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Eclipsing systems of massive stars allow one to explore the properties of their components in great detail. We perform a multi-wavelength, non-LTE analysis of the three components of the massive multiple system $\delta$ Ori A, focusing on…
We report high-precision observations of the linear polarization of the F1$\,$III star $\theta$ Scorpii. The polarization has a wavelength dependence of the form expected for a rapid rotator, but with an amplitude several times larger than…
We present radio observations at three frequencies and contemporaneous optical monitoring of the peculiar BL Lac object AO 0235+164. During a three-week campaign with the VLA we observed intraday variability in this source and found a…
Gaseous metal discs around single white dwarfs have been discovered recently. They are thought to develop from disrupted planetary bodies. Spectroscopic analyses will allow us to study the composition of extrasolar planetary material. We…
Radial velocity measurements and simple sine-curve fits to the orbital velocity variations are presented for the second set of ten contact binary systems. Eight systems are of the A-type: AH Aur, CK Boo, DK Cyg, UZ Leo, XZ Leo, V839 Oph, GR…
The stellar population of the 30 Doradus star-forming region in the Large Magellanic Cloud contains a subset of apparently single, rapidly rotating O-type stars. The physical processes leading to the formation of this cohort are currently…
The luminosity function for contact binary stars of the W~UMa-type is evaluated on the basis of the ASAS photometric project covering all stars south of delta= +28 within a magnitude range 8<V<13. Lack of colour indices enforced a…
Images of the Kuiper belt object (126719) 2002 CC249 obtained in 2016 and 2017 using the 6.5m Magellan-Baade Telescope and the 4.3m Discovery Channel Telescope are presented. A lightcurve with a periodicity of 11.87+/-0.01 h and a…
The new discovered short-period close binary star, XY LMi, was monitored photometrically since 2006. It is shown that the light curves are typical EW-type and show complete eclipses with an eclipse duration of about 80 minutes. By analyzing…
We have carried out an analysis of about 160 eclipse timings spanning over 30 years of the Hyades eclipsing binary V471 Tauri that shows a long-term quasi-sinusoidal modulation of its observed eclipse arrival times. The O-Cs have been…
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…
In this study, we determined the physical parameters of W UMa type contact binaries and its stability of mass transfer with different stellar mass ranges over a broad space by applying the basic dynamical evolution equations of the W UMa…
Reliable determination of the basic physical properties of hot emission-line binaries with Roche-lobe filling secondaries is important for developing the theory of mass exchange in binaries. It is not easy, however, due to the presence of…
We present a photometric analysis of the TESS light curve of contact binary system DY Cet and the behavior of its orbital period variation. The light curve and published radial velocity data analysis was performed using Wilson-Devinney…
We present an analysis of a new, detached, double-lined eclipsing binary system with K7 Ve components, discovered as part of the University of New South Wales Extrasolar Planet Search. The object is significant in that only 6 other binary…
The secondary photometric standard star #79 for the FS Aur field (Henden & Honeycutt 1997) designated as [HH97] FS Aur-79 (GSC 1874 399) is a short period (0.2508 days) eclipsing binary whose light curve is a combination of the $\beta$ Lyr…
In this study, we conducted a comprehensive analysis of the SX Phoenicis (SX Phe) type star CY Aquarii (CY Aqr). Our investigation included a detailed $O-C$ analysis based on a 90-year observational dataset, augmented by 1,367 newly…
We present an eccentric, short-period brown dwarf candidate orbiting the active, slightly evolved subgiant star TYC 2087-00255-1, which has effective temperature T_eff = 5903+/-42 K, surface gravity log (g) = 4.07+/-0.16 (cgs), and…
We present the first high-resolution spectra for the eclipsing binary V404 Lyr showing $\gamma$ Dor pulsations, which we use to study its absolute properties. By fitting models to the disentangling spectrum of the primary star, we found…
We report the confirmation of the binary nature of the nearby, very low-mass system NLTT 33370 with adaptive optics imaging and present resolved near-infrared photometry and integrated light optical and near-infrared spectroscopy to…