The first theoretical investigation of the formation of the linearly polarized solar line spectrum of a complex atom, neutral titanium, is presented. The process of formation of line polarization is modeled by simply considering a plane-parallel layer of Ti I atoms illuminated from below by the photospheric radiation field, and accounting for the

We make a quantitative comparison between spectral vs filter measurement and analysis techniques for extraction of solar vector magnetic fields from polarimetric data using as a basis the accurately calibrated, high angular resolution. Stokes profile data from the Advanced Stokes Polarimeter. It is shown that filter-based measurements deliver

We present Very Large Telescope (VLT) UVES echelle spectrophotometry of the Orion nebula in the 3100-10400 Årange. We have measured the intensity of 555 emission lines, many of them corresponding to permitted lines of different heavy-element ions. This is the largest set of spectral emission lines ever obtained for a Galactic or extragalactic HII

In this review, we look back upon the literature, which had the GREGOR solar telescope project as its subject including science cases, telescope subsystems, and post-focus instruments. The articles date back to the year 2000, when the initial concepts for a new solar telescope on Tenerife were first presented at scientific meetings. This

We derive new spectral Hγ index definitions that are robust age indicators for old and relatively old stellar populations and therefore have great potential for solving the age-metallicity degeneracy of galaxy spectra. To study this feature as a function of age, metallicity, and resolution, we have used a new spectral synthesis model that predicts

The discovery of Li in the late type secondary of the black hole binary V404 Cyg has motivated considerable interest in the presence of this light element in stars orbiting compact objects in general. We report here on a search for Li in cataclysmic binaries (CVs), where a low mass star transfers mass onto a white dwarf. For this purpose, we have