HD 214220 (BD+56 2813): An eclipsing binary with its primary component at the end of the main sequence

Abstract

Context. Analysis of the light curves of an eclipsing binary allows one to derive the absolute dimensions of the system. This in turn yields information on the radii of the components, which allows the stars to be accurately placed on the Hertzsprung-Russell diagram and their evolutionary phase to be interpreted via comparisons to tracks of stellar evolution models. Aims. I aim to derive the stellar and system parameters of HD 214220. Methods. I measured the epochs of three primary and three secondary minima of the eclipsing binary HD 214220 from 2019 to 2022 from photometric fluxes obtained by the TESS satellite. I modeled the light curve and the velocity amplitudes, which were obtained by the Gaia satellite, with the software PHOEBE. Results. HD 214220 is an eclipsing binary system with an orbital period of P = 43.14 d, eclipse depths of 17% and 13%, and masses of 2.49 M⊙ and 2.42 M⊙. The sum of the radii is R1 + R2 ≈ 8.5 R⊙, and the temperatures of the components are similar, with a ratio of T2/T1 ≈ 1.03. Conclusions. By consulting stellar evolution models, I find that the primary component has ended core hydrogen burning and is potentially in the contraction phase, prior to shell burning.