A comprehensive photometric and spectroscopic analysis of the variable TYC 5532-1333-1 (TYC) along with an investigation of its orbital period variation is presented for the first time. The B- and V-band photometric study indicates that TYC is an intermediate contact binary with degree of contact and mass ratio of 34 per cent and ∼0.24, respectively. The derived equivalent widths from the spectroscopic study of Hα and   Na-I lines reveal phase-dependent variation and mutual correlation. Using the available times of minimum light, an investigation of orbital period variation shows a long-term decrease at a rate of 3.98 × 10 −6 d yr−1. Expected causes for such decline in the orbital period could be angular momentum loss and a quasi-sinusoidal variation due to light-time effect probably caused by a third-body companion. The minimum mass of the third body (M3) was derived to be $0.65 \, \mathrm{M}_{\odot }$. Our presented study is an attempt to evaluate and understand the evolutionary state of above-mentioned neglected contact binary.

Study of eclipsing binaries in an open cluster offer information regarding the age of the cluster in addition to the component stars. In this paper we present the analysis of a W UMa system discovered in the open cluster NGC 6791 using the Wilson-Devinney (W-D) method.

We present photometric analysis of the two W UMa type binaries identified in the field of distant open star cluster NGC 6866. Although these systems, namely ID487 and ID494, were reported in the Joshi et al. (2012), but a detailed study of these stars has not been carried out earlier. The orbital periods of these stars are found to be 0.415110±0.000001 day and 0.366709±0.000004 day, respectively. Based on the photometric and infrared colours, we find their respective spectral types as K0 and K3. The photometric light variations of both the stars show O'Connell effect which could be explained by employing a dark spot on the secondary components. The V and I bands light curves are analyzed using the Wilson-Devinney (WD) code and relations given by Gazeas (2009) which yield radii and mass of the binary components of the star ID487 as R 1 = 1.24 ± 0.01R ⊙ , R 2 = 1.11 ± 0.02R ⊙ , and M 1 = 1.24 ± 0.02M ⊙ , M 2 = 0.96 ± 0.05M ⊙ and for the star ID494 as R 1 = 1.22 ± 0.02R ⊙ , R 2 = 0.81 ± 0.01 R ⊙ , and M 1 = 1.20 ± 0.06 M ⊙ , M 2 = 0.47 ± 0.01 M ⊙ .

The first photometric, spectroscopic, and period variation studies of neglected short-period eclipsing binary V2840 Cygni are presented. High Mass Ratio Contact Binaries, especially those in the weak-contact configuration are vital while probing into the evolutionary models of CBs using stellar parameters. The photometric solutions reveal the weak-contact nature of V2840 Cygni with a high mass ratio ($\sim1.36$), motivating us to investigate the nature of such binaries. The period variation study of V2840 Cygni spanning for 15 years shows a secular period decrease at a rate of \begin{math}\sim5.5\times10^{-7}\end{math}d/yr indicating mass transfer between the components. The superimposed cyclic variation provides a basic understanding of the possible third body (\emph{P$_3$}$\sim8$ yr, \emph{m$_3$}$\sim0.51$M$_\odot$). Following the derived parameters, the evolution of the system is discussed based on Thermal Relaxation Oscillation (TRO) model. It is found that V2840 Cygni falls in a special category of HMRCBs, that validates TRO. To characterise the nature of HMRCBs, a catalog of 114 CBs with high mass ratios has been compiled along with their derived parameters from the literature. For all the HMRCBs in the study, a possible correlation between their contact configuration and observed period variations for relative log\emph{J$_{rel}$} is discussed. The spectroscopic study of V2840 Cygni provides evidence of the presence of magnetic activity in the system and the existence of ongoing mass transfer which is additionally deduced from the period variation study. The LAMOST spectra of 30 HMRCBs are collected to interpret the stellar magnetic activity in such systems.

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