Spectroscopic observations of the fast X-ray transient and superluminal jet source SAX J1819.3-2525 (V4641 Sgr) reveal a best fitting period of P spect=2.81678+/- 0.00056 days and a semiamplitude of K2=211.0+/- 3.1 km s-1. The optical mass function is f(M)=2.74+/- 0.12 Msun. We find a photometric period of P photo=2.81730 +/- 0.00001 days using a

VII Zw403 is a nearest BCD galaxy. This izolated system is so close (~4.5 Mp c), that it makes it possible to study it's star forming regions with unprecedently great details. recent X-ray observations (Papaderos et al. 1994) added more interest to the system, as revealed an extended, kpc-scale region of the diffuse X-ray emission. We use our

Here is a state-of-the-art review of our current knowledge of brown dwarfs and very low-mass stars. The hunt for, and study of, these elusive objects is currently one of the most dynamic areas of research in astronomy. This volume presents review articles from a team of international authorities who assess the spectacular progress in this field in

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We present a complete study of the diffuse ionized gas (DIG) in a sample of six spiral galaxies (NGC 157, NGC 3359, NGC 3631, NGC 6764, NGC 6951, NGC 7479) using very high quality Hα images which allow analysis down to very low surface brightness (between 0.3 and 2 pc cm-6). Separation of the diffuse Hα emission from that of the H II regions was

We present a gallery with some of the most interesting microstructures of low-ionization found in planetary nebulae (PNe). A rich zoo of knots, filaments, jets and jet-like systems are introduced, together with their morphological and kinematic properties. We briefly compare the predictions of the theoretical mechanisms for their formation with the