An analysis of a new and extensive set of spectroscopic observations of the early-type binary system {AR Cas} , based also on spectral disentangling, has led to the discovery of the spectrum of the secondary star and of line-profile variations of the B4V primary star. A revised spectroscopic orbit based on these and published data is presented. We

We present time-resolved optical spectroscopy of the cataclysmic variable S193. The emission lines are remarkably similar to those of V795 Her and exhibit high-velocity S-waves and complex absorptions that are modulated with the orbital period. Evidence for transient anomalous spectral features is seen during the first two nights of our run. We

Since the 1960s, ground-based radio astronomers have had the capability to image solar radio emissions using aperture synthesis techniques. These images show the two-dimensional time history of CME-driven shock fronts, for example. However, ground-based observations are limited by the terrestrial ionosphere to frequencies above about 15 MHz, which

We have measured the equivalent width WK of the K i resonance line at 7699 Angstroms for a large sample of low activity late-type stars observed with high spectral resolution and we have verified that the relation WK vs. Teff is monotonically decreasing, for both dwarf and giant stars. This behaviour is different from that of the Na I D lines for

We report YALO consortium observations using the Yale 1-m telescope at CTIO and observations with the 48" telescope at the Whipple Observatory: Aql X-1 = V1333 Aql appears to be beginning a new outburst. This x-ray binary outbursts approximately once per year, and based on its recent outbursts was due to erupt.

We discuss the energy budget of AGN jets, based on available data for all 14 having detected optical synchrotron emission. Assuming equipartition between magnetic field and particle energy, these jets transport enough kinetic energy to power a typical extended radio lobe only if the bulk motion of the jet plasma is at least moderately relativistic