Subsonic Burning Fronts (aka Flames)


Astronomy research
  Software Infrastructure:
     My codes
  White dwarf supernova:
     Remnant metallicities
     Colliding white dwarfs
     Merging white dwarfs
     Ignition conditions
     Metallicity effects
     Central density effects
     Detonation density effects
     Tracer particle burning
     Subsonic burning fronts
     Supersonic burning fronts
     W7 profiles
  Massive star supernova:
     Rotating progenitors
     3D evolution
     26Al & 60Fe
     44Ti, 60Co & 56Ni
     Yields of radionuclides
     Effects of 12C +12C
     SN 1987A light curve
     Constraints on Ni/Fe ratios
     An r-process
     Compact object IMF
     Pop III JWST
     Pre-SN variations
     Monte Carlo white dwarfs
     SAGB stars
     Classical novae
     He shell convection
     Presolar grains
     He burn on neutron stars
     BBFH at 40 years
  Chemical Evolution:
     Hypatia catalog
     Zone models H to Zn
     Mixing ejecta
     γ-rays within 100 Mpc
  Thermodynamics & Networks
     Stellar EOS
     Reaction networks
     Proton-rich NSE
     Bayesian reaction rates
  Verification Problems:
     Validating an astro code
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Teaching materials
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Contact: F.X.Timmes
my one page vitae,
full vitae,
research statement, and
teaching statement.
Turbulent Chemical Diffusion In Convectively Bounded Carbon Flames (2016)
It has been proposed that mixing induced by convective overshoot can disrupt the inward propagation of carbon deflagrations in super-asymptotic giant branch stars. To test this theory, in this paper by Lacoanet et al we study an idealized model of convectively bounded carbon flames with 3D hydrodynamic simulations of the Boussinesq equations using the pseudospectral code Dedalus. Because the flame propagation timescale is is much longer than the convection timescale, we approximate the flame as fixed in space, and only consider its effects on the buoyancy of the fluid. By evolving a passive scalar field, we derive a turbulent chemical diffusivity produced by the convection as a function of height, Dt(z). Convection can stall a flame if the chemical mixing timescale, set by the turbulent chemical diffusivity, Dt, is shorter than the flame propagation timescale, set by the thermal diffusivity, κ, i.e., when $\Dt > \kappa$. However, we find Dt < κ for most of the flame because convective plumes are not dense enough to penetrate into the flame. Extrapolating to realistic stellar conditions, this implies that convective mixing cannot stall a carbon flame and that ``hybrid carbon-oxygen-neon'' white dwarfs are not a typical product of stellar evolution.

Bouancy frequency
2D vertical slices

Dt versus height turbflame speeds

Propagation of Nuclear Flames IV (2007)
This paper explores how including the key neutron-rich isotope 22Ne changes the speed of laminar flames propagating through carbon-oxygen white dwarf.

flame speeds
Ye changes with 22Ne abundance

Propagation of Nuclear Flames III (2000)
How fast does a laminar flame from propagate through helium rich compositions? This paper explores some trends. I can't believe that I didn't publish the result that the final composition behind such flames is calcium, titanium, and chromium rich. Arrggh!

laminar helium flame
regimes in the rho-T plane
heating & cooling

Propagation of Nuclear Flames II (1994)
How fast does a laminar flame from propagate into degenerate oxygen, magnesium, and neon Ye=0.5 compositions when bounded by a convective region? We explore answers in this paper.

laminar ONeMg flame
balanced power curves
bounded flame speeds

Propagation of Nuclear Flames I (1992)
How fast does a laminar flame from propagate outward through degenerate carbon-oxygen and oxygen-neon-magnesium? We explore answers in this paper. These Ye=0.5 laminar flame speeds are used in many supernova type Ia models.

laminar oxygen-neon flame
carbon-oxygen flame speeds
density recovery

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