During last years, direct evidence about oscillations in different coronal structures has been obtained thanks to the detailed observations made by SoHO and TRACE. With the help of magnetohydrodynamic (MHD) wave theory, we can explain these observations as due to the excitation and propagation of MHD waves in the solar corona. In spite that there

The proper characterisation of the turbulence structure in an astronomical site requires an statistical study of the refractive-index structure constant Cn2(h). Our team is monitoring the Cn2(h) profiles since 2002 at the Teide and Roque de los Muchachos observatories (Canary Islands, Spain) with the g-SCIDAR technique. We have compared the

The hypergiant ρ Cas is known for its variable rate of mass loss, with an average value of about 10^-5^Msun_/yr, and the supersonic value for the line-of-sight component of the microturbulent velocity, about 11km/s. Emission components in Hα suggest the presence of a thermally excited outer atmospheric region. Since hydrodynamical turbulence in a

Statistics are presented covering 20 years of use of the 2.1m telescope of the Observatorio Astronómico Nacional at San Pedro Mártir, Baja California, Mexico. As in the previous compilation, the fractional number of nights with totally clear, partially clear and mostly cloudy skies were determined. The fraction of nights lost due to bad weather was

Aims: We study the equilibrium and stability of twisted magnetic flux tubes with mass flows along the field lines. Then, we focus on the stability and oscillatory modes of magnetic tubes with uniform twist B0 = B0(r/p eϕ + ez) in a zero-β plasma, surrounded by a uniform, purely longitudinal field. Methods: First we investigate the possible

I report on the discovery of two faint (~26.8 R mag arcsec-2) tidal tails around the shell elliptical galaxy NGC 3656 (Arp 155). This galaxy had previously been interpreted as a case of accretion, or minor merger. The two tidal tails are inconsistent with a minor merger and point instead to a disk-disk major merger origin. NGC 3656 extends Toomre's