Clusters of galaxies produce negative features at wavelengths λ > 1.25 mm in cosmic microwave background (CMB) maps by means of the thermal Sunyaev-Zel'dovich (SZ) effect, while point radio sources produce positive peaks. This fact implies that a distribution of unresolved SZ clusters could be detected using the negative asymmetry introduced in the

With the goal of confirming the metallicity ``excess'' observed in stars with planetary mass companions, we have conducted a high-precision spectroscopic study of a ``comparison'' sample of dwarfs included in the CORALIE extra-solar planet survey (Santos, Israelian, & Mayor 2001). The targets were chosen following two basic criteria: they make part

This article shows how some recent developments in the observation and theoretical modeling of weak polarization signals in chromospheric spectral lines are facilitating fundamental new advances in our ability to investigate the magnetism of the solar outer atmosphere via spectropolarimetry.

Very valuable information can be obtained by studying surface chemical abundances in stars with orbiting planets. Possible interactions between extrasolar planets and their parent stars can be studied using light elements as lithium and beryllium, which are excellent tracers of mixing mechanisms operating in the stellar interior. A wide sample of

A large-scale three-dimensional model of Galactic extinction is presented based on the Galactic dust distribution model of citet{DS01}. The extinction AV to any point within the Galactic disk can be quickly deduced using a set of three-dimensional Cartesian grids. Extinctions from the model are compared to empirical extinction measures, including

We describe the results of a search for transit-like events caused by giant planets occulting stars in the old, metal-rich open cluster NGC 6791 based on BVI-colour photometry from eight nights of observations with the 2.54 m Nordic Optical Telescope. To extract the light curves we have used both PSF photometry (DAOPHOT) and the difference imaging