Related papers: Toward Understanding the B[e] Phenomenon. VII. AS …
Stellar-mass black holes have all been discovered through X-ray emission, which arises from the accretion of gas from their binary companions (this gas is either stripped from low-mass stars or supplied as winds from massive ones). Binary…
We present the results of bispectrum speckle interferometry of the B[e] star MWC 349A obtained with the SAO 6m telescope. Our diffraction-limited J-, H-, and K-band images (resolutions 43--74 mas) suggest the star is surrounded by a…
A deep (~70%) and extended (~150 days) eclipse was seen towards the young multiple stellar system V773 Tau in 2010. We interpret it as due to the passage of a circumbinary disk around the B components moving in front of the A components.…
V746 Cas is known to be a triple system composed of a close binary with an alternatively reported period of either 25.4d or 27.8d and a third component in a 62000d orbit. The object was also reported to exhibit multiperiodic light…
We report discovery of a bright, nearby ($G = 13.8;\,\,d = 480\,\rm pc$) Sun-like star orbiting a dark object. We identified the system as a black hole candidate via its astrometric orbital solution from the Gaia mission. Radial velocities…
The Galactic B[e] supergiant MWC 137 is surrounded by a large-scale optical nebula. To shed light on the physical conditions and kinematics of the nebula, we analyze the optical forbidden emission lines [NII] 6548,6583 and [SII] 6716,6731…
Details of simultaneous photometric and spectroscopic observations of the optical counterpart of the `supersoft' X-ray source 1E 0035.4-7230 (SMC 13) are presented. Although the spectrum is dominated by emission lines of He II, the Balmer…
We present the binary model and the eclipse timing variations of the eclipsing binary RR Cae, which consists of a white dwarf eclipsed by an M-type dwarf companion. The multi-wavelength optical photometry from the Transiting Exoplanet…
All stellar mass black holes have hitherto been identified by X-rays emitted by gas that is accreting onto the black hole from a companion star. These systems are all binaries with black holes below 30 M$_{\odot}$$^{1-4}$. Theory predicts,…
We report the results of a long-term spectroscopic monitoring of the A-type supergiant with the B[e] phenomenon 3 Pup = HD 62623. We confirm earlier findings that it is a binary system. The orbital parameters were derived using…
gamma Cas has long been famous for its unique hard X-ray characteristics. We report herein on a 53 ks Chandra HETGS observation of this target. An inspection of our spectrum shows that it is quite atypical for a massive star, with…
Emission-line stars are typically surrounded by dense circumstellar material, often in form of rings or disc-like structures. Line emission from forbidden transitions trace a diversity of density and temperature regimes. Of particular…
We report on a recent event in which, after more than a decade of slowly fading, the visual brightness of the massive young binary Z CMa suddenly started to rise by about 1 magnitude in December 1999, followed by a rapid decline to its…
The Galactic microquasar SS\,433 is very luminous and launches oppositely-directed jets of cool hydrogen at a quarter of the speed of light. Observations of emission lines from the circumbinary disk imply a system mass exceeding 40 $…
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 a very hard task, however, which is…
Photometry and spectra of the type Ib SN 1990I are presented and analysed, covering about 400 days of evolution. The presence of optical helium lines is shown. SN 1990I seems to show higher velocities compared to a sample of type Ib events.…
In this paper we analyzed the light curve of the object KIC~3832716 observed during Kepler K1 mission. We showed that this previously known eclipsing binary is in fact quadruple system, in double eclipsing binary configuration on a long…
We studied the circumstellar environment of the B[e] star HD 45677 through the analysis of the emission lines from ionized metals. We used the statistical approach of the self absorption curve method (SAC) to derive physical parameters of…
The black hole (BH) candidate SWIFT J1753.5-0127 has remained active since the onset of its 2005 outburst. Emission lines in the optical spectrum were observed at the very beginning of the outburst, but since then the spectrum has been…
We present results of nearly six years of spectroscopic observations of the B[e] star V2028 Cyg. The presence of the cold-type absorption lines combined with a hot-type spectrum indicate the binarity of this object. Since B[e] stars are…