Related papers: HD3191, the high-mass X-ray binary that wasn't the…
Early-type magnetic stars are rarely found in close binary systems. No such objects were known in eclipsing binaries prior to this study. Here we investigated the eclipsing, spectroscopic double-lined binary HD66051, which exhibits…
Cygnus X-1 is a binary star system that is comprised of a black hole and a massive giant companion star in a tight orbit. Building on our accurate distance measurement reported in the preceding paper, we first determine the radius of the…
We report the discovery of a variable optical and X-ray source within the error ellipse of the previously unassociated Fermi Large Area Telescope $\gamma$-ray source 4FGL J0407.7--5702. A 22 ksec observation from XMM-Newton/EPIC shows an…
IGR J16320-4751 is a highly obscured HMXB source containing a very slow neutron star ($P_{spin}\sim1300$ sec) orbiting its supergiant companion star with a period of $\sim$9 days. It shows high column density ($N_{H}\sim2-5\times10^{23}$…
We present the results of a long-term monitoring campaign of the H\alpha line in a sample of bright OB-supergiants (O7.5-B9) that aims at detecting rotationally modulated changes potentially related to the existence of large-scale wind…
4FGL J1405.1-6119 is a high-mass $\gamma$-ray emitting binary that has been studied at several wavelengths. The nature of this type of binary is still under debate, with three possible scenarios usually invoked to explain the origin of the…
We present the analysis of an extensive set of high resolution spectroscopic observations of HD93161, a visual binary with a separation of 2 arcsec. HD93161 A is a spectroscopic binary, with both components clearly detected throughout the…
Context. HD 85567 is an enigmatic object exhibiting the B[e] phenomenon, i.e. an infrared excess and forbidden emission lines in the optical. The object's evolutionary status is uncertain and there are conflicting claims that it is either a…
We report on the follow-up XMM-Newton observation of the planet-hosting star HD 189733 we obtained in April 2011. We observe a flare just after the secondary transit of the hot Jupiter. This event shares the same phase and many of the…
Binary systems consisting of an early type star and a black hole (BH) are crucial for understanding various astrophysical phenomena, particularly the origins of detected gravitational wave sources. Be binary systems are expected to…
We present multifrequency radio continuum as well as HI observations of the superwind galaxy NGC1482, with both the GMRT and the VLA. This galaxy has a remarkable hourglass-shaped optical emission line outflow as well as bi-polar soft X-ray…
We investigate the nature of the unidentified very-high-energy (VHE) gamma-ray object, HESS J1832-093, in a multi-wavelength context. Based on X-ray variability and spectral index ($\Gamma_X\sim\,1.5$), and its broad-band spectrum (which…
The young, compact, very high surface brightness but low excitation planetary nebula (PN) BD+303639 is one of the very few PNe that have been reported to exhibit the 21cm HI emission line. As part of a long-term programme to search for…
We have identified the optical counterpart of the ULX source P13 in the nearby spiral galaxy NGC 7793. The object is a V ~ 20.5 mag star, ten times brighter than any other established counterpart of a ULX in nearby galaxies. Medium…
Infrared photometry and spectroscopy covering a time span of a quarter century are presented for HD 31648 (MWC 480) and HD 163296 (MWC 275). Both are isolated Herbig Ae stars that exhibit signs of active accretion, including driving bipolar…
HD49798 / RXJ0648.0-4418 is the only confirmed X-ray binary in which the mass donor is a hot subdwarf star of O spectral type and, most likely, it contains a massive white dwarf (1.28$\pm$0.05 M$_{\rm SUN}$) with a very fast spin period of…
The fate of massive stars above 20M$_{\odot}$ remains uncertain. Debate persists about whether they die as supernovae (SNe), or if they collapse directly into black holes (BHs) with little or no optical outburst -- so-called ``failed…
The gamma-ray binary LS I +61 303 is one of the brightest Fermi sources, with orbitally modulated emission across the electromagnetic spectrum. Here we present H-alpha spectra of LS I +61 303 that exhibit a dramatic emission burst shortly…
We report on the discovery of a fourth component in the HD 221356 star system, previously known to be formed by an F8V, slightly metal-poor primary ([Fe/H]=-0.26), and a distant M8V+L3V pair. In our ongoing common proper motion search based…
We present a quantitative spectral analysis of the extreme nitrogen-enhanced supergiant HD 93840 (BN1 Ib) at an intermediate galactic latitude. Based on an optical high-resolution spectrum and complementary ultraviolet and infrared…