V957 CEP—A Zero-Age Eclipsing System

Abstract

New high-precision photometric measurements of the V957 Cep system (\(P{{ = 1.99}^{d}}\), \(V{{ = 11.17}^{m}}\), \(e = 0.127\), B6 V+B8 V), as well as an integrated approach to determining orbital parameters based both on photometric solutions of the light curves and the study of the course of residual deviations of the minima timings from the linear formula \(O - C\) made it possible for the first time to accurately measure the apsidal motion rate: \({{\dot {\omega }}_{{{\text{obs}}}}} = 2.91^\circ \)/year, which coincided with the theoretical value under the condition of the orbital and axial rotation synchronism: \({{\dot {\omega }}_{{{\text{theor}}}}} = 2.92^\circ \)/year. The physical parameters of the component stars were obtained: \({{T}_{1}} = 14\,550 \pm 300\) K, \({{M}_{1}} = 4.0 \pm 0.2{\kern 1pt} {{M}_{ \odot }}\), \({{R}_{1}} = 2.55 \pm 0.05{\kern 1pt} {{R}_{ \odot }}\), \({{T}_{2}} = 12\,400 \pm 250\) K, M₂ = 3.0 ± \(0.15{\kern 1pt} {{M}_{ \odot }}\), \({{R}_{2}} = 1.88 \pm 0.05{\kern 1pt} {{R}_{ \odot }}\). This set of parameters corresponds to stars of zero age, recently descended to ZAMS. The secondary component is a pulsating variable star of the \(\beta \) Cephei type.