Context. The mechanisms giving rise to diffuse radio emission in galaxy clusters and, in particular, their connection with cluster mergers are still being debated. Aims: We explore the internal dynamics of Abell 2254, which has been shown to host a very clumpy and irregular radio halo. Methods: Our analysis is mainly based on redshift data for 128

We took simultaneous observations in Fe I 1.5 µ and Fe I 630 nm of an internetwork region. We discuss the compatibility of the data in the two spectral ranges, and present results for the magnetic field distribution. We show that the larger contribution comes from hG field strengths.

During the first few nights following its discovery, we observed the interstellar Ca II and Na I lines towards supernova 1993J at high spectral resolution (full width half maximum (FWHM) approximately 5-6 km/s) with the William Herschel Telescope at La Palma. We find a crowd of absorption components in the radial-velocity range -135 km/s less than

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Since the early 1970s, inversion techniques have become the most useful tool for inferring the magnetic, dynamic, and thermodynamic properties of the solar atmosphere. Inversions have been proposed in the literature with a sequential increase in model complexity: astrophysical inferences depend not only on measurements but also on the physics

We present an analysis of simultaneous observations of a sunspot in two different spectral ranges (630 nm and 1565 nm). The dataset was acquired with the POlarimetric LIttrow Spectrograph (POLIS) and the Tenerife Infrared Polarimeter (TIP) at the German Vacuum Tower Telescope (VTT) of Observatorio del Teide. Inversions of both sets of lines are