We present first comparisons between high resolution observations of the quiet photosphere, obtained with the Interferometric BIdimensional Spectrometer (IBIS) in the non-magnetic Fe I 7090.4 Å spectral line, and the synthetic spectrum calculated for a 3D snapshot of a radiation-hydrodynamical simulation of the solar atmosphere. Together with

We present a discussion of efforts to obtain external validation of the estimated atmospheric parameters (Teff, log g, [Fe/H]) obtained from medium-resolution (R = 2000) SDSS spectroscopy and ugriz photometry, which are being employed for both the completed SDSS-I and the ongoing SEGUE survey. The SDSS/SEGUE spectroscopic pipeline makes use of a

The huge star formation events that occur at some galactic centers do not provide enough clues as to their origin, since the morphological signatures of the triggering mechanism are smeared out in the timescale of a few orbital revolutions of the galaxy core. Our high spatial resolution three-dimensional near-infrared spectroscopy for the first

Aims.We present multiwavelength observations of the gamma-ray burst GRB 051028 detected by HETE-2 in order to derive its afterglow emission parameters and to determine the reason for its optical faintness when compared to other events. Methods: .Observations were taken in the optical (2.0 m Himalayan Chandra Telescope, 1.34 m Tautenburg, 4.2 m

We have analyzed archival Hubble Space Telescope Advanced Camera for Surveys images in g and z of the globular cluster (GC) systems of 53 ellipticals in the Virgo Cluster, spanning massive galaxies to dwarf ellipticals (dEs). Several new results emerged. (1) In the giant ellipticals (gEs) M87 and NGC 4649, there is a correlation between luminosity

We have modelled, for the cases of Milky Way and M31, the effects on the galactic discs, of the arrival at high velocity (≥150 km s-1) of giant HI clouds, with masses of up to 108M&sun;. Predictions are compared with the detailed structure of the observed rotation curves for these two galaxies. The model explains the rises and falls observed at