Asteroseismology of KIC 8263801:Is it a member of NGC 6866 and a red clump star?

TL;DR

This study uses asteroseismology to determine the evolutionary stage and cluster membership of KIC 8263801, revealing it is a red giant branch star not belonging to NGC 6866.

Contribution

The paper demonstrates how asteroseismic analysis can accurately distinguish red giant branch stars from red clump stars and assess cluster membership.

Findings

KIC 8263801 is on the ascending red giant branch.

It is not a member of NGC 6866.

The star has a mass of approximately 1.79 solar masses.

Abstract

We present an asteroseismic analysis of the Kepler light curve of KIC 8263801, a red-giant star in the open cluster NGC 6866 that has previously been reported to be a helium-burning red-clump star. We extracted the frequencies of the radial and quadrupole modes from its frequency power spectrum and determined its properties using a grid of evolutionary models constructed with MESA. The oscillation frequencies were calculated using the GYRE code and the surface term was corrected using the Ball & Gizon(2014) prescription. We find that the star has a mass of $M/M_{\odot} = 1.793\pm 0.072$, age $t=1.48\pm 0.21$ Gyr and radius $R/R_{\odot} = 10.53\pm 0.28$. By analyzing the internal structure of the best-fitting model, we infer the evolutionary status of the star KIC 8263801 as being on the ascending part of the red giant branch, and not on the red clump. This result is verified using a purely asteroseismic diagnostic, the $\epsilon_{c}-\Delta\nu_{c}$ diagram which can distinguish red giant branch stars from red clump stars. Finally, by comparing its age with NGC 6866 ($t=0.65 \pm 0.1$ Gyr) we conclude that KIC 8263801 is not a member of this open cluster.