Aims: One of the most striking features predicted by standard models of galaxy formation is the presence of anti-correlations in the matter distribution on large enough scales (r > r_c). Simple arguments show that the location of the length scale r_c, marking the transition from positive to negative correlations, is the same for any class of

We present a chemical abundance analysis based on high resolution UVES spectra of seventeen bright giant stars in the Globular Cluster (GC) M 22. We obtained an average iron abundance of [Fe/H] = -1.76±0.02 (internal errors only) and an α enhancement of 0.36±0.04 (internal errors only). Na and O, and Al and O follow the well known anticorrelations

Context: The knowledge of the initial mass function (IMF) in open clusters constitutes one way of constraining the formation of low-mass stars and brown dwarfs, along with the frequency of multiple systems and the properties of disks. Aims: The aim of the project is to determine the shape of the mass function in the low-mass and substellar regimes

After an outburst that lasted more than 2.3 years (starting around June 12th., 2007; Palmer et al., ATel #1113), the neutron star transient and atoll source 4U 1608-52 has returned to quiescence. The source was last detected by Swift-BAT, RXTE-PCA and RXTE-ASM on September 14th. (~0.006 BAT c/s/cm2), September 19th. (~3.5 mCrab) and October 5th. (

Este trabajo está centrado en el estudio de los brotes de formación estelar (FE) de una muestra de Galaxias Enanas Compactas Azules (BCDs), la interacción de los mismos con el Medio Interestelar (MI) circundante y la historia de la formación estelar reciente en cada objeto. La muestra se compone de nueve Galaxias BCDs pertenecientes a las clases

Esta tesis trata del estudio de los cuásares con líneas de absorción anchas (Broad Absorption Line QSOs, BAL QSOs). Actualmente se desconoce la razón por la que muchos cuásares parecen presentan vientos que pueden ser detectados mediante estas líneas de absorción en una fracción importante de la población de cuásares. Las hipótesis más populares