Related papers: $\eta$ Carinae: particle acceleration and multi-me…
We use recent observations of the He I $\lambda10830 \AA$ absorption line and 3D hydrodynamical numerical simulations of the winds collision, to strengthen the case for an orientation of the semimajor axis of the massive binary system Eta…
Aims: Non-thermal radio emission associated with massive stars is believed to arise from a wind-wind collision in a binary system. However, the evidence of binarity is still lacking in some cases, notably Cyg OB2 #9 Methods: For several…
WR 20a is the most massive close-in binary known in our Galaxy. It is composed of two $\approx$80 M$_\odot$ Wolf-Rayet stars with a short period of $\approx$3.7 days in the open cluster Westerlund 2. As such, WR 20a presents us with a…
2D axis-symmetric hydrodynamical simulations are presented which explore the interaction of stellar and disk winds with surrounding infalling cloud material. The star, and its accompanying disk, blow winds inside a cavity cleared out by an…
We present XMM-Newton observations of the luminous star Eta Carinae, including a high resolution soft X-ray spectrum of the surrounding nebula obtained with the Reflection Grating Spectrometer. The EPIC image of the field around Eta Car…
Wolf-Rayet stars represent one of the final stages of massive stellar evolution. Relatively little is known about this short-lived phase and we currently lack reliable mass, distance, and binarity determinations for a representative sample.…
X-ray emission from the supermassive star Eta Carinae (\ec) originates from hot shocked gas produced by current stellar mass loss as well as ejecta from prior eruptive events. Absorption of this emission by cool material allows the…
We present new radial velocity (RV) measurements of old (horizontal branch) and intermediate-age (red clump) stellar tracers in the Carina dwarf spheroidal. They are based on more than 2,200 low-resolution spectra collected with VIMOS at…
Wolf-Rayet (WR) stars are evolved massive stars, presumably on their way to becoming supernova. They are characterized by high luminosities and fast and dense stellar winds. We have detected signs of a radio continuum pinwheel associated…
Massive WR+O star systems produce high-temperature, shock-heated plasma where the wind of the WR star and that of its binary companion collide - the wind-collision region (WCR). The WCR is a source of thermal (e.g. hard X-rays) and…
It is clearly established that the Sun has an 11-year cycle that is caused by its internal magnetic field. This cycle is also observed in a sample of M dwarfs. In the framework of exoplanet detection or atmospheric characterisation of…
INTEGRAL tripled the number of super-giant high-mass X-ray binaries (sgHMXB) known in the Galaxy by revealing absorbed and fast transient (SFXT) systems. Quantitative constraints on the wind clumping of massive stars can be obtained from…
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…
$\eta$ Car is a massive, eccentric binary with a rich observational history. We obtained the first high-cadence, high-precision light curves with the BRITE-Constellation nanosatellites over 6 months in 2016 and 6 months in 2017. The light…
A detailed analysis of more than 800 electronic high-resolution spectra of gamma Cas, which were obtained during a time interval of over 6000 days (16.84 yrs) at several observatories, documents the smooth variations in the density and/or…
The dense wind environment (or circumstellar medium) may be ubiquitous for the regular Type II supernovae (SNe) before the explosion, the interaction of which with the SN ejecta could result in a wind breakout event. The shock generated by…
We present a detailed analysis of the extended structure detected around the young and close-by Herbig Ae/Be star RCrA. This is a young triple system with an intermediate mass central binary whose separation is of the order of a few tens of…
The long-period, highly eccentric O-star binary 9 Sgr, known for its non-thermal radio emission and its relatively bright X-ray emission, went through its periastron in 2013. Such an event can be used to observationally test the predictions…
Major stellar-wind emission features in the spectrum of Eta Car have recently decreased by factors of order 2 relative to the continuum. This is unprecedented in the modern observational record. The simplest, but unproven, explanation is a…
We propose that the decline in the near-IR flux from the massive binary system Eta Carinae during the spectroscopic event might be explained by accreted mass that absorbs the radiation from the secondary star, and by that reduces the…