Context. Recent observations of various kinds of jets in the solar atmosphere motivate studying the influence of mass flow on the stability of solar magnetic structures. Aims: We study the influence of axial mass flows on the stability of twisted magnetic flux tubes. Methods: We use the incompressible magnetohydrodynamic equations to get the

We report unusual near- and mid-infrared photometric properties of G 196-3 B, the young substellar companion at 16'' from the active M2.5-type star G 196-3 A, using data taken with the IRAC and MIPS instruments onboard Spitzer. G 196-3 B shows markedly redder colors at all wavelengths from 1.6 up to 24 μm than expected for its spectral type, which

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The integration and verification phase of the GREGOR telescope reached an important milestone with the installation of the interim 1 m SolarLite primary mirror. This was the first time that the entire light path had seen sunlight. Since then extensive testing of the telescope and its subsystems has been carried out. The integration and verification

We perform N-body simulations of a minor merger between a Milky Way like galaxy and a disk-like satellite. In this set of collisionless runs we vary critical parameters such as the luminous mass ratio between the two galaxies (1:6, 1:9), the type of orbit (direct or retrograde) and the number of particles (185,000, 555,000 and 1,850,000). We

We study the response of the low-degree solar p-mode frequencies to the unusual extension of the minimum of solar surface activity since 2007. Helioseismic observations collected by the space-based, Sun-as-a-star GOLF instrument and by the ground-based, multi-site network GONG (integrated signal) are analyzed. Temporal variations of the low-degree