Related papers: X-rays from the oxygen-type Wolf-Rayet binary WR30…
There is growing evidence that a treatment of binarity amongst OB stars is essential for a full theory of stellar evolution. However the binary properties of massive stars - frequency, mass ratio and orbital separation - are still poorly…
Four XMM-Newton observations of the core of M31, spaced at 6 month intervals, show that the brightest point X-ray source, RX J0042.6+4115, has a 0.4-10 keV luminosity of ~5 10^38 erg/s, and exhibits significant variability in intensity and…
Two different models have been put forward to explain the origin of the X-ray emission of the unusual X-ray source 1E 1024.0-5732/Wack 2134: a high-mass X-ray binary system (HMXB) and a colliding wind binary (CWB). We present new optical…
Recent observations have led to the discovery of numerous optically selected binaries containing an undetected component with mass consistent with a compact object (neutron star or white dwarf). Using the the Neil Gehrels Swift Observatory…
Cyg OB2 #8a is a massive O-type binary displaying strong non-thermal radio emission. Owing to the compactness of this binary, emission of non-thermal X-ray photons via inverse Compton scattering is expected. We first revised the orbital…
We investigated the long-term behaviour in X-rays of the colliding wind binary WR 25, using archival data obtained with Suzaku, Swift, XMM-Newton, and NuSTAR spanning over ~16 years. Our analysis reveals phase-locked variations repeating…
BAT99-129 is a massive eclipsing binary system in the Large Magellanic Cloud (LMC) which consists of WN3(h) and O5V components. A broad-band MACHO light curve of the system is studied in the present paper. A dense and extended atmosphere of…
Wolf-Rayet stars embody the final stable phase of the most massive stars immediately before their evolution is terminated in a supernova explosion. They are responsible for some of the most extreme and energetic phenomena in stellar…
S 308 is an X-ray emitting bubble that surrounds the Wolf-Rayet star WR6. The structure shines in the optical as well and is thus known as the Dolphin Nebula. Due to its large angular extent, it has been covered at only 90% with past…
The X-ray emission of the O+O binary HD166734 was monitored using Swift and XMM-Newton observatories, leading to the discovery of phase-locked variations. The presence of an f line in the He-like triplets further supports a wind-wind…
We present spectroscopic analysis of the luminous X-ray source Melnick 33Na (Mk 33Na, HSH95 16) in the LMC 30 Doradus region (Tarantula Nebula), utilising new time-series VLT/UVES spectroscopy. We confirm Mk 33Na as a double-lined O-type…
Most population I Wolf-Rayet (WR) stars are the He-rich descendants of the most massive stars (M_i = 25 - 100 M_sun). Evidence has been accumulating over the years that among all pop I WR stars, those of the relatively cool, N-rich subtype…
Recent optical and IR studies have revealed that the heavily-reddened starburst cluster Westerlund 1 (Wd 1) contains at least 22 Wolf-Rayet (WR) stars, comprising the richest WR population of any galactic cluster. We present results of a…
Low-mass X-ray binaries are binary systems composed of a compact object and a low-mass star. Recently, a new class of these systems, known as symbiotic $X$-ray binaries (with a neutron star with a M-type giant companion), has been…
We present the discovery of OB type absorption lines superimposed to the emission line spectrum, and the first double-lined orbital elements for the massive Wolf-Rayet binary HDE 318016 (=WR 98), a spectroscopic binary in a circular orbit…
In this paper we analyse five observations of the BL Lac object AO 0235+16 performed with the Chandra and XMM-Newton satellites during the years 2000-2005. In the February 2002 observation the source is found in a bright state and presents…
Nearly all types of massive stars with radiatively driven stellar winds are X-ray sources that can be observed by the presently operating powerful X-ray telescopes. In this review I briefly address recent advances in our understanding of…
We review the X-ray observations of hot subdwarf stars. While no X-ray emission has been detected yet from binaries containing B-type subdwarfs, interesting results have been obtained in the case of the two luminous O-type subdwarfs HD…
WR~102-1 was detected by Suzaku as a conspicuous point source in the 6.7 keV intensity map of the central region of the Milky Way. The source was suggested as a possible Wolf-Rayet binary based on its X-ray and infrared spectral…
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…