We report on the X-ray aperiodic timing analysis of two accreting millisecond pulsars: XTE J1807-294 and IGR J00291+5934. On the one hand, we discovered in XTE J1807-294 seven pairs of simultaneous kilohertz quasi-periodic oscillations (kHz QPOs) separated in frequency by nearly the spin frequency of the neutron star. This confirms the suspected

Numerous spectroscopic studies have shown that stars with giant planets are particularly metal-rich when compared with field stars in the solar neighbourhood. I will review the most recent results concerning the study of the chemical abundances of planet-host stars and will present distributions for several elements, including those of alpha and

Recent high-resolution imaging observations with Chandra have unveiled a striking similarity between the Narrow Line Region (NLR) and the diffuse soft (0.1-keV) emission-line dominated X-ray morphologies in a number of obscured Active Galactic Nuclei (AGN) on scales as large as 0.1-2kpc (Bianchi et al., 2006, A&, 448, 499). This discovery suggests

Context: Large surveys such as the Sloan Digital Sky Survey have made large amounts of spectroscopic and photometric data of galaxies available, thereby providing important information for studying galaxy evolution in dense environments. Aims: We have selected a sample of 88 nearby (z 0.1) galaxy clusters from the SDSS-DR4 with redshift

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Evolutionary synthesis models (ESM) have been extensively used to obtain the star formation history in galaxies by means of SED fitting. Implicit in this use of ESM is that (a) for given evolutionary parameters, the shape of the SED is fixed whatever the size of the observed cluster (b) all regions of the observed SED have the same weight in the