The Effects of Curvature and Expansion on Helium Detonations on White Dwarf Surfaces

Abstract

Accreted helium layers on white dwarfs have been highlighted for many decades as a possible site for a detonation triggered by a thermonuclear runaway. In this paper, we find the minimum helium layer thickness that will sustain a steady laterally propagating detonation and show that it depends on the density and composition of the helium layer, specifically C12 and O16. Detonations in these thin helium layers have speeds slower than the Chapman-Jouget (CJ) speed from complete helium burning, v_cj=1.5e9 cm/s. Though gravitationally unbound, the ashes still have unburned helium (~ 80% in the thinnest cases) and only reach up to heavy elements such as Ca40, Ti44, Cr48, and Fe52. It is rare for these thin shells to generate large amounts of Ni56. We also find a new set of solutions that can propagate in even thinner helium layers when O16 is present at a minimum mass fraction of ~0.07. Driven by energy release from alpha captures on O16 and subsequent elements, these slow detonations only create ashes up to Si28 in the outer detonated He shell. We close by discussing how the unbound helium burning ashes may create faint and fast ".Ia" supernovae as well as events with virtually no radioactivity, and speculate on how the slower helium detonation velocities impact the off-center ignition of a carbon detonation that could cause a Type Ia supernova in the double detonation scenario.

arXiv comment21 pages, 33 figures. Accepted to ApJ - 08/19/2013

References in corpus (33)

• Modules for Experiments in Stellar Astrophysics (MESA)
• Modules for Experiments in Stellar Astrophysics (MESA): Giant Planets, Oscillations, Rotation, and Massive Stars
• Astrophysical Reaction Rates From Statistical Model Calculations
• Double-detonation sub-Chandrasekhar supernovae: can minimum helium shell masses detonate the core?
• Faint Thermonuclear Supernovae from AM Canum Venaticorum Binaries
• Type Iax Supernovae: A New Class of Stellar Explosion
• On Variations in the Peak Luminosity of Type Ia Supernovae
• Sub-Chandrasekhar Mass Models For Type Ia Supernovae
• Helium-ignited violent mergers as a unified model for normal and rapidly declining Type Ia Supernovae
• Surface Detonations in Double Degenerate Binary Systems Triggered by Accretion Stream Instabilities
• The Long-Term Evolution of Double White Dwarf Mergers
• The ELM Survey. I. A Complete Sample of Extremely Low Mass White Dwarfs
• Thermonuclear .Ia Supernovae from Helium Shell Detonations: Explosion Models and Observables
• Unstable Helium Shell Burning on Accreting White Dwarfs
• 2D simulations of the double-detonation model for thermonuclear transients from low-mass carbon-oxygen white dwarfs
• Rapidly Decaying Supernova 2010X: A Candidate ".Ia" Explosion
• The ELM Survey. II. Twelve Binary White Dwarf Merger Systems
• An Unusually Fast-Evolving Supernova
• Helium Shell Detonations on Low Mass White Dwarfs as a Possible Explanation for SN 2005E
• The Fast and Furious Decay of the Peculiar Type Ic Supernova 2005ek
• Mapping Initial Hydrostatic Models in Godunov Codes
• The ELM Survey. IV. 24 White Dwarf Merger Systems
• The ELM Survey. V. Merging Massive White Dwarf Binaries
• The Viscous Evolution of White Dwarf Merger Remnants
• The ELM Survey. III. A Successful Targeted Survey for Extremely Low Mass White Dwarfs
• Multi-Dimensional Double Detonation of Sub-Chandrasekhar Mass White Dwarfs
• The shortest period sdB plus white dwarf binary CD-30 11223 (GALEX J1411-3053)
• Laterally Propagating Detonations in Thin Helium Layers on Accreting White Dwarfs
• An Emerging Class of Bright, Fast-evolving Supernovae with Low-mass Ejecta
• Conditions For Successful Helium Detonations In Astrophysical Environments
• Initiation of the detonation in the gravitationally confined detonation model of Type Ia supernovae
• Local Ignition in Carbon/Oxygen White Dwarfs -- I: One-zone Ignition and Spherical Shock Ignition of Detonations
• Regimes Of Helium Burning

Cited by in corpus (31)

• The Evolution of Compact Binary Star Systems
• Sub-Chandrasekhar-mass white dwarf detonations revisited
• Type Ia Supernova Explosions in Binary Systems: A Review
• The Initiation and Propagation of Helium Detonations in White Dwarf Envelopes
• The Ignition of Carbon Detonations via Converging Shock Waves in White Dwarfs
• The Zwicky Transient Facility Census of the Local Universe I: Systematic search for Calcium rich gap transients reveal three related spectroscopic sub-classes
• He-Accreting WDs: accretion regimes and final outcomes
• Double Detonations with Thin, Modestly Enriched Helium Layers Can Make Normal Type Ia Supernovae
• The effect of helium accretion efficiency on rates of Type Ia supernovae: double-detonations in accreting binaries
• Explosive Nucleosynthesis in Sub-Chandrasekhar Mass White Dwarf Models for Type Ia Supernovae: Dependence on Model Parameters
• Multi-Dimensional Parameter Study of Double Detonation Type Ia Supernovae Originating from Thin-Helium-Shell White Dwarfs
• ZTF 18aaqeasu (SN 2018byg): A Massive Helium-shell Double Detonation on a Sub-Chandrasekhar Mass White Dwarf
• Multi-Dimensional Radiative Transfer Calculations of Double Detonations of Sub-Chandrasekhar-Mass White Dwarfs
• Nucleosynthesis in thermonuclear supernovae
• Diffuse Galactic antimatter from faint thermonuclear supernovae in old stellar populations
• A Tracer Method for Computing Type Ia Supernova Yields: Burning Model Calibration, Reconstruction of Thickened Flames, and Verification for Planar Detonations
• Reconciling 56Ni Production in Type Ia Supernovae with Double Degenerate Scenarios
• Smoothed Particle Hydrodynamics simulations of the core-degenerate scenario for Type Ia supernovae
• Sub-Chandrasekhar-mass detonations are in tension with the observed $t_0-M_{\text{Ni56}}$ relation of type Ia supernovae
• Gamma-ray bursts and kilonovae from the accretion-induced collapse of white dwarfs
• Multimessenger Emission from the Accretion Induced Collapse of White Dwarfs
• Type Ia Supernovae and their Environment: Theory and Applications to SN 2014J
• Surface and core detonations in rotating white dwarfs
• Quantifying How Density Gradients and Front Curvature Affect Carbon Detonation Strength During Type Ia Supernovae
• The Impact of Resolution on Double-Detonation Models for Type Ia Supernovae
• Prospects of direct detection of ${}^{48}$V gamma-rays from thermonuclear supernovae
• Confronting double-detonation sub-Chandrasekhar models with the low-luminosity suppression of Type Ia supernovae
• Local two-dimensional simulations of the ignition of a helium shell detonation on a white dwarf by an impacting stream
• Off-centre ignition of sub-Chandrasekhar white dwarfs does not resolve the tension with the observed $t_0$-$M_{\mathrm{Ni}56}$ relation of type Ia supernovae
• Can helium envelopes change the outcome of direct white dwarf collisions?
• Gamma-ray Signatures of r-Process Radioactivity from the Collapse of Magnetized White Dwarfs