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Here we present the study of FR Cnc, a young, active and spotted star. We performed analysis of ASAS-3 (The All Sky Automated Survey) data for the years 2002-2008 and amended the value of the rotational period to be 0.826518 d. The…

We present here 55 short period PCEBs containing a hot WD and a low-mass MS. Based on the photometric data from ZTF DR19, the light curves are analyzed for about 200 WDMS binaries with emission line(s) identified from SDSS or LAMOST…

Interacting transients probe mass loss in the final stages of stellar evolution; however, the geometry and timing of multi-episode mass loss remain poorly constrained. SN 2024abvb is a nearby interacting event with transitional Ibn/Icn…

We report 138 spectral observations of the H-alpha emission line of the radio- and gamma-ray-emitting Be/X-ray binary LSI+61303 obtained during the period of September 1998 -- January 2013. From measuring various H-alpha parameters, we…

We present a comprehensive photometric, spectroscopic, and polarimetric study of the intermediate polar (IP) 1RXS J080114.6-462324, using observations from the South African Astronomical Observatory (SAAO) 1.0-m and 1.9-m telescopes and the…

We present the results of optical wavelength observations of the unusual SMC eclipsing binary system HD 5980 obtained in 1999 and 2004--2005. Radial velocity curves for the erupting LBV/WR object (star A) and its close WR-like companion…

AIMS: The main goal of this work is to study possible signs of asymmetry in the bright optical transient in NGC300, with the aim of getting independent information on the explosion mechanism, the progenitor star and its circumstellar…

We present the results from a multi-wavelength study of the mixed H+He composition DAO white dwarf RE J0720-318. A detailed analysis of UV and EUV spectroscopic data with state-of-the-art non-LTE photospheric models demonstrates that the…

(Abridged) X1822-371 is the prototypical accretion disc corona X-ray source, a low-mass X-ray binary viewed at very high inclination, thereby allowing the disc structure and extended disc coronal regions to be visible. We study the…

We report our discovery of an extremely rare, low mass, quadruple-lined spectroscopic binary BD-22 5866 (=NLTT 53279, integrated spectral type = M0 V), found during an ongoing search for the youngest M dwarfs in the solar neighborhood. From…

FUSE spectra were obtained of the supersoft X-ray binary RX J0019.8+2156 (QR And) during 16 consecutive spacecraft orbits, covering the binary orbit (P=15.85 hr) with about 0.2 phase overlap. The spectrum is dominated by strong H2…

We obtained multi-epoch Very Large Telescope (VLT) optical spectroscopic data in 2011 and 2012 on the ultraluminous X-ray source (ULX) NGC 5408 X-1. We confirm that the HeII\lambda4686 line has a broad component with an average FWHM of…

We report detailed follow-up observations of the cataclysmic variable HS2331+3905, identified as an emission-line object in the Hamburg Quasar Survey. An orbital period of 81.08min is unambiguously determined from the detection of eclipses…

We address the problem where the X-ray emission lines are formed and investigate orbital dynamics using Chandra HETG observations, photoionizing calculations and numerical wind-particle simulations.The observed Si XIV (6.185 A) and S XVI…

AH Cep and CW Cep are both early B-type binaries with short orbital periods of 1.8~d and 2.7~d, respectively. All four components are B0.5V types. The binaries are also double-lined spectroscopic and eclipsing. Consequently, solutions for…

We present the first time-resolved spectroscopic study of the cataclysmic variable DW Cancri. We have determined an orbital period of 86.10 +- 0.05 min, which places the system very close to the observed minimum period of hydrogen-rich…

Results of the long-term (11 years, from 1996 to 2006) H$\alpha$ and H$\beta$ line variations of the active galactic nucleus of NGC 4151 are presented. High quality spectra (S/N>50 and R~8A) of H$\alpha$ and H$\beta$ were investigated. We…

The nearby galaxy NGC 300 is hosting two luminous transient supersoft X-ray sources with bolometric luminosities above 3x10^38 erg/s, assuming simple black-body spectra with temperatures around 60-70 eV. For one of these, SSS1, a periodic…

We present the results of fast temporal optical spectroscopy and photometry of the AM Her type system BY Cam obtained in February 1990 and March 1991. Emission line profiles show a complex structure and are strongly variable. The radial…

We present the discovery of CoRoT 223992193, a double-lined, detached eclipsing binary, comprising two pre-main sequence M dwarfs, discovered by the CoRoT space mission during a 23-day observation of the 3 Myr old NGC 2264 star-forming…