Related papers: The energy transfer and its effects on the seconda…
We use extensive model grids to estimate the global parameters of four partially-eclipsing W UMa contact binaries near the period cutoff. All four systems consist of K-type main sequence primaries and M-type secondaries that appear…
A re-examination of high-resolution spectral monitoring of the W UMa-type binaries AW UMa and Epsilon CrA casts doubt on the widely utilized Lucy (1968a, 1968b) model of contact binaries. The detection of the very faint profile of the…
We present the multi-band photometric and low-resolution spectroscopic analysis of four W Ursae Majoris eclipsing binaries (EWs) - J080510.1+141528 (hereinafter as J0805a), J080516.3+143138 (hereinafter as J0805b), J143358.7+053953…
Contact binaries are close binary systems in which both components fill their inner Roche lobes so that the stars are in direct contact and in potential mass and energy exchange. The most common such systems of low-mass are the so-called W…
In radiative layers of rotating stars the luminosity carried by circulation currents through a surface of constant entropy (circulation luminosity) is shown to be positive. The corresponding decrease in the temperature gradient is important…
The first V Rc Ic bands light curves of MQ UMa are presented and analyzed using the Wilson-Devinney (W-D) program. It is discovered that MQ UMa is an A-subtype contact binary with a high fill-out (f=82 %) and a low mass ratio (q = 0:195),…
Various scenarios of contact binary evolution have been proposed in the past, giving hints of (sometimes contradictory) evolutionary sequence connecting A-type and W-type systems. As the components of close detached binaries approach each…
The mass ratio $q$ of a contact binary star evolves due to mass transfer, magnetic braking, and thermal relaxation oscillations to small values until it crosses a critical threshold $q_\text{min}$. When that happens, the binary undergoes…
We present a phase-resolved spectroscopic study of the secondary star in the cataclysmic variable U Gem. We use our data to measure the radial velocity semi-amplitude, systemic velocity and rotational velocity of the secondary star.…
Multi-band (B, V and R) photometric and spectroscopic observations of six poorly studied contact binaries carried out at the Western Sydney University and Las Cumbres Observatory were analysed using a recent version of the Wilson-Devenney…
We present two-dimensional (radial velocity, orbital phase) spectroscopic results for the very low mass-ratio close binary AW UMa which strongly indicate that the spectroscopic mass ratio (q_sp = 0.10) does not agree with the…
We characterize ${\sim} 71,200$ W UMa type (EW) contact binaries, including ${\sim} 12,600$ new discoveries, using ASAS-SN $V$-band all-sky light curves along with archival data from Gaia, 2MASS, AllWISE, LAMOST, GALAH, RAVE, and APOGEE.…
We obtained multi-colour light curves of HH Boo. We analysed the orbital period variation of the system. The analysis indicated that there is possible mass transfer from the second component to the primary or mass loss with -5.04x10-7 Msun…
We present a comprehensive photometric light curve and orbital period analysis of the W UMa-type contact binary EM Tuc. The O-C analysis constructed from all available eclipse timings exhibits a clear upward parabolic trend, indicating a…
Contact binaries are very short-period systems that are continuously interacting by transferring mass and energy. Obtaining large, statistical samples of contact binaries from photometric surveys can put valuable constraints on the various…
ZZ UMa is a detached eclipsing binary with an orbital period of 2.299 d that shows total eclipses and starspot activity. We used five sectors of light curves from the Transiting Exoplanet Survey Satellite (TESS) and two published sets of…
This study presents new, high-quality, optical photometric observations of three W UMa type contact binaries. The analysis of the corresponding light curves is made using Djurasevic's inverse problem method. To explain the light curve…
Several dozen binary ultracool and brown dwarf systems have been identified to date. These systems represent valuable probes of star and planet formation at the lowest mass scales. To date, the study of these ultracool binaries has been…
Results are presented on component masses and system angular momenta for over a hundred low-temperature contact binaries. It is found that the secondary components in close binary systems are very similar in mass. Our observational evidence…
Among massive stars, binary interaction is the rule rather than the exception. The closest binaries, those with periods of less than about 10 days, undergo mass transfer during core-hydrogen burning, with many of them experiencing a…