The PICARD mission is a CNES micro-satellite to be launched in 2009. Its goal is to better understand the Sun and the potential impact of its activity on earth climate by measuring simultaneously the solar total and spectral irradiance, diameter, shape and oscillations. We present the scientific objectives, instrumental requirements and data

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GHαFaS, a new Fabry-Perot system, is now available at the William Herschel Telescope (WHT). It was mounted, for the first time, at the Nasmyth focus of the 4.2-m WHT on La Palma in 2007 July. Using modern technology, with a spectral resolution of the order R˜15,000, and with a seeing-limited spatial resolution, GHαFaS will provide a new look at the

A new scanning Fabry-Perot system will soon be available at the Nasmyth focus of the 4.2 m William Herschel Telescope. It has been designed by the Laboratoire d'Astrophysique Expérimentale in Montréal and is being built in collaboration with astronomers at the Instituto de Astrofísica de Canarias. The instrument will see first light at the

We have analyzed the effects of gas on the disk-halo evolution in barred galaxies using N-body/SPH simulations. Our main focus has been the angular momentum (J)~redistribution mediated by the stellar bar and the subsequent evolution of the galactic disk. We find that the stellar bars in disks with 0-8 percent gas fraction are primarily affected by

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