As part of the ACS Survey of Galactic Globular Clusters, we present new Hubble Space Telescope photometry of the massive globular cluster M54 (NGC 6715) and the superposed core of the tidally disrupted Sagittarius (Sgr) dSph galaxy. Our deep (F606W ~ 26.5), high-precision photometry yields an unprecedentedly detailed color-magnitude diagram showing

Aims:A-type asteroid (1951) Lick has a very red visible and near-infrared reflectance spectrum, and it is one of the reddest Near-Earth objects. Its surface is probably affected by heavy space weathering processes. Here we investigate the possibility of a weathering saturation regime. Methods: We compare Lick's spectrum with those of silicate

We present a preliminary analysis of ASTRO-F data of a complete sample of ~150 EROs (R-K>5) down to K(Vega)

We present resolved-star VI photometry of the Local Group dwarf irregular galaxy IC 1613 reaching I ~ 23.5, obtained with the wide-field camera at the 2.5 m Isaac Newton Telescope. A fit to the stellar density distribution shows an exponential profile of scale length 2.9' ± 0.1' and gives a central surface brightness μV,0 = 22.7 ± 0.6. The

We present a homogeneous set of stellar atmospheric parameters (Teff, logg, [Fe/H]) for MILES, a new spectral stellar library covering the range {lambda}{lambda}3525-7500{AA} at 2.3{AA} (FWHM) spectral resolution. The library consists of 985 stars spanning a large range in atmospheric parameters, from super-metal-rich, cool stars to hot, metal-poor

We present a study of the optical spectra of a sample of eight star-forming nuclear rings and the nuclei of their host galaxies. The spectra were obtained with the Intermediate dispersion Spectrograph and Imaging System spectrograph on the William Herschel Telescope and cover a wide range in wavelength, enabling the measurement of several stellar