An astrometric and photometric study of the young open cluster NGC 2168 and its possible member [NBN2015]77

Abstract

We present an astrometric and photometric study of the young open star cluster NGC 2168 and its proposed member [NBN2015]77. NGC 2168 was investigated by combining data from both the Gaia-ESO DR2 and the 2MASS databases. The photometric analysis and light curve modeling of the W UMa star [NBN2015] 77 in V and R bands was performed using the Wilson-Devinney (W-D) program. The cluster's main parameters: its distance, color excess, and age ared=862±67pc, E(B−V)=0.290±0.049, and 126 Myr, respectively. Our results show that the system [NBN2015] 77 is a W UMA eclipsing binary of A-subtype, with a low mass ratio of 0.231±0.023, and two components are of spectral types A7 and A9. The physical parameters of both components of the binary were estimated. Using two independent means we discuss the membership of [NBN2015] 77 and find that [NBN2015] 77 is a background field star and not a member of NGC 2168.