2021ApJ...910...24C

We explore changes in the adiabatic low-order g-mode pulsation periods of 0.526, 0.560, and 0.729 M_☉ carbon-oxygen white dwarf models with helium-dominated envelopes due to the presence, absence, and enhancement of ²²Ne in the interior. The observed g-mode pulsation periods of such white dwarfs are typically given to 6-7 significant figures of precision. Usually white dwarf models without ²²Ne are fit to the observed periods and other properties. The rms residuals to the ≃150-400 s low-order g-mode periods are typically in the range of σ_rms <= 0.3 s, for a fit precision of σ_rms/P <= 0.3%. We find average relative period shifts of ΔP/P ≃ ±0.5% for the low-order dipole and quadrupole g-mode pulsations within the observed effective temperature window, with the range of ΔP/P depending on the specific g-mode, abundance of ²²Ne, effective temperature, and the mass of the white dwarf model. This finding suggests a systematic offset may be present in the fitting process of specific white dwarfs when ²²Ne is absent. As part of the fitting processes involves adjusting the composition profiles of a white dwarf model, our study on the impact of ²²Ne can provide new inferences on the derived interior mass fraction profiles. We encourage routinely including ²²Ne mass fraction profiles, informed by stellar evolution models, to future generations of white dwarf model-fitting processes.