The blue supergiant Sher25 is surrounded by an asymmetric, hourglass-shaped circumstellar nebula. Its structure and dynamics have been studied previously through high-resolution imaging and spectroscopy, and it appears dynamically similar to the ring structure around SN1987A. Here, we present long-slit spectroscopy of the circumstellar nebula

Laser Guide Stars -LGS- has been widely proposed to extend the domain of stable operation for adaptive optics systems in large telescopes. As LGS are formed in a finite distance, bistatic schemes with two or more additional telescopes has been noted as the most efficient configuration from the point of view of full aperture tip-tilt correction. In

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