Asteroseismic analysis of 15 solar-like oscillating evolved stars

Abstract

Asteroseismology using space-based telescopes is vital to our understanding of stellar structure and evolution. {\textit{CoRoT}}, {\textit{Kepler}}, and {\textit{TESS}} space telescopes have detected large numbers of solar-like oscillating evolved stars. %(kaynaklar, Kallinger, vb ). Solar-like oscillation frequencies have an important role in the determination of fundamental stellar parameters; in the literature, the relations between the two is established by the so-called scaling relations. % These scaling relations are in better agreement with mass and radius of main-sequence stars with large separation ($\Delta\nu$) and frequency of maximum amplitude (${\nu_{\rm max}}$). In this study, we analyse data obtained from the observation of 15 evolved solar-like oscillating stars using the {\textit{Kepler}} and ground-based %\textit{CoRoT} telescopes. The main purpose of the study is to determine very precisely the fundamental parameters of evolved stars by constructing interior models using asteroseismic parameters. We also fit the reference frequencies of models to the observational reference frequencies caused by the He {\scriptsize II} ionization zone. The 15 evolved stars are found to have masses and radii within ranges of $0.79$-$1.47$ $M_{\rm sun}$ and $1.60$-$3.15$ $R_{\rm sun}$, respectively. Their model ages range from $2.19$ to $12.75$ Gyr. %Using a number of methods based on conventional and modified scaling relations and evolutionary models constructed with using the {\small {MESA}} code, we determine stellar radii, masses and ages. It is revealed that fitting reference frequencies typically increase the accuracy of asteroseismic radius, mass, and age. The typical uncertainties of mass and radius are $\sim$ 3-6 and $\sim$ 1-2 per cent, respectively. Accordingly, the differences between the model and literature ages are generally only a few Gyr.