Analysis of DQZ White Dwarf Evolution through Procyon

TL;DR

This study uses extensive stellar evolution modeling to analyze the Procyon binary system, constraining its age, progenitor mass, and white dwarf properties, and exploring the effects of metallicity, mixing length, and core overshoot.

Contribution

It provides a detailed grid of models for Procyon, revealing higher core overshoot and mapping the initial-to-final mass relationship for hydrogen-deficient white dwarfs.

Findings

Best-fit models match observed properties with system age ~2.2 Gyr.

White dwarf cooling age is approximately 1.2 Gyr.

Core overshoot parameter best fits range from 0.5 to 1.0.

Abstract

Procyon is a great system to probe stellar evolution of non-interacting binaries. We present an extensive grid of MESA (Modules for Experiments in Stellar Astrophysics) evolutionary tracks to constrain the evolution of Procyon A and B. We systematically vary the initial parameters of our grid anchored by precise dynamical masses and spectroscopic determinations of effective temperature (T$_{eff}$) and luminosity ($L$) to match the stars' positions on the H-R Diagram. Our goal is two-fold: (i) to quantify how the inferred system age and the progenitor mass of Procyon B depend on metallicity ($Z$), mixing length ($\alpha$), and core overshoot ($\beta$), and (ii) to determine the best fitting model of Procyon B within a model-based initial-to-final mass relationship (IMFR) for hydrogen-deficient white dwarfs. Our best-fit models reproduce the observed properties for both components, yielding $M_\mathrm{A}=1.487 \pm 0.095$ M$_{\odot}$, $M_\mathrm{B}=0.592\pm 0.082$ M$_{\odot}$, a system age of $2.23 \pm 0.90$ Gyr, and a white dwarf cooling age of $1.20\pm0.49$ Gyr for Procyon B, consistent with independent determinations. Our results point to higher core overshoot than the standard adopted range, with the best fits ranging from $\beta=0.5-1.0$. From our model grid, we map Procyon B to the initial-to-final mass relationship for H-deficient white dwarfs in the $1.9\!-\!2.6$ M$_{\odot}$ progenitor range. Additionally, we implement the accretion of heavy metals onto the surface of the WD and fit our isotopic abundances to spectroscopic observations. We outline the physics used in our analysis.