Very Large Array7 neutral hydrogen observations of the shell elliptical galaxy NGC 3656 reveal an edge-on, warped minor-axis gaseous disk (MHI~2×109 Msolar) extending 7 kpc. H I is also found outside the optical image, on two complexes to the northeast and northwest that seem to trace one or two tidal tails, or possibly an outer broken H I disk or

We explore the stability of different galaxy light concentration indices as a function of the outermost observed galaxy radius. With a series of analytical light-profile models, we show mathematically how varying the radial extent to which one measures a galaxy's light can strongly affect the derived galaxy concentration. The ``mean concentration

We simulate the characteristics of the Galactic population of radio and gamma-ray pulsars using Monte Carlo techniques. At birth, neutron stars are spatially distributed with supernova-kick velocities in the Galactic disk and randomly dispersed in age over the past 109 years. From their birth location, the neutron stars are evolved in the Galactic

We simulate the characteristics of the Galactic population of radio and gamma-ray pulsars using Monte Carlo techniques. At birth, neutron stars are spatially distributed with supernova-kick velocities in the Galactic disk and randomly dispersed in age back to 109 years. They are evolved in the Galactic gravitational potential to the present time

In this paper we present the first comprehensive results extracted from the spectroscopic campaigns carried out by the EXPORT (EXoPlanetary Observational Research Team) consortium. During 1998-1999, EXPORT carried out an intensive observational effort in the framework of the origin and evolution of protoplanetary systems in order to obtain clues on

We present low and high resolution long-slit spectra of three bipolar planetary nebulae (PNe) with bright central cores: A 79, He 2-428 and M 1-91. He 2-428 and M 1-91 have high density (from 103.3 to 106.5 cm-3) unresolved nebular cores that indicate that strong mass loss/exchange phenomena are occurring close to their central stars. An F0 star is