We have obtained broad-band optical spectra of a sample of 15 low-mass X-ray binaries (LMXBs) in the range 4000-9000A and fitted them with combinations of standard accretion disc models plus secondary star templates. For the sample of LMXBs in which we determine the power-law indices of the accretion disc flux distribution, we can explain the

We present the first optical observations of the soft X-ray transient Nova Vela 1993, taken during quiescence in 1995 and 1996. From the R-band photometry with a mean magnitude of 20.6, we find an orbital, ellipsoidal modulation with an amplitude of 0.23 mag at a period of 6.86+/-0.12 h. The optical spectra show only broad double-peaked Hα emission

We present with outstanding detail an extragalactic perspective of an extended stellar tidal stream wrapping around the edge-on, spiral galaxy NGC 5907. Our deep images reveal for the first time a large scale complex of arcing loops that is an excellent example of how a low-mass satellite accretion can produce a interweaved, rosette-like structure

Spectral synthesis calculations in stellar (magnetized) atmospheres are based on the solution of the radiative transfer equation (RTE) for polarized light. The thermodynamic and magnetic properties of the atmospheres, along with the radiation field, completely specify the basic ingredients of the RTE, after which numerical methods have to be

We have made B, V, and I-band observations of satellite galaxies which lie around isolated disk galaxies, using the satellite sample of Zaritsky et al. (1997). We present 3D light profiles of the centers of these satellites, and discuss how we plan to use the profiles to study the survival or disruption of satellites in minor mergers, an issue that

We present the integrated Hα emission line profile for 157 HII regions in the central 3.4 × 3.4 arcmin2 of the galaxy M83 (NGC 5236). Using the Fabry-Perot interferometer GHαFAS, on the 4.2-m William Herschel Telescope on La Palma, we show the importance of a good characterization of the instrumental response function for the study of line profile