Thorough characterisation of the 16 Cygni system. Part II. Seismic inversions of the internal structure

TL;DR

This study applies seismic inversion techniques to the 16 Cygni binary system to refine internal structure models, confirming previous results and highlighting the need for non-linear inversions and additional chemical abundance analyses for deeper insights.

Contribution

It extends prior modeling by applying linear seismic inversions to 16 Cygni, assessing their limitations, and emphasizing the necessity of non-linear methods and chemical depletion studies for improved stellar modeling.

Findings

Linear seismic inversions cannot distinguish standard from non-standard models.

Results confirm previous modeling robustness.

Non-linear inversions and chemical depletion analyses are needed for further insights.

Abstract

The advent of space-based photometry observations provided high-quality asteroseismic data for a large number of stars. These observations enabled the adaptation of advanced techniques, until then restricted to helioseismology, to study the best asteroseismic targets. Amongst these, the 16Cyg binary system holds a special place, being the brightest solar twins observed by Kepler. For this system, modellers have access to high-quality asteroseismic, spectroscopic and interferometric data, making it the perfect testbed for the limitations of stellar models. We aim to further constrain the internal structure and fundamental parameters of 16CygA&B using linear seismic inversion techniques of both global indicators and localised corrections of the internal structure. We start from the models defined by detailed modelling in our previous paper and extend our analysis by applying variational inversions to these models. We carried out inversions of so-called seismic indicators and provided local corrections of the internal structure of the two stars. Our results indicate that linear seismic inversions alone are not able to discriminate between standard and non-standard models for 16CygA&B. We confirm the results of our previous studies that used linear inversion techniques, but consider that the differences could be linked to small fundamental parameters variations rather than to a missing process in the models. We confirm the robustness and reliability of the results of the modelling performed in our previous paper. We conclude that non-linear inversions are likely required to further investigate the properties of 16CygA&B from a seismic point of view, but that these inversions should be coupled to analyses of the depletion of light elements such as lithium and beryllium to constrain the macroscopic transport of chemicals and potential non-standard evolutionary paths.