$\alpha$ Centauri A as a potential stellar model calibrator: establishing the nature of its core

TL;DR

This study investigates the energy transport in $$ Centauri A's core, showing that models fitting its revised mass suggest a convective core, which could make it a key calibrator for stellar physics.

Contribution

It demonstrates that $$ Centauri A likely has a convective core, supporting its use in calibrating stellar models, based on modeling with varied physics and observational constraints.

Findings

Most best-fit models indicate a convective core in $$ Centauri A.

The convective core presence is robust against different model physics.

Revised dynamical mass supports the star's role in calibration.

Abstract

Understanding the physical process responsible for the transport of energy in the core of $\alpha$ Centauri A is of the utmost importance if this star is to be used in the calibration of stellar model physics. Adoption of different parallax measurements available in the literature results in differences in the interferometric radius constraints used in stellar modelling. Further, this is at the origin of the different dynamical mass measurements reported for this star. With the goal of reproducing the revised dynamical mass derived by Pourbaix & Boffin, we modelled the star using two stellar grids varying in the adopted nuclear reaction rates. Asteroseismic and spectroscopic observables were complemented with different interferometric radius constraints during the optimisation procedure. Our findings show that best-fit models reproducing the revised dynamical mass favour the existence of a convective core ($\gtrsim$ 70% of best-fit models), a result that is robust against changes to the model physics. If this mass is accurate, then $\alpha$ Centauri A may be used to calibrate stellar model parameters in the presence of a convective core.