Search

In this study, new CCD photometric observations and photometric analysis of BK Vul and V699 Cep systems, which are classified as contact binaries in the literature, are presented. For the V699 Cep, the TESS light curve was also used in the photometric analysis. We determined the basic astrophysical parameters of the BK Vul and V699 Cep systems from photometric analysis using the Wilson–Devinney method. Due to the lack of spectroscopic data for both systems in the literature, these absolute parameters were approximately calculated as to be M 2 = 0.73 M ⊙ , R 1 = 1.39 R ⊙ and R 2 = 1.09 R ⊙ for BK Vul, and M 2 = 0.36 M ⊙ , R 1 = 2.40 R ⊙ and R 2 = 1.33 R ⊙ for V699 Cep after estimating the mass of the primary component. The period decrease rate (dP/dt) and cyclic variation period of BK Vul were determined from the O − C analysis as -3.86 × 1 0 − 7 day yr−1 and 27 yrs., respectively. The evolutionary status of components of both systems were discussed. • The first photometric analysis of the eclipsing binary BK Vul and V699 Cep. • BK Vul and V699 Cep are A-subtype contact binary systems. • New minimum times were obtained. • The absolute physical parameters of the components of both systems are estimated. [ABSTRACT FROM AUTHOR]

Abstract: Our statistical analysis shows that, because of the three-body effects, the classical double two-body model cannot be used to describe the kinematics of most hierarchical triple star systems with the precision of present day observations (1 mas). Even for the usual practical requirements, this model is not suitable for figuring those systems suffering significant three-body effects. Because it is not practical to use numerical ephemerides with a large volume of data to describe the kinematics of component stars in a star catalogue, a kinematical model as simple and practical as possible for the hierarchical triple star systems is needed. Based on the existing observations and their associated fitting results, we obtain consistent mass parameters and initial conditions of six hierarchical triple star systems. Then the description of the kinematics of these systems on the basis of practical requirements is discussed. [Copyright &y& Elsevier]