Narrow-band Hα and [Nii] images and high-dispersion spatially resolved echelle spectroscopy of the planetary nebula NGC 6891 are presented. These observations show a great wealth of structures. The bright central nebula is surrounded by an attached shell and a detached outer halo. Both the inner and intermediate shells can be described as

The purpose of this study is to carry out a thorough investigation of the changes in morphology of the red giant branch (RGB) of Galactic globular clusters (GGC) as a function of metallicity, in the V,I bands. To this aim, two key points are developed in the course of the analysis. (a) Using our photometric V,I database for Galactic globular

Four or five new outbursts were detected of the bright X-ray transient GRS 1747-312 in the globular cluster Terzan 6 between 1996 and 1999, through monitoring campaigns with the Wide Field Cameras (WFCs) on BeppoSAX and the Proportional Counter Array (PCA) on RossiXTE. This is the first time that the source is seen to exhibit recurrent outbursts

The spiral galaxy NGC 3359 has been observed in the Hα line with the TAURUS II Fabry-Perot interferometer at the William Herschel Telescope within the BARS programme on the Canary Island telescopes in order to study the kinematics of the ionized gas. We have produced maps of velocity and velocity dispersion, and computed the rotation curve out to ~

The far-UV spectrum of the T Tauri stars (TTSs) provides important clues about the structure of the stellar atmospheres, winds and accretion shocks. The IUE (International Ultraviolet Explorer) Final Archive contains the most complete data base for such studies. A new extraction system, the IUE Newly Extracted Spectra (ines), has been developed to

The planetary nebula M2-9 has drastically changed its shape since its discovery by Minkwoski. Although the outline of the nebula seems to be stationary, most of the knots and bright features (N1, N2, S1, and S2) have moved laterally from the west to the east edges of both lobes. These features and their changes have reflection, not point, symmetry