ES BIEN SABIDO QUE LA TURBULENCIA ATMOSFÉRICA LIMITA LAS PRESTACIONES DE LOS GRANDES Y EXTRA-GRANDES TELESCOPIOS POR ELLO ES IMPRESCINDIBLE DESARROLLAR ESTRATEGIAS E INSTRUMENTOS QUE SOSLAYEN ESTA LIMITACIONES. LA SOLUCIÓN PASA POR GENERAR ESTRELLAS ARTIFICIALES POR LASER, YA SEA EN LAS CAPAS BAJAS POR SCATTERING RAYLEYGH O EN LA MESOPAUSA A PARTIR

We report in this paper on the design and progress of the ESO Laser Guide Star Facility. The project will create a user facility embedded in UT4, to produce in the Earth's Mesosphere Laser Guide Stars, which extend the sky coverage of Adaptive Optics systems on the VLT UT4 telescope. Embedded into the project are provisions for multiple LGS to cope

Using a near-infrared stellar library of 706 stars with a wide coverage of atmospheric parameters, we study the behaviour of the CaII triplet strength in terms of effective temperature, surface gravity and metallicity. Empirical fitting functions for recently defined line-strength indices, namely CaT*, CaT and PaT, are provided. These functions can

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As a parallel result of an IT Project aimed at determining accurate distances to more than 30 planetary nebulae using the extinction-distance method, we report here the serendipitous discovery of a giant halo around NGC 7027. We obtained the spectra of more than 60 field stars around each PN with the LDSS multi-slit spectrograph at the 4.2-m

We present four lines of evidence leading to the conclusion that a notable fraction of the ionizing photon emission from the stars within H II regions in the disks of normal galaxies escapes from the regions into the surrounding galaxy and beyond. These are: (1) The surface brightness intensity distribution of the diffuse ensuremath {{Hα }} emitted