Context: .Sunspot penumbrae harbor highly structured magnetic fields and flows. The moving flux tube model offers an explanation for several observed phenomena, e.g. the Evershed effect and bright penumbral grains. Aims: .A wealth of information can be extracted from spectropolarimetric observations. In order to deduce the structure of the magnetic

There are some 194,000 R = 2000 stellar spectra reported in the final public release of the Sloan Digital Sky Survey (SDSS-I), known as DR-5. Setting aside the stars observed during the course of early tests for the Sloan Extension for Galactic Understanding and Exploration (SEGUE), which will be considered in the future, this leaves a total of

The spectral lines observed in penumbrae are asymmetrical, revealing the existence of spatially unresolved structures. We infer their physical properties by fitting Stokes spectra of Fe I 6301.5 Å and Fe I 6302.5 Å with model atmospheres having two magnetic components interleaved along the line-of-sight (LOS). Combining ten thousand fits, we set up

As part of The HST/ACS Survey of Galactic Globular Cluster, we have imaged the globular clusters that are canonical members of the Sagittarius dSph galaxy (Sgr), including M54, which is either in or along the line of sight of the core of the Sagittarius dSph. The M54 field CMD, which extends to more than five magnitudes below the M54 main sequence

Based on our large and homogeneous photometric database of globular cluster observations taken with the Advanced Camera for Surveys aboard the Hubble Space Telescope, a set of distance and reddening independent relative age indicators have been measured. The high quality of the color magnitude diagrams (CMDs) allows us to explore several variations

The HST/ACS Survey of Galactic globular clusters is a Treasury project designed to obtain photometry with S/N ≥10 for main sequence stars with masses ≥ 0.2M&sun; in a large sample of globulars using the Advanced Camera for Surveys (ACS) Wide Field Channel. We plan to use these data to address a range of astrophysical questions. Here we present new