Year: 2025
Type: article
Abstract: Cooling ages of white dwarfs are routinely determined by mapping effective temperatures and masses to ages using evolutionary models. Typically, the reported uncertainties on cooling ages only consider the error propagation of the uncertainties on the spectroscopically or photometrically determined T eff and mass. However, cooling models are themselves uncertain, given their dependence on many poorly constrained inputs. This paper estimates these systematic model uncertainties. We use MESA to generate cooling sequences of 0.5–1.0 M ⊙ hydrogen-atmosphere white dwarfs with carbon–oxygen cores under different assumptions regarding the chemical stratification of their core, the thickness of their helium envelope, their hydrogen content, and the conductive opacities employed in the calculations. The parameter space explored is constrained by the range of values predicted by a variety of stellar evolution models and inferred from asteroseismological studies. For a 0.6 M ⊙white dwarf, we find an uncertainty of 0.03 Gyr at 10,000 K (corresponding to a 5% relative uncertainty) and 0.8 Gyr at 4000 K (9%). This uncertainty is significant, as it is comparable to the age uncertainty obtained by propagating the measurement errors on T eff and mass for a typical white dwarf. We also separately consider the potential impact of 22Ne shell distillation, which plausibly leads to an additional uncertainty of ∼1 Gyr for crystallized white dwarfs. We provide a table of our simulation results that can be used to evaluate the systematic model uncertainty based on a white dwarf’s T eff and mass. We encourage its use in all future studies where white dwarf cooling ages are measured.
Source: The Astrophysical Journal
Authors: Praneet Pathak, Simon Blouin, Falk Herwig
Institution: University of Victoria
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $4,499
OpenAlex ID: W4409519603