Context. The optical ring-like structure detected by Arp (1965) around M 81 (commonly referenced as “Arp's loop”) represents one of the most spectacular features observed in nearby galaxies. Arp's loop is commonly interpreted as a tail resulting from the tidal interaction between M 81 and M 82. However, since its discovery the nature of this

Nuclear disks and rings are frequent galaxy substructures, for a wide range of morphological types [from S0 to Sc, see e.g., 1, 2]. We have investigated the possible minor-merger origin of inner disks and rings in spiral galaxies through collisionless N-body simulations. The models confirm that minor mergers can drive the formation of thin

We investigate the thermodynamical and magnetic properties of a ``dark-cored" fibril seen in the chromospheric Ca II IR line at 854.2 nm to determine the physical process behind its appearance. We analyse a time series of spectropolarimetric observations obtained in the Ca II IR line at 854.2 nm and the photospheric Fe I line at 630.25 nm. We

We analyze radio continuum and line observations from the archives of the Very Large Array (VLA), as well as X-ray observations from the Chandra archive of the region of massive star formation W75N. Five radio continuum sources are detected: VLA 1, VLA 2, VLA 3, Bc, and VLA 4. VLA 3 appears to be a radio jet; we detect J = 1-0, v = 0 SiO emission

Aims: We attempt to detect starlight reflected from the hot Jupiter orbiting the main-sequence star τ Boo, in order to determine the albedo of the planetary atmosphere, the orbital inclination of the planetary system and the exact mass of the planetary companion. Methods: We analyze high-precision, high-resolution spectra, collected over two half

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