A substellar-mass object in orbit at about 300 astronomical units (AU) from the young low-mass star G196-3 was detected by direct imaging. Optical and infrared photometry and low- and intermediate-resolution spectroscopy of the faint companion, hereafter referred to as G196-3B, confirms its cool atmosphere and allows its mass to be estimated at 25^

We present the discovery of the first white dwarf + T dwarf binary system. Systems containing a white dwarf and a brown dwarf are rare but can be used to place constraints on the age of the binary, making them valuable benchmark systems. It is currently not possible to calculate brown dwarf ages from models alone and white dwarfs provide an

We present the analysis of photometric and spectroscopic data of two bright Galactic Cepheids, X Puppis and XX Sagittarii. Based on the available data in the literature as well as our own observations spanning 75 years, we conclude that both Cepheids belong to spectroscopic binary systems. However, the data are not sufficient to determine the

The knowledge of accurate distances to Planetary Nebulae (PNe) is necesary in order to improve the determination of some physical quantities such as the nebular radius and mass. The nebular mass is a critical parameter to determine the amount of mass that is returned to the interstellar medium by the PN. This mass return can influence the evolution

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