Abstract

ABDELAZIZ, A. E. et al. An astrometric and photometric study of the intermediate-age open cluster NGC 2158 and its eclipsing binary [NBN2015]78. Rev. mex. astron. astrofis [online]. 2020, vol.56, n.2, pp.245-257.  Epub Mar 24, 2021. ISSN 0185-1101.  https://doi.org/10.22201/ia.01851101p.2020.56.02.07.

We present a photometric and astrometric analysis of the NGC 2158 cluster using Gaia DR2 and 2MASS data. The cluster age, color excess, intrinsic distance modulus and distance are calculated to be t = 2.240 ± 0.260Gyr, E(B − V ) =0.420±0.050mag, ${\left(m-M\right)}_{\odot }=12.540\pm 0.130mag$ and $d_{\text{⊙}}\text{=3224±200}pc$ respectively. The photometric analysis and light curve modelling of the proposed eclipsing binary member [NBN2015]78 is performed using the latest version of the WilsonDevinney (W-D) code. The solutions show that the system is an over-contact binary with a secondary component filling its Roche lobe, with a mass ratio q = 0.262. The primary and the secondary components of the system consist of two late spectral types K1 and K2 respectively. The membership of [NBN2015]78 is discussed using two independent methods, and we find that [NBN2015]78 is an interloper and not a member of NGC 2158.

Keywords : astrometry.