Asteroseismic analysis of eight solar-like oscillating evolved stars in the open cluster NGC 6811

Abstract

The Kepler space telescope has provided exquisite data with which to perform asteroseismic analysis on evolved star ensembles. Studying star clusters offers significant insight into stellar evolution and structure, due to having a large number of stars with essentially the same age, distance, and chemical composition. This study analysed eight solar-like oscillating evolved stars that are members of the open cluster NGC 6811 and modelled them for the first time. The fundamental stellar parameters are obtained from the interior model using observational asteroseismic and non-asteroseismic constraints. The stellar interior models are constructed using the mesa evolution code. The mass-loss method is included in the interior models of the stars. The stellar masses and radius ranges of the stars are 2.23–2.40 M⊙ and 8.47–12.38 R⊙, respectively. Typical uncertainties for the mass and radius are ∼0.11 M⊙ and ∼0.09 R⊙, respectively. The model masses and radii are compared with masses and radii obtained from asteroseismic and non-asteroseismic methods (scaling relations and classic methods). The stellar ages fell in the range between 0.71 and 0.82 Gyr, with a typical uncertainty of ${\sim}18$ per cent. The model ages of the stars calculated in this study are compatible with those reported in the literature for NGC 6811.