The physical interpretation of spectropolarimetric observations of lines of neutral helium, such as those of the 10830 Å multiplet, represents an excellent opportunity for investigating the magnetism of plasma structures in the solar chromosphere. Here we present a powerful forward modeling and inversion code that permits either to calculate the

Accurate photometry with HST's ACS shows that the main sequence (MS) of the globular cluster NGC 2808 splits into three separate branches. The three MS branches may be associated with the complexities of the cluster's horizontal branch and of its abundance distribution. We attribute the MS branches to successive rounds of star formation, with

The spectroscopic observations were conducted during several runs spanning 15 years from March 1988 to June 2003. The observations from the Southern Hemisphere were carried out in most cases at the European Southern Observatory (ESO, La Silla, Chile) with the 1.5m ESO telescope, equipped with a Boller & Chivens spectrograph. The first and last runs

One of the most useful diagnostic tools for the detection of inclined magnetic fields in solar chromospheric and coronal structures is that based on the fact that the Hanle effect in forward scattering at the solar disk center creates linear polarization in some spectral lines, such as those of the He I 10830 Å multiplet. Here we show the

We have studied the spatial clustering of high redshift (z > 1) extremely red objects (EROs) as a function of photometric redshift in the GOODS Southern Field using public data. A remarkable overdensity of extremely red galaxies (I - Ks > 4) is found at an average photometric redshift zphot = 1.10. Nine objects (six are EROs) within 50 arcsec of

We discuss the prospects for detecting the Rees-Sciama (RS) effect associated with merging clusters of galaxies in millimetric observations. Using the extended Press-Schechter formalism, we characterize the distribution of the parameters describing the mergers, and use these results to generate a mock catalogue of cluster mergers. We use realistic