Model-independent measurement of internal stellar structure in 16 Cygni A and B

TL;DR

This paper introduces a model-independent asteroseismic method called 'inversions for agreement' to measure internal stellar structures, specifically sound speeds in 16 Cygni A and B, revealing discrepancies with existing models.

Contribution

The paper presents a novel inversion technique that accurately measures stellar core properties without relying on stellar models, improving understanding of stellar interiors.

Findings

Measured core sound speeds exceed model predictions.

Method accounts for uncertainties in stellar mass and radius.

Results are independent of specific stellar models.

Abstract

We present a method for measuring internal stellar structure based on asteroseismology that we call "inversions for agreement." The method accounts for imprecise estimates of stellar mass and radius as well as the relatively limited oscillation mode sets that are available for distant stars. By construction, the results of the method are independent of stellar models. We apply this method to measure the isothermal sound speeds in the cores of the solar-type stars 16 Cyg A and B using asteroseismic data obtained from Kepler observations. We compare the asteroseismic structure that we deduce against best-fitting evolutionary models and find that the sound speeds in the cores of these stars exceed those of the models.