwarf that has gained mass from a companion to the point of carbon ignition in the core. In the early stages of carbon burning, called the simmering phase, energy released by the reactions in the core drive the formation and growth of a core convection zone. One aspect of this phase is the convective Urca process, a linking of weak nuclear reactions to convection, which may alter the composition and structure of the white dwarf. The convective Urca process is not well understood and requires 3D fluid simulations to properly model the turbulent convection, an inherently 3D process. Because the neutron excess of the fluid both sets and is set by the extent of the convection zone, the realistic steady state can only be determined in simulations with real 3D mixing processes. Additionally, the convection is relatively slow (Mach number less than 0.005) and thus a low Mach number method is needed to model the flow over many convective turnovers. Using the MAESTROeX low Mach number hydrodynamic software, we present the first full star 3D simulations of the A=23 convective Urca process, spanning hundreds of convective turnover times. Our findings on the extent of mixing across the Urca shell, the characteristic velocities of the flow, the energy loss rates due to neutrino emission, and the structure of the convective boundary can be used to inform 1D stellar models that track the longer-timescale evolution.
18 pages, 17 figures, Accepted to the Astrophysical Journal
References in corpus (26)
- Array Programming with NumPy
- Modules for Experiments in Stellar Astrophysics (MESA): Giant Planets, Oscillations, Rotation, and Massive Stars
- A Multi-Code Analysis Toolkit for Astrophysical Simulation Data
- Observational clues to the progenitors of Type-Ia supernovae
- The Statistics of Supersonic Isothermal Turbulence
- Turbulent Convection in Stellar Interiors. I. Hydrodynamic Simulation
- Carbon Ignition in Type Ia Supernovae: An Analytic Model
- Type Ia Supernova Explosions in Binary Systems: A Review
- The C-flame Quenching by Convective Boundary Mixing in Super-AGB Stars and the Formation of Hybrid C/O/Ne White Dwarfs and SN Progenitors
- Neutronization During Type Ia Supernova Simmering
- High-Resolution Simulations of Convection Preceding Ignition in Type Ia Supernovae Using Adaptive Mesh Refinement
- Electron capture and beta-decay rates for sd-shell nuclei in stellar environments relevant to high density O-Ne-Mg cores
- The Reduction of the Electron Abundance during the Pre-explosion Simmering in White Dwarf Supernovae
- Low Mach Number Modeling of Type Ia Supernovae. IV. White Dwarf Convection
- Hybrid C-O-Ne white dwarfs as progenitors of type Ia supernovae: dependence on Urca process and mixing assumptions
- Energy conservation and gravity waves in sound-proof treatments of stellar interiors: Part II Lagrangian constrained analysis
- A two-stream formalism for the convective Urca process
- 3D hydrodynamic simulations of massive main-sequence stars. I. Dynamics and mixing of convection and internal gravity waves
- The Convective Urca Process with Implicit Two-Dimensional Hydrodynamics
- Neutronization During Carbon Simmering In Type Ia Supernova Progenitors
- MAESTROeX: A Massively Parallel Low Mach Number Astrophysical Solver
- Type Ia Supernovae keep memory of their progenitor metallicity
- Dynamics in a stellar convective layer and at its boundary: Comparison of five 3D hydrodynamics codes
- pynucastro: an interface to nuclear reaction rates and code generator for reaction network equations
- Exploring the Carbon Simmering Phase: Reaction Rates, Mixing, and the Convective Urca Process
- Pre-explosive accretion and simmering phases of Type Ia Supernovae