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

The search for optical emission from radio hot spots has a long history but, up to now, only very few hot spots with optical synchrotron radiation have been detected. We embarked on a project to search for optical hot spot emission with VLT. We present the first results of near-infrared and optical imaging observations which detected synchrotron

We present a new general procedure for determining a given set of quantities. To this end, we define a certain statistic, which we call `modified χ2' (χ2M), because of its similarity to the standard χ2. The terms of this χ2M are made up of the fluctuations of an unbiased estimator of some statistical quantities and certain weights. Only the