We present new near-infrared (J and K) magnitudes for 114 RR Lyrae stars in the globular cluster ω Centauri (NGC 5139), which we combine with data from the literature to construct a sample of 180 RR Lyrae stars with J and K mean magnitudes on a common photometric system. This is currently the largest such sample in any stellar system. We also

We study the delay induced by gravitational light bending in the arrival times of signals emitted by an anisotropic source in rotation (pulsar). The shift of the direction of the allowed pulsar beam (a vector defined by the null geodesic connecting the pulsar to the observer) with orbital phase induces a delay arising from the movement of the

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