In this study, we present long term photometric variations of the close binary system astrobj{GO Cyg}. Modelling of the system shows that the primary is filling Roche lobe and the secondary of the system is almost filling its Roche lobe. The physical
parameters of the system are $M_1 = 3.0pm0.2 M_{odot}$, $M_2 = 1.3 pm 0.1 M_{odot}$, $R_1 = 2.50pm 0.12 R_{odot}$, $R_2 = 1.75 pm 0.09 R_{odot}$, $L_1 = 64pm 9 L_{odot}$, $L_2 = 4.9 pm 0.7 L_{odot}$, and $a = 5.5 pm 0.3 R_{odot}$. Our results show that astrobj{GO Cyg} is the most massive system near contact binary (NCB). Analysis of times of the minima shows a sinusoidal variation with a period of $92.3pm0.5$ years due to a third body whose mass is less than 2.3$M_{odot}$. Finally a period variation rate of $-1.4times10^{-9}$ d/yr has been determined using all available light curves.
In this study, we present photometric and spectroscopic variations of the extremely small mass ratio ($qsimeq 0.1$) late-type contact binary system astrobj{V1191 Cyg}. The parameters for the hot and cooler companions have been determined as $M_textrm
{h}$ = 0.13 (1) $M_{odot}$, $M_textrm{c}$ = 1.29 (8) $M_{odot}$, $R_textrm{h}$ = 0.52 (15) $R_{odot}$, $R_textrm{c}$ = 1.31 (18) $R_{odot}$, $L_textrm{h}$ = 0.46 (25) $L_{odot}$, $L_textrm{c}$ = 2.71 (80) $L_{odot}$, the separation of the components is $a$= 2.20(8) $R_{odot}$ and the distance of the system is estimated as 278(31) pc. Analyses of the times of minima indicates a period increase of $frac{dP}{dt}=1.3(1)times 10^{-6}$ days/yr that reveals a very high mass transfer rate of $frac{dM}{dt}=2.0(4)times 10^{-7}$$M_{odot}$/yr from the less massive component to the more massive one. New observations show that the depths of the minima of the light curve have been interchanged.
In this study we determined precise orbital and physical parameters of the very short period low-mass contact binary system CC Com. The parameters are obtained by analysis of the new CCD data with the archival spectroscopic data. The physical paramet
ers of the components derived as $M_textrm{c}$ = 0.717(14) $M_{odot}$, $M_textrm{h}$ = 0.378(8) $M_{odot}$, $R_textrm{c}$ = 0.708(12) $R_{odot}$, $R_textrm{h}$ = 0.530(10) $R_{odot}$, $L_textrm{c}$ = 0.138(12) $L_{odot}$, $L_textrm{h}$ = 0.085(7) $L_{odot}$, and the distance of the system is estimated as 64(4) pc. The times of minima obtained in this study and with those published before enable us to calculate the mass transfer rate between the components which is $1.6times10^{-8}$ M$_{odot}$yr$^{-1}$. Finally, we discuss the possible evolutionary scenario of CC Com.
We present a ground based photometry of the low-temperature contact binary BB Peg. We collected all times of mid-eclipses available in literature and combined them with those obtained in this study. Analyses of the data indicate a period increase of
3.0(1) x 10^{-8} days/yr. This period increase of BB Peg can be interpreted in terms of the mass transfer 2.4 x 10^{-8} Ms yr^{-1} from the less massive to the more massive component. The physical parameters have been determined as Mc = 1.42 Ms, Mh = 0.53 Ms, Rc = 1.29 Rs, Rh = 0.83 Rs, Lc = 1.86 Ls, and Lh = 0.94 Ls through simultaneous solution of light and of the radial velocity curves. The orbital parameters of the third body, that orbits the contact system in an eccentric orbit, were obtained from the period variation analysis. The system is compared to the similar binaries in the Hertzsprung-Russell and Mass-Radius diagram.
