Related papers: A Binary Orbit for the Massive, Evolved Star HDE 3…
Near infrared spectroscopy and photometry of the Wolf-Rayet Star WR 143 (HD 195177) were obtained in the $JHK$ photometric bands. High resolution spectra observed in the J and H bands exhibit narrow 1.083-micron He I line and the H I Pa…
WR 31a (Hen 3-519) is likely a post-luminous blue variable (LBV) star that is evolving to become a classical Wolf-Rayet star. Multicolor (UBVR) photopolarimetric observations of WR 31a were obtained over nine nights in early 2007. The…
As part of a multi-year survey for Wolf-Rayet stars in the Magellanic Clouds, we have discovered a new type of Wolf-Rayet star with both strong emission and absorption. While one might initially classify these stars as WN3+O3V binaries…
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…
The B[e]/K binary system MWC 623 was reinvestigated using new spectroscopic observations. The absorption lines of the K and the B star do not exhibit any significant radial velocity variations over a time interval of 14 years. The spectral…
About 10% of all stars exhibit absorption lines of ultra-high excited (UHE) metals (e.g. OVIII) in their optical spectra when entering the white dwarf cooling sequence. The recent discovery of a both spectroscopic and photometric variable…
HD 326823 is a peculiar emission line object. In the literature it was considered as a pre-WN candidate. Based mainly on high resolution data, obtained with the FEROS spectrograph, we made an atlas covering 3800-9200A region. This atlas…
The B-emission line stars are rapid rotators that were probably spun up by mass and angular momentum accretion through mass transfer in an interacting binary. Mass transfer will strip the donor star of its envelope to create a small and hot…
New spectroscopic observations of the halo hyper-velocity star candidate SDSS J121150.27+143716.2 ($V=17.92$ mag) revealed a cool companion to the hot subdwarf primary. The components have a very similar radial velocity and their absolute…
The origin of rapid rotation in massive stars remains debated, although binary interactions are now often advocated as a cause. However, the broad and shallow lines in the spectra of fast rotators make direct detection of binarity…
We study the O-type star HD 161853, which has been noted as a probable double-lined spectroscopic binary system. We secured high-resolution spectra of HD 161853 during the past nine years. We separated the two components in the system and…
From radial velocities determined in high signal-to-noise digital spectra, we report the discovery that the brightest component of the binary system HD 150136 is of spectral type O3. We also present the first double-lined orbital solution…
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…
The recent discovery of a ~9.5-d period in the X-ray lightcurve of the massive X-ray binary 4U2206+54 has opened the possibility that it is a Be/X-ray binary with an unusually close orbit, which, together with its low intrinsic luminosity,…
Classical Wolf-Rayet stars are descendants of massive OB-type stars that have lost their hydrogen-rich envelopes, and are in the final stages of stellar evolution, possibly exploding as type Ib/c supernovae. It is understood that the…
Most (or possibly all) massive stars reside in multiple systems. From stellar evolution models, numerous systems with an OB star coupled to a black hole would be expected to exist. There have been several claimed detections of such pairs in…
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…
The similarity in physical conditions in winds of low-mass post-asymptotic giant branch stars and evolved massive stars leads to the appearance of an interesting phenomenon of spectral mimicry. Due to that the discovery of every new star…
The emission-line Be star HD 215227 lies within the positional error circle of the newly identified gamma-ray source AGL J2241+4454. We present new blue spectra of the star, and we point out the morphological and variability similarities to…
We report on the discovery of the shortest period binary comprising a hot subdwarf star (CD-30 11223, GALEX J1411-3053) and a massive unseen companion. Photometric data from the All Sky Automated Survey show ellipsoidal variations of the…