Cococubed.com KIC 08626021 a variable white dwarf
Home Astronomy research   Software Infrastructure:      MESA      FLASH      STARLIB      MESA-Web      starkiller-astro      My instruments   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   Stars:      Pulsating white dwarfs      Pop III with JWST      Monte Carlo massive stars      Neutrinos from pre-SN      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:      Iron Pseudocarbynes      Radionuclides in the 2020s      Hypatia catalog      Zone models H to Zn      Mixing ejecta      γ-rays within 100 Mpc   Thermodynamics & Networks      Stellar EOS      12C(α,γ)16O Rate      Proton-rich NSE      Reaction networks      Bayesian reaction rates   Verification Problems:      Validating an astro code      Su-Olson      Cog8      Mader      RMTV      Sedov      Noh Software instruments Presentations Illustrations YouTube: cococubed Bicycle adventures Public Outreach Education materials AAS Journals YouTube: AAS 2019 JINA R-process Workshop 2020 Digital Infrastructure 2020 MESA Marketplace 2020 MESA Summer School 2020 ASU Solar Systems 2020 ASU Energy in Everyday Life Contact: F.X.Timmes my one page vitae, full vitae, research statement, and teaching statement.	The Impact of White Dwarf Luminosity Profiles on Oscillation Frequencies (2018) KIC 08626021 is a pulsating DB white dwarf of considerable recent interest, and first of its class to be extensively monitored by Kepler for its pulsation properties. Fitting the observed oscillation frequencies of KIC 08626021 to a model can yield insights into its otherwise-hidden internal structure. Template-based white dwarf models choose a luminosity profile where the luminosity is proportional to the enclosed mass, $L_r \propto M_r$, independent of the effective temperature $T_{\rm eff}$. Evolutionary models of young white dwarfs with $T_{\rm eff} \gtrsim$ 25,000 K suggest neutrino emission gives rise to luminosity profiles with $L_r$ $\not\propto$ $M_r$. In this article we explore this contrast by comparing the oscillation frequencies between two nearly identical white dwarf models: one with an enforced $L_r \propto M_r$ luminosity profile and the other with a luminosity profile determined by the star's previous evolution history. We find the low order g-mode frequencies differ by up to $\simeq$ 70 $\mu$Hz over the range of Kepler observations for KIC 08626021. This suggests that by neglecting the proper thermal structure of the star (e.g., accounting for the effect of plasmon neutrino losses), the model frequencies calculated by using an $L_r \propto M_r$ profile may have uncorrected, effectively-random errors at the level of tens of $\mu$Hz. A mean frequency difference of 30 $\mu$Hz, based on linearly extrapolating published results, suggests a template model uncertainty in the fit precision of $\simeq$ 12% in white dwarf mass, $\simeq$ 9% in the radius, and $\simeq$ 3% in the central oxygen mass fraction. white dwarf structure propagation diagram mode frequency differences weight function shifts white dwarf cooling