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Aims. HD166734 is an eccentric eclipsing binary system composed of two supergiant O-type stars, orbiting with a 34.5-day period. In this rare configuration for such stars, the two objects mainly evolve independently, following single-star…
We present new, high-quality multicolor observations of four recently discovered contact binaries: 1SWASP J064501.21+342154.9, 1SWASP J155822.10-025604.8, 1SWASP J212808.86+151622.0, and UCAC4 436-062932, and analyze their light curves to…
XTE J1710-281 is a transient eclipsing binary system with a period close to 3.28 hours, hosting a neutron star. The average eclipse duration is 420 seconds, and eclipse arrival times reported in the literature span from 1999 to 2017. A…
O-stars are known to experience a wide range of variability mechanisms originating at both their surface and their near-core regions. Characterization and understanding of this variability and its potential causes are integral for…
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…
An accident of misidentification has brought to light the interesting system HD 191588, a new RS CVn-type spectroscopic binary. A radial-velocity study of the primary star, the only seen component, carried out at the Observatoire de…
The archival spectrum of SDSSJ212531.92-010745.9 shows not only the typical signature of a PG1159 star, but also indicates the presence of a companion. Our aim was the proof of the binary nature ofthis object and the determination of its…
V0842 Cep is a W UMa-type binary star that has been neglected since its discovery. We analysed the VR$_c$I$_c$ light curves, obtained by the 1 m telescope at the Weihai Observatory of Shandong University, using the Wilson-Devinney code.…
We present modeling of the long-term optical light curve and radial velocity curve of the binary stellar system CXOGBS J175553.2-281633, first detected in X-rays in the \textit{Chandra} Galactic Bulge Survey. We analyzed 7 years of optical…
We report the discovery of 1RXH J082623.6-505741, a 10.4 hr orbital period compact binary. Modeling extensive optical photometry and spectroscopy reveals a $\sim 0.4 M_{\odot}$ K-type secondary transferring mass through a low-state…
The first multicolor observations, and light curve solutions, of the eclipsing binary systems V1009~Per and CRTS~J031642.2+332639 are presented. Using the 2005 version of the Wilson-Devinney code, both systems are found to be W UMa contact…
The properties of the early-type binary Cyg OB2 #5 have been debated for many years and spectroscopic and photometric investigations yielded conflicting results. We have attempted to constrain the physical properties of the binary by…
We present here the results of astrometric, photometric and spectroscopic observations leading to the determination of the orbit and dynamical masses of the binary L dwarf 2MASSW J0746425+2000321. High angular resolution observations spread…
A photometric solution of an A-type W UMa binary, GSC 0763-0572 is examined with a revised orbital period. The overcontact degree is found to be $f$ = 40.66%, with a low mass ratio of $q$ = 0.2554. The result demonstrates an unambiguous…
We conducted spectroscopic and photometric observations of the optical counterpart of the X-ray transient RX J0117.6-7330 in the Small Magellanic Cloud, during a quiescent state. The primary star is identified as a B0.5 IIIe, with mass M =…
We present the first orbital elements for the massive close binary, HD 101131, one of the brightest objects in the young, open cluster, IC 2944. This system is a double-lined spectroscopic binary in an elliptical orbit with a period of…
We report the detection of eclipses in GJ 3236, a bright (I = 11.6) very low mass binary system with an orbital period of 0.77 days. Analysis of light- and radial velocity curves of the system yielded component masses of 0.38 +/- 0.02 and…
The two objects 1SWASP J150822.80-054236.9 and 1SWASP J160156.04+202821.6 were initially detected from their SuperWASP archived light curves as candidate eclipsing binaries with periods close to the short-period cut-off of the orbital…
We present new photometric and spectroscopic observations for 2M 1533+3759 (= NSVS 07826147). It has an orbital period of 0.16177042 day, significantly longer than the 2.3--3.0 hour periods of the other known eclipsing sdB+dM systems.…
Aims. We present new photometry of the faint and poorly studied cataclysmic variable SDSS J152419.33+220920.0, analyze its light curve and provide an accurate ephemeris for this system. Methods. Time-resolved CCD differential photometry was…