We discuss the emission of gravitational radiation produced in encounters of dark matter galactic halos. To this aim we perform a number of numerical simulations of typical galaxy mergers, computing the associated gravitational radiation waveforms as well as the energy released in the processes. Our simulations yield dimensionless gravitational

Bimodality is a common feature of globular cluster (GC) color distributions in galaxies. Although it is well known that the GC system of the Milky Way is bimodal in metallicity, this has yet to be directly demonstrated for an elliptical galaxy. We use Lick index measurements from the literature to derive metallicities for 47 GCs in the giant Virgo

We present observations of the full Stokes vector in a flaring region, taken in the chromospheric He I 10830 Å multiplet. The data were recorded with the new Tenerife Infrared Polarimeter (TIP 2) at the German Vacuum Tower Telescope (VTT) during May 2005. The He profiles during the flare are extraordinary, showing extremely broad Stokes I

Aims:We study two dimensional Fabry-Perot interferometric observations of the nearby face-on late-type spiral galaxy, NGC 628, in order to analyse the ionized gas component of the interstellar medium. Covering the galaxy out to a radius larger than 12 kpc, and with a spatial sampling of 1.6'', we aim to investigate the large-scale dynamics as well

Cyclic spectroscopic observations of the dark and bright sides of the moon (or earthshine and moonshine) have been carried out in the visible spectral region from several astronomical observatories as Earth rotates. The ratio of the earthshine to moonshine has been analyzed to determine the globally-integrated Earth's albedo during the observations

Using data from two dense array of short period seismometers, we analyse the kinematic properties of volcanic tremor preceding and accompanying the 2004-2005 eruption of Etna Volcano, Italy. Results from slowness analyses indicate the action of at least two distinct sources. The first dominates the pre-eruptive period, and is likely associated with