We report the results of narrow band imaging of the bipolar outflow source NGC 2818 in transitions of [NII], [OIII], [SII], and HI. As a consequence, we are able to assess the overall excitation properties of the shell, and determine that line ratios towards the nebular periphery are anomalous, and characteristic of planar shocks with velocity V_s

The interpretation of detailed spectroscopic observations of different stars reveals inconsistencies, due likely to inadequacies of the underlying hypothesis. The high accuracy of the parallaxes measured by the Hipparcos satellite established a firm reference frame that is used here to test theoretical classical model atmospheres for cool stars

As part of an extensive multiwavelength monitoring campaign, the International Ultraviolet Explorer satellite was used to observe the broad-line radio galaxy 3C 390.3 during the period 1994 December 31-1996 March 5. Spectra were obtained every 6-10 days. The UV continuum varied by a factor of 7 through the campaign, while the broad emission lines

A recent paper by King & Ritter proposed that the light curves of soft X-ray transients (SXTs) are dominated by the effect of irradiation of the accretion disc by the central X-rays. This prevents the onset of the cooling wave which would otherwise return the disc to the quiescent state, and so prolongs the outbursts beyond those in dwarf nova

A new approach to the study of the large-scale stellar cluster distribution in the Galaxy based on two-point correlation techniques is presented. The basic formalism for this method is outlined, and its applications are then investigated by the use of a simple model of cluster distribution in the Galaxy. This provides an estimate of the potentials

We present preliminary results on high resolution Hα imaging of the Wolf-Rayet blue compact dwarf galaxy (BCDG) Mrk 1094. This galaxy presents a bar-shape structure and is currently undergoing a strong star formation burst distributed in several knots. Spatially resolved photometry of the different knots indicates that star formation seems to be