Narrow-band CCD images of 209 axially symmetrical planetary nebulae (PNe) have been examined in order to determine the orientation of their axes within the disc of the Galaxy. The nebulae have been divided into the bipolar (B) and elliptical (E) PNe morphological types, according to the scheme of Corradi & Schwarz. In both classes, contrary to the

We present the first results of a survey carried out on a sample of optically bright post-AGB candidates selected from the IRAS Point Source Catalogue, many of them previously unidentified in the literature. The selection criteria are based on their characteristic far infrared colours. Low resolution spectroscopy of more than 150 sources has been

We present a study of the [α/Fe-peak] and [N/α] abundance ratios in Damped Lyα (DLA) systems. By using ratios of undepleted elements ([S/Zn] and [N/S]) or when abundances of refractory elements are corrected by dust depletion ([Si/Fe]corr), the resulting ratios do not resemble those observed in the Galactic metal-poor stars, showing instead

We obtain the RPA summed one-meson exchange potential between nucleons in symmetric nuclear matter at zero temperature, from a model which includes $ ho $, $sigma $, $omega $ and $pi $ mesons. The behavior of rho mesons inside the medium is first discussed using different schemes to extract a finite contribution from the vacuum polarization. These

The major purpose of this paper is to investigate the nature of planetary nebulae (PNe) candidates in the southern hemisphere, taken from an internal list. We present spectroscopic observations and imaging of six PNe identified for the first time. Another candidate turned out to be a galaxy. All observed PNe represent evolved stages, their angular

Not Available