Related papers: Wind clumping and the wind-wind collision zone in …

In this work the thermal emission over cm to sub-mm wavelengths from the winds in short-period O+O-star binaries is investigated (potential non-thermal emission is presently ignored). The calculations are based on three-dimensional…

Recently, a powerful magnetic field was discovered in the hot helium star classified as a quasi-Wolf-Rayet star of ~2Msun, member of the HD45166 system. Upon its explosion as a core-collapse supernova, it is expected to produce a strongly…

In the colliding wind region of early-type binaries, electrons can be accelerated up to relativistic energies displaying power-law spectra, as demonstrated by the detection of non-thermal radio emission from several WR+OB systems. The…

WR21 and WR31 are two WR+O binaries with short periods, quite similar to the case of V444 Cyg. The XMM-Newton observatory has monitored these two objects and clearly revealed phase-locked variations as expected from colliding winds. The…

Radiative transfer in a clumped winds is used to describe X-ray emission line profiles observed in the XMM-Newton RGS spectrum of the OI star Zeta Puppis. It is shown that this X-ray spectrum can be explained as originating from a…

The spectra of Wolf-Rayet (WR) stars exhibit strong, broad emission lines that originate in the wind. These winds are radiatively driven and are susceptible to hydrodynamic instabilities that result in the formation of clumps. When…

Gamma-ray binaries are systems containing a massive star and a compact object that have been detected up to TeV energies. The high energy emission could result from particle acceleration in the region where the stellar wind from the massive…

The X-ray emission from the massive binary WR 146R is analysed in the framework of the colliding stellar wind (CSW) picture. The theoretical CSW model spectra match well the shape of the observed X-ray spectrum of WR 146R but they…

Transient X-ray obscuration in Seyfert 1 galaxies is thought to arise from clumpy accretion-disk winds near the broad-line region (BLR), but the wind structure and its short-timescale variability are difficult to measure because…

We present results from simultaneous observations of the high-mass X-ray binary system Cygnus X-1 / HDE 226868 with Suzaku, Chandra-HETGS, XMM-Newton, RXTE, INTEGRAL, and Swift in 2008 April. Performed shortly after orbital phase 0, when…

We report the discovery of weak yet hard X-ray emission from the Wolf-Rayet (WR) star WR142 with the XMM-Newton X-ray telescope. Being of spectral subtype WO2, WR142 is a massive star in a very advanced evolutionary stage, short before its…

Colliding winds of massive binaries have long been considered as potential sites of non-thermal high-energy photon production. This is motivated by the detection of non-thermal spectra in the radio band, as well as by correlation studies of…

[Abridged] Clumping in the radiation-driven winds of hot, massive stars affects the derivation of synthetic observables across the electromagnetic spectrum. We implement a formalism for treating wind clumping - in particular the…

The clumping of massive star winds is an established paradigm, which is confirmed by multiple lines of evidence and is supported by stellar wind theory. We use the results from time-dependent hydrodynamical models of the instability in the…

Quantitative constraints on the wind clumping of massive stars can be obtained from the study of the hard X-ray variability of SFXTs. In these systems, a large fraction of the hard X-ray emission is emitted in the form of flares with…

Wolf-Rayet stars are known to eject winds. Thus, when a Wolf-Rayet star explodes as a supernova, a fast, $>30,000$ km/s, shock is expected to be driven through a wind. We study the signal expected from a fast supernova shock propagating…

X-ray observations of the double-binary OB-star system QZ Car (HD 93206) obtained with the Chandra X-ray Observatory over a period of roughly 2 years are presented. The orbit of systems A (O9.7 I+b2 v, PA = 21 d) and B (O8 III+o9 v, PB = 6…

We present an analysis of three Chandra High Energy Transmission Gratings observations of the black hole binary Cyg X-1/HDE 226868 at different orbital phases. The stellar wind that is powering the accretion in this system is characterized…

The dynamics of colliding wind binary systems and conditions for efficient particle acceleration therein have attracted multiple numerical studies in the recent years. These numerical models seek an explanation of the thermal and…

We have performed the near-infrared photometric monitoring observations of two TeV gamma-ray binaries with O-stars (LS 5039 and 1FGL J1018.6-5856), using IRSF/SIRIUS at SAAO, in order to study the stellar parameters and their perturbations…