Context: Optical novae have recently been identified as the major class of supersoft X-ray sources in M 31 based on ROSAT and early XMM-Newton and Chandra observations. Aims: This paper reports on a search for X-ray counterparts of optical novae in M 31 based on archival Chandra HRC-I and ACIS-I as well as XMM-Newton observations of the galaxy

Context: Over the last decade a series of results have lent support to the hypothesis of the existence of a long thin bar in the Milky Way with a half-length of 4.5 kpc and a position angle of around 45°. This is apparently a very different structure from the triaxial bulge of the Galaxy. Aims: In this paper, we analyse the stellar distribution in

We have studied the optical spectra of a sample of 28 O- and early B-type stars in the Large Magellanic Cloud, 22 of which are associated with the young star forming region N11. Our observations sample the central associations of LH9 and LH10, and the surrounding regions. Stellar parameters are determined using an automated fitting method (Mokiem

We present an analysis of high-resolution FLAMES spectra of approximately 50 early B-type stars in three young clusters at different metallicities, NGC 6611 in the Galaxy, N 11 in the Large Magellanic Cloud (LMC) and NGC 346 in the Small Magellanic Cloud (SMC). Using the tlusty non-LTE model atmospheres code, atmospheric parameters and photospheric

We present the K-correction for emission lines formed on the irradiated face of the companion stars in X-ray binaries. We compute this K-correction in a general approach as function of the mass ratio and the disc flaring angle. Our results combined with the detection of high energy emission lines arising from the donor star (e. g. Steeghs & Casares

We present Hα and [OIII] (5007 Å) images of the nebula powered by the jet of the black hole candidate and microquasar Cygnus X-1, observed with the 2.5-m Isaac Newton Telescope (INT). The ring-like structure is luminous in [OIII] and there exists a thin outer shell with a high [OIII]/Hα flux ratio. This outer shell probably originates in the