Asteroseismic modeling of 16 Cyg A & B using the complete Kepler data set

TL;DR

This study uses complete Kepler data to perform detailed asteroseismic modeling of 16 Cyg A & B, demonstrating precise age and composition estimates for binary stars and assessing the reliability of asteroseismic inference under various conditions.

Contribution

The paper provides an updated asteroseismic analysis of 16 Cyg A & B using the full Kepler data set and evaluates the accuracy and biases in stellar property estimation methods.

Findings

Both stars have an age of approximately 7.0 Gyr.

Estimated initial helium mass fraction may be biased low by 0.02-0.03.

Reliable stellar properties can be derived without independent radius and luminosity constraints.

Abstract

Asteroseismology of bright stars with well-determined properties from parallax measurements and interferometry can yield precise stellar ages and meaningful constraints on the composition. We substantiate this claim with an updated asteroseismic analysis of the solar-analog binary system 16 Cyg A & B using the complete 30-month data sets from the Kepler space telescope. An analysis with the Asteroseismic Modeling Portal (AMP), using all of the available constraints to model each star independently, yields the same age ($t=7.0 \pm 0.3$ Gyr) and composition ($Z=0.021 \pm 0.002$, $Y_i=0.25 \pm 0.01$) for both stars, as expected for a binary system. We quantify the accuracy of the derived stellar properties by conducting a similar analysis of a Kepler-like data set for the Sun, and we investigate how the reliability of asteroseismic inference changes when fewer observational constraints are available or when different fitting methods are employed. We find that our estimates of the initial helium mass fraction are probably biased low by 0.02-0.03 from neglecting diffusion and settling of heavy elements, and we identify changes to our fitting method as the likely source of small shifts from our initial results in 2012. We conclude that in the best cases reliable stellar properties can be determined from asteroseismic analysis even without independent constraints on the radius and luminosity.