An important test for models of galaxy formation lies in the metallicity distribution functions (MDFs) of spheroid stars and their globular clusters (GCs). We have compared the MDFs obtained from spectroscopy of the GCs and the star-by-star photometry of the old halo red giants in the nearby elliptical galaxy NGC 5128, with the predictions of a Λ

We present two-dimensional numerical simulations of the evolution of a low-mass star moving supersonically through its surrounding interstellar medium (ISM). We show that the ejecta of a moving star with a systemic velocity of 20 km s-1 will interact with the ISM and will form bow shock structures qualitatively similar to what is observed. We find

We employ the magnetic and velocity fields from turbulent dynamo simulations to synthesize the polarization of a typical photospheric line. The synthetic Stokes profiles have properties in common with those observed in the quiet Sun. The simulated magnetograms present a level of signal similar to that of the Inter-Network regions. Asymmetric Stokes

OSIRIS (Optical System for Imaging and low Resolution Integrated Spectroscopy) is the optical Day One instrument for the 10.4m Spanish telescope GTC to be installed in the Observatorio del Roque de Los Muchachos (La Palma, Spain). This instrument, operational in mid-2004, covers from 360 up to 1000 nm. OSIRIS observing modes include direct imaging

The optics of OSIRIS, a versatile first generation imager/spectrograph, for the 10.4-m Gran Telescopio Canarias (GTC), has undertaken its manufacturing phase. Brief descriptions of the design characteristics and expected performance are given. Current advances in a relevant optical study (throughput) are summarized as well as the status of

Elmer is a visible imager and spectrograph for the Gran Telescopio Canarias, which has been designed in-house. The major features and some of the analysis done are shown for each optical assembly. The image error budget is presented with the current estimations, as well as the foreseen acceptance tests. Finally the present status of the optics is