Aims: One of the most striking features predicted by standard models of galaxy formation is the presence of anti-correlations in the matter distribution on large enough scales (r > r_c). Simple arguments show that the location of the length scale r_c, marking the transition from positive to negative correlations, is the same for any class of

We measure the radial velocity curve of the eclipsing detached white dwarf binary NLTT 11748. The primary exhibits velocity variations with a semi-amplitude of 273 km s-1 and an orbital period of 5.641 hr. We do not detect any spectral features from the secondary star or any spectral changes during the secondary eclipse. We use our composite

We present very accurate orbital parameters and mass measurements (2.4% accuracy) for the well known very low mass triple system Gl 866. We obtain first orbital elements for the short-period orbit and greatly improve the long period orbit. All three stars have masses close to 0.1 M_sun, and the system thus provides the strongest constraints to date

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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