One of the intents of the ground-based gamma-ray astronomy is to obtain a sky survey in the TeV energy region, and nowadays this target can be reached with giant arrays of telescopes, which however need many pointings due to their small field of view. A different approach is on the basis of GAW, acronym for Gamma Air Watch, an array of three

We report on 3 Chandra ACIS-I observations containing the two M31 transient X-ray sources announced by Haberl et al. (2006, ATel #881) and followed up by Pietsch et al. (2006, ATel #899). These observations are part of our ongoing Chandra/HST M31 transient program XMMU J004215.8+411924: This High Mass X-ray Binary was first observed with Chandra

Context: .Free-floating planetary-mass objects have masses below the deuterium burning mass limit at about 13 Jupiter masses, and have mostly been found in very young open clusters. Their origin and relationship to stars and brown dwarfs are still a mystery. Aims: .The recent detection by direct imaging of three giant planets at wide separation (50

Together with other observational methods, visible and near infra-red polarimetry can help to understand the morphology of magnetic fields in the neighborhood of several star-forming regions. Inside molecular clouds, this morphology can be deduced with the help of submm polarimetry but rarely in the same regions. When both observational methods are

Las regiones H II son objetos fundamentales para el conocimiento de la composición y la evolución química en el Universo, especialmente en el dominio extragaláctico. Debido a esto, es fundamental conocer si los métodos tradicionales de determinación de abundancias en nebulosas ionizadas (basados en el análisis de líneas de excitación colisional)

We have conducted deep photometric searches for substellar members of the Praesepe (0.5-1 Gyr) and σ Orionis (3 Myr) star clusters using the Sloan i' and z' broad-band filters, with the 3.5-m and the 5-m Hale telescopes on the Calar Alto and Palomar Observatories. The total area surveyed was 1177 arcmin2 and 1122 arcmin2 towards the central regions