We have been testing at laboratory commercial variable attenuators commonly used in telecommunication applications for their used in astronomy. Such variable attenuators are going to be included in the central fibers of the integral field unit (IFU) of the prototype instrument EDiFiSE (Equalized and Diffraction-limited Field Spectrograph Experiment

Aims: To improve our understanding of substellar formation, we have performed a compositional and structural study of a brown dwarf disk. Methods: We present the results of photometric, spectroscopic, and imaging observations of 2MASS J04442713+2512164, a young brown dwarf (M 7.25) member of the Taurus association. Our dataset, combined with

To understand the formation and evolution of solar-type stars in the solar neighborhood, we need to measure their stellar parameters to high accuracy. We present a catalogue of accurate stellar parameters for 451 stars that represent the HARPS Guaranteed Time Observations (GTO) “high precision” sample. Spectroscopic stellar parameters were measured

We review recent advances in our understanding of massive stars through the analysis of their spectra. Improvements in model atmospheres and analysis methods are briefly discussed. Results obtained for stars in the Local Group are compared and the present status of different open questions, like the temperature scale of OB stars, the Wind Momentum

We propose to observe six fields in the nearby dwarf spheroidal galaxy (dSph) Sculptor in order to study the stellar populations, and in particular their spatial gradients, through RR Lyrae star populations and deep color-magnitude diagrams (CMD). In addition to provide a complete census of its short-period variable stars, we will use the pulsation

Very high resolution (R>150,000) spectra of a small sample of nearby K-dwarfs have been acquired to measure the line asymmetries and central wavelength shifts caused by convective motions present in stellar photospheres. This phenomenon of granulation is modeled by 3D hydrodynamical simulations but they need to be confronted with accurate