Related papers: The low mass ratio contact binary system V728 Herc…

We report extensive spectroscopic and differential V-band photometric observations of the 18.4-day detached double-lined eclipsing binary LV Her (F9V), which has the highest eccentricity (e = 0.613) among the systems with well-measured…

I present results from an optical spectroscopic investigation of the binary system HD 42401 (V1388 Ori; B2.5 IV-V + B3 V). A combined analysis of V-band photometry and radial velocities indicates that the system has an orbital period of…

The multi-color photometric light curves for a contact binary AV Puppis (AV Pup) in $VR_cI_c$ bandpasses are presented, and they are analyzed by using of the 2013 version of the Wilson-Devinney (W-D) code. The solutions suggest that AV Pup…

New spectroscopic observations of the LBV/WR multiple system HD5980 in the Small Magellanic Cloud are used to address the question of the masses and evolutionary status of the two very luminous stars in the 19.3d eclipsing binary system.…

Photometric and spectroscopic studies of four long-period low mass-ratio contact binaries, V0508 And, V0844 Aur, V0699 Cep, and NSVS 6259046, are performed. V0508 And, V0844 Aur, and V0699 Cep are found to be A-type low-mass-ratio…

We present a study on low-mass contact binaries (LMCB) with orbital periods shorter than 0.3 days and total mass lower than about 1.4 solar mass. We show that such systems have a long pre-contact phase, which lasts for 8-9 Gyrs, while the…

A photometric and spectroscopic investigation is performed on five W Ursae Majoris eclipsing binaries (EWs) J015818.6+260247 (hereinafter as J0158b), J073248.4+405538 (hereinafter as J0732), J101330.8+494846 (hereinafter as J1013),…

Multi-color photometric light curves of NO Cam in $V$ $R_C$ and $I_C$ bands are obtained and analyzed simultaneously using the Wilson-Devinney (W-D) program. The solutions suggest that NO Cam is an A-subtype overcontact binary with its mass…

The cut-off mass ratio is under debate for contact binaries. In this paper, we present the investigation of two contact binaries with mass ratios close to the low mass ratio limit. It is found that the mass ratios of VSX J082700.8+462850…

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…

HD~5501, a hitherto little studied eclipsing binary with an early A-type primary, has been caught in a short-lived, astrophysically interesting phase of its binary evolution. Recent photometric and spectroscopic observations, including…

Multi-color ($B$ $V$ $R_c$ $I_c$) CCD photometric light curves of the contact binary V502 Oph are analyzed using the Wilson-Devinney (W-D) program. The solutions reveal that V502 Oph is a W-subtype contact ($f = 35.3\,\%$) binary system.…

Both high precision CCD photometric and H$alpha$ line studies are presented for an overcontact binary ASAS J082243+1927.0. The light curve exhibits a total eclipse at secondary minima along with an O'Connell effect. The light curve was…

The first photometric analysis of V811 Cep was carried out. The first complete light curves of V, R and I bands are given. The analysis was carried out by Wilson-Devinney (W-D) program, and the results show that V811 Cep is a median-contact…

In this paper, CCD photometric light curves for the short-period eclipsing binary 1SWASP J140533.33+114639.1 (hereafter J1405) in the $BVR$ bands are presented and analyzed using the 2013 version of the Wilson-Devinney (W-D) code. It is…

This study examines the period variation of the eclipsing binary system KR Cyg, a near-contact binary characterized by its short orbital period and significant stellar interactions. The precise orbital parameters of the system have been…

We present the results of the study of the contact binary system BO CVn. We have obtained physical parameters of the components based on combined analysis of new, multi-color light curves and spectroscopic mass ratio. This is the first time…

Aims: We present a new updated study of the unique quintuple system of two eclipsing binaries, V994 Her. Methods: Based on new obtained photometric observations, we analysed the period variations of the two eclipsing pairs of V994 Her.…

The photometric and spectroscopic investigations of ten contact binaries were presented for the first time. It is discovered that the mass ratios of all the ten targets are smaller than 0.15, they are extremely low mass ratio contact…

II UMa is a late F-type (F5) contact binary with a close-in tertiary and a distant visual companion. According to the four-color ($B$ $V$ $R_c$ $I_c$) light curves' solutions of II UMa, it is a high fill-out (f=$86.6\,\%$) and low mass…