On Trapped Modes in Variable White Dwarfs as Probes of the 12C(α, γ)16O Reaction Rate

Morgan T. Chidester, Ebraheem Farag, F. X. Timmes

Research output: Contribution to journalArticlepeer-review

Abstract

We seek signatures of the current experimental 12C α , γ 16 O reaction rate probability distribution function in the pulsation periods of carbon-oxygen white dwarf (WD) models. We find that adiabatic g-modes trapped by the interior carbon-rich layer offer potentially useful signatures of this reaction rate probability distribution function. Probing the carbon-rich region is relevant because it forms during the evolution of low-mass stars under radiative helium-burning conditions, mitigating the impact of convective mixing processes. We make direct quantitative connections between the pulsation periods of the identified trapped g-modes in variable WD models and the current experimental 12C α , γ 16 O reaction rate probability distribution function. We find an average spread in relative period shifts of ΔP/P ≃ ±2% for the identified trapped g-modes over the ±3σ uncertainty in the 12C α , γ 16 O reaction rate probability distribution function—across the effective temperature range of observed DAV and DBV WDs and for different WD masses, helium shell masses, and hydrogen shell masses. The g-mode pulsation periods of observed WDs are typically given to six to seven significant figures of precision. This suggests that an astrophysical constraint on the 12C α , γ 16 O reaction rate could, in principle, be extractable from the period spectrum of observed variable WDs.

Original languageEnglish (US)
Article number21
JournalAstrophysical Journal
Volume935
Issue number1
DOIs
StatePublished - Aug 1 2022

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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