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A representative set of profiles is presented for the Ca II H resonace line in Stokes V and I, for the quiet sun, plages, sunspot umbrae, and a flare, as well...

We have studied a sample of selected eclipsing binaries with eccentric orbits and accurate absolute dimensions in order to analyse the validity of available...

We report broad-band imaging observations which reveal a circum-nuclear gas ring in NGC 4151. The ring is delineated by two arc-like features probably resulting...

We investigate the properties of circumgalactic gas in the halo of quasar (QSO) host galaxies from C IV absorption-line systems. We use the optical spectroscopy...

We have used the Nordic Optical and the William Herschel Telescopes to obtain images and long-slit spectra of Cygnus A under conditions of sub-arcsecond seeing...

We present for the first time a two-dimensional velocity field of the central region of the grand-design spiral galaxy NGC 5248, at 0.9-arcsec spatial...

We present subarcsecond-resolution, ground-based, near-infrared images of the central regions of a sample of 12 barred galaxies with circumnuclear star...

We present optical broad- and narrow-band imaging of a sample of a dozen barred galaxies. These images are analysed in conjunction with our previously published...