This paper reviews some of the developments that over the last 10 years have allowed us to go from deciphering the physical origin of several of the enigmatic features of the second solar spectrum to discovering unknown aspects of the Sun's hidden magnetism via sophisticated radiative transfer modeling. The second solar spectrum is the

We consider the massive star formation properties, radial profiles, and atomic gas masses of those galaxies in our Hα Galaxy Survey that have close companion galaxies, in comparison with a matched control sample of galaxies without companions. Our analysis is based on Hα and continuum images of 327 disk galaxies that form a representative sample of

We quantify the evolution of the spiral, S0 and elliptical fractions in galaxy clusters as a function of cluster velocity dispersion (σ) and X-ray luminosity (LX ) using a new database of 72 nearby clusters from the Wide-Field Nearby Galaxy-Cluster Survey (WINGS) combined with literature data at z = 0.5-1.2. Most WINGS clusters have σ between 500

Aims: We present new measurements of the abundances of carbon and oxygen derived from high-excitation C i and O i absorption lines in metal-poor halo stars, with the aim of clarifying the main sources of these two elements in the early stages of the chemical enrichment of the Galaxy. Methods: We target 15 new stars compared to our previous study

We present a few highlights concerning the search for short-period variable stars in four galaxies, namely IC 1613, LGS3, Cetus and Tucana, based on very deep, multi-epoch HST/ACS photometry. These are discussed in the context of the star formation histories obtained from our very deep color-magnitude diagrams. In particular, we show how the

We study the structure and evolution of the magnetic field of the quiet Sun by investigating weak spectro-polarimetric signals. To this end, we observed a quiet region close to the disk center with the German VTT in Tenerife, July 07, 2006. We recorded 38 scans of the same area. Each scan was eight arcsec wide and observed within about 100 seconds