An optically and geometrically thick torus obscures the central engine of active galactic nuclei (AGN) from some lines of sight. From a magnetohydrodynamical framework, the torus can be considered to be a particular region of clouds surrounding the central engine where the clouds are dusty and optically thick. In this framework, the magnetic field

Magnetic field plays a crucial role to understand most phenomena happening in the solar atmosphere. Sunspots, flares, prominences, coronal mass ejections are well known examples of its interaction with the solar plasma. To study the properties of this interaction, one needs to analyze the imprint it leaves in the radiation through the polarization

We investigate the suitability of GTC/OSIRIS Tunable Filters (TFs) for obtaining emission-line maps of extended objects. We developed a technique to reconstruct an emission-line image from a set of images taken at consecutive central wavelengths. We demonstrate the feasibility of the reconstruction method by generating a flux calibrated Hα image of

We have used the tuneable filter system of OSIRIS to observe the [SII] doublet lines at λλ617.7 and 673.1 nm in emission across the full face of NGC 6946, and estimated the in situ electron densities for 387 HII regions, so far. The values decline steadily from over 350 cm^-3 at 1/3 R_{25} to around 175 cm^-3 at 2/3 R_{25}.

Context. The unified model of active galactic nuclei (AGN) claims that the properties of AGN depend on the viewing angle of the observer with respect to a toroidal distribution of dust surrounding the nucleus. Both the mid-infrared (MIR) attenuation and continuum luminosity are expected to be related to dust associated with the torus. Therefore

Numerical simulations of double-barred galaxies predict the build-up of different structural components (e.g. bulges, inner discs) in the central regions of disc galaxies. In those simulations, inner bars have a prominent role in the internal secular evolution of their host galaxies. The development of bulges and inner discs is, however, poorly