The core helium flash revisited: I. One and two-dimensional hydrodynamic simulations

Abstract

We investigate the hydrodynamics of the core helium flash near its peak. Past research concerned with the dynamics of this event is inconclusive. However, the most recent multidimensional hydrodynamic studies suggest a quiescent behavior and seem to rule out an explosive scenario. Previous work indicated, that depending on initial conditions, employed turbulence models, grid resolution, and dimensionality of the simulation, the core helium flash leads either to the disruption of a low-mass star or to a quiescent quasi-hydrostatic evolution. We try to clarify this issue by simulating the evolution with advanced numerical methods and detailed microphysics. Assuming spherical or axial symmetry, we simulate the evolution of the helium core of a $1.25M_{\odot }$ star with a metallicity Z=0.02 during the core helium flash at its peak with a grid-based hydrodynamics code. We find that the core helium flash neither rips the star apart, nor that it significantly alters its structure, as convection plays a crucial role in keeping the star in hydrostatic equilibrium. In addition, our simulations show the presence of overshooting, which implies new predictions concerning mixing of chemical species in red giants.

13 pages, 23 figures

References in corpus (8)

• Turbulent Convection in Stellar Interiors. I. Hydrodynamic Simulation
• Non-spherical Core Collapse Supernovae I. Neutrino-Driven Convection, Rayleigh-Taylor Instabilities, and the Formation and Propagation of Metal Clumps
• Non-Spherical Core-Collapse Supernovae II. Late-Time Evolution of Globally Anisotropic Neutrino-Driven Explosions and Implications for SN 1987A
• Simulating Self-gravitating Hydrodynamic Flows
• 3D Numerical Experimentation on the Core Helium Flash of low-mass Red Giants
• Anelastic and Compressible Simulations of Stellar Oxygen Burning
• On the helium flash in low-mass Population III Red Giant stars
• Age-luminosity relations for low-mass metal-poor stars

Cited by in corpus (28)

• Hot subluminous stars
• Preparing for an Explosion: Hydrodynamic Instabilities and Turbulence in Presupernovae
• Towards Realistic Progenitors of Core-Collapse Supernovae
• PARSEC V2.0: Stellar tracks and isochrones of low and intermediate mass stars with rotation
• Unstable Helium Shell Burning on Accreting White Dwarfs
• The Last Minutes of Oxygen Shell Burning in a Massive Star
• Solar structure and evolution
• The core helium flash revisited: II. Two and three-dimensional hydrodynamic simulations
• Wave-driven stellar expansion and binary interaction in pre-supernova outbursts
• Acoustic Signatures of the Helium Core Flash
• The chemical composition of carbon stars: The R-type stars
• When binaries keep track of recent nucleosynthesis: The Zr - Nb pair in extrinsic stars as an s-process diagnostic
• Shock-heating of stellar envelopes: A possible common mechanism at the origin of explosions and eruptions in massive stars
• Possible Implications of the Planet Orbiting the Red Horizontal Branch Star HIP 13044
• Evolutionary modelling of subdwarf B stars using MESA with the predictive mixing and convective premixing schemes
• The core helium flash revisited III. From Pop I to Pop III stars
• Gravitational settling in pulsating subdwarf B stars and their progenitors
• Stellar Evolution and Variability in the Pre-ZAHB Phase
• Multidimensional hydrodynamic simulations of the hydrogen injection flash
• New Post-AGB star models as tools to understand AGB evolution and nucleosynthesis
• Stochastic Core Spin-Up in Massive Stars -- Implications of 3D Simulations of Oxygen Shell Burning
• Presupernova Structure of Massive Stars
• Seismic characterization of red giants going through the Helium-core flash
• Hydrodynamic simulations of shell convection in stellar cores
• Recent Advances in Modeling Stellar Interiors
• Neutrinos and Asteroseismology of Stars over the Helium Flash
• Asteroseismic Constraints on the Models of Hot B Subdwarfs: Convective Helium-Burning Cores
• Detection horizon for the neutrino burst from the stellar helium flash