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

En esta tesis presentamos un estudio morfológico, fotométrico y espectroscópico detallado de una muestra de 20 galaxias Wolf-Rayet (WR). Las galaxias WR son un subtipo de las galaxias H II cuyo espectro integrado muestra líneas de emisión propias de estrellas WR, indicando la presencia de una población importante de estrellas masivas y la juventud

The atmosphere of the Sun is being stirred and reshaped continuously through the emergence of magnetized plasma from the convection zone. Magnetic elements coming from the solar interior produce structures in the photosphere, chromosphere and corona in a bewildering range of length and time scales, from the smallest magnetic tubes to the largest