The Sloan Digital Sky Survey (SDSS) is collecting photometry and intermediate resolution spectra for ˜105 stars in the thick-disk and stellar halo of the Milky Way. This massive dataset can be used to infer the properties of the stars that make up these structures, and considerably deepen our vision of the old components of the Galaxy. We devise

Two time series, taken simultaneously in the G-band and the blue continuum, corrected for instrumental and atmospheric degradation using the method of phase diversity, are employed to study the motions of granules and G-band bright points (GBPs) in the moat of an old regular sunspot. Centres of diverging horizontal motions, identified with families

The Nuker model, when applied to the inner regions of ``core'' galaxies, is shown to produce systematic biases in the determination of the core ``break-radii''. These radii can easily be (and often have been, see Trujillo et al. 2003) over-estimated by more than 100%. Moreover, due to curvature in the outer profiles of early-type galaxies (i.e

The Ca II triplet is one of the most frequently measured features for deriving stellar metallicities from moderate resolution spectroscopy of red giants in old and metal poor systems. With the advent of 8m class telescopes, this indicator becomes of invaluable help in deriving metallicities for large samples of faint stars in the Local Group, and

We have calculated the evolution of a 0.49 Msolar hydrogen deficient white dwarf up to very low effective temperatures. The final model has been obtained by calculating the evolution of a H-deficient star from the extreme horizontal branch (EHB) up to the white dwarf regime, without going through the asymptotic giant branch (AGB). Progenitor stars

This work explore the formation and evolution of hydrogen-deficient post-AGB white dwarfs. To this end, we compute the complete evolution of an initially 2.7 M sun star from the ZAMS through the thermally pulsing and mass-loss phases to the white dwarf stage. Particular attention is given to the chemical abundance changes during the whole evolution