Merging White Dwarfs


Astronomy research
  Software Infrastructure:
     My instruments
  White dwarf pulsations:
     Probe of 12C(α,γ)16O
     Impact of 22Ne
     Impact of ν cooling
     Variable white dwarfs
     MC reaction rates
  White dwarf supernova:
     Stable nickel production
     Remnant metallicities
     Colliding white dwarfs
     Merging white dwarfs
     Ignition conditions
     Metallicity effects
     Central density effects
     Detonation density
     Tracer particle burning
     Subsonic burning fronts
     Supersonic fronts
     W7 profiles
  Massive stars:
     Pop III with HST/JWST
     Rotating progenitors
     3D evolution to collapse
     MC reaction rates
     Pre-SN variations
  Massive star supernova:
     Yields of radionuclides
     26Al & 60Fe
     44Ti, 60Co & 56Ni
     SN 1987A light curve
     Constraints on Ni/Fe
     An r-process
     Effects of 12C +12C
  Neutron Stars and Black Holes:
     Black Hole spectrum
     Mass Gap with LVK
     Compact object IMF
     He burn neutron stars
  Neutrino Emission:
     Identifying the Pre-SN
     Neutrino HR diagram
     Pre-SN Beta Processes
     Pre-SN neutrinos
     Hypatia catalog
     SAGB stars
     Nugrid Yields I
     He shell convection
     BBFH at 40 years
     γ-rays within 100 Mpc
     Iron Pseudocarbynes
  Pre-Solar Grains:
     C-rich presolar grains
     SiC Type U/C grains
     Grains from massive stars
     Placing the Sun
     SiC Presolar grains
  Chemical Evolution:
     Radionuclides in 2020s
     Zone models H to Zn
     Mixing ejecta
  Thermodynamics & Networks
     Skye EOS
     Helm EOS
     Five EOSs
     Equations of State
     12C(α,γ)16O Rate
     Proton-rich NSE
     Reaction networks
     Bayesian reaction rates
  Verification Problems:
     Validating an astro code
Software instruments
cococubed YouTube
Bicycle adventures
Public Outreach
Education materials
2023 ASU Solar Systems Astronomy
2023 ASU Energy in Everyday Life

AAS Journals
AAS YouTube
2023 MESA VI
2023 MESA Marketplace
2023 MESA Classroom
2022 Earendel, A Highly Magnified Star
2022 White Dwarfs & 12C(α,γ)16O
2022 Black Hole Mass Spectrum
2022 MESA in Don't Look Up
2021 Bill Paxton, Tinsley Prize

Contact: F.X.Timmes
my one page vitae,
full vitae,
research statement, and
teaching statement.
Spectra of Type Ia Supernovae from Double Degenerate Mergers (mergers II, 2012)
In this article we combine population synthesis, merger, and explosion models with radiation-hydrodynamics light-curve models to study the implications of such a progenitor scenario on the observed Type Ia supernova population. Our standard model, assuming double-degenerate mergers do produce thermonuclear explosions, produces supernova light curves that are broader than the observed type Ia sample. In addition, we discuss how the shock breakout and spectral features of these double-degenerate progenitors will differ from the canonical bare Chandrasekhar-massed explosion models. We conclude with a discussion of how one might reconcile these differences with current observations.

assumed profile
x-ray luminosities

Remnants of Binary White Dwarf Mergers (mergers I, 2010)
In this article we carry out a comprehensive smooth particle hydrodynamics simulation survey of double-degenerate white dwarf binary mergers of varying mass combinations in order to establish correspondence between initial conditions and remnant configurations. We find that all but one of our simulation remnants share general properties such as a cold, degenerate core surrounded by a hot disk, while our least massive pair of stars forms only a hot disk. We also find that some of our simulations with massive white dwarfs exhibit helium detonations on the surface of the primary star before complete disruption of the secondary. However, these helium detonations are insufficiently energetic to ignite carbon, and so do not lead to prompt carbon detonations.

initial conditions matter
0.8 + 0.8 Msun evolution
0.8 + 0.8 Msun, final configuration
0.8 + 0.8 Msun, x-z plane slice
0.96 + 1.06 Msun, He detonation
0.64+1.06 Msun, He detonation