In this brief note we remark that the four spatially resolved relativistic radio jets among the 14 dynamically confirmed black hole x-ray novae are all in systems with long orbital periods. Many shorter period systems show transient radio outbursts which are attributed to jets, but these jets have not been resolved. Super-Eddington accretion has

A possible discrepancy found between the determination of mass of the intracluster medium (ICM) from gravitational lensing data and that from X-ray observations has been much discussed in recent years. For instance, Miralda-Escudé & Babul found that the mass estimate derived from gravitational lensing can be as much as a factor of 2-2.5 larger than

We introduce an iterative spectral disentangling technique combined with Doppler imaging in order to recover surface temperature maps for both components of double-lined active binary systems. Our method provides an opportunity to separate spectra of the active components while minimizing the unwanted disturbances on the given line profile from the

An international monitoring project, called OJ-94, was set up with the aim of monitoring blazar OJ 287 during the predicted optical outburst (in fall 1994, Sillanpaa et al. 1988ApJ...325..628S) and the predicted secondary outburst (in winter 1995-1996, Sillanpaa et al. 1996A&A...305L..17S). The most prominent features in the OJ 287 light curve

We report the first spectroscopic detection of the secondary star in the X-ray transient QZ Vul (=GS 2000+25). Cross-correlation of individual spectra against K-type templates yields clear velocity modulations with the 8.3-h orbital period. From the amplitude of the radial velocity curve (520+/-16 km s^-1) we derive a mass function f(M)=5.02+/-0.46

Binary brown dwarfs are important because their dynamical masses can be determined in a model-independent way. If a main sequence star is also involved, the age and metallicity for the system can be determined, making it possible to break the sub-stellar mass-age degeneracy. The most suitable benchmark system for intermediate age T dwarfs is ɛ Indi