The physical interpretation of the spectral line polarization produced by the joint action of the Hanle and Zeeman effects offers a unique opportunity to obtain empirical information about hidden aspects of solar and stellar magnetism. To this end, it is important to achieve a complete understanding of the sensitivity of the emergent spectral line

A promising approach to decrease the uncertainties in the initial--final mass relationship, which is still poorly constrained, is to study white dwarfs for which external constraints are available, for instance, white dwarfs in common proper motion pairs (CPMPs). Important information of the white dwarf can be inferred from the study of the

From observations of almost 500 red giant branch stars in 29 Galactic open and globular clusters, we have investigated the behavior of the infrared Ca II triplet (8498, 8542, and 8662 Å) in the age range 13 Gyr

The emergence of magnetic flux from the convection zone into the corona is an important process for the dynamical evolution of the coronal magnetic field. In this paper we extend our previous numerical investigations, by looking at the process of flux interaction as an initially twisted flux tube emerges into a plane-parallel, coronal magnetic

CODEX, a high resolution, super-stable spectrograph to be fed by the E-ELT, the most powerful telescope ever conceived, will for the first time provide the possibility of directly measuring the change of the expansion rate of the Universe with time and much more, from the variability of fundamental constants to the search for other earths. A study

As part of the ACS Survey of Galactic Globular Clusters, we present new Hubble Space Telescope photometry of the massive globular cluster M54 (NGC 6715) and the superposed core of the tidally disrupted Sagittarius (Sgr) dSph galaxy. Our deep (F606W ~ 26.5), high-precision photometry yields an unprecedentedly detailed color-magnitude diagram showing