The cosmological numerical simulations tell us that accretion of external metal-poor gas drives star formation (SF) in galaxy disks. One the best pieces of observational evidence supporting this prediction is the existence of low-metallicity star-forming regions in relatively high-metallicity host galaxies. The SF is thought to be fed by metal-poor

The structure and evolution of the Milky Way is imprinted on the kinematics, chemical abundances, and spatial distribution of its constituent stars. In the past, samples of stars in the halo and thick disk have primarily been selected either on the basis of their kinematics (e.g., proper-motion selection), their distinct abundances (e.g., objective

The optical afterglow spectrum of GRB 050401 (at z=2.8992+/-0.0004) shows the presence of a damped Lyα absorber (DLA), with logNHI=22.6+/-0.3. This is the highest column density ever observed in a DLA and is about 5 times larger than the strongest DLA detected so far in any QSO spectrum. From the optical spectrum, we also find a very large Zn

We present an analysis of the optical spectroscopy of 58 stars in the Galactic plane at l=27^° , where a prominent excess in the flux distribution and star counts have been observed in several spectral regions, in particular in the Two-Micron Galactic Survey (TMGS) catalog. The sources were selected from the TMGS to have a K magnitude brighter than

We report on the unprecedented red supergiant (RSG) population of a massive young cluster, located at the base of the Scutum-Crux Galactic arm. We identify candidate cluster RSGs based on 2MASS photometry and medium-resolution spectroscopy. With follow-up high-resolution spectroscopy, we use CO band-head equivalent width and high-precision radial

In this paper, we present meteorological and photometric studies of the Oukaimeden astronomical site in Morocco. The meteorological measurements were obtained over 537 days. The photometric data were measured by both FIP and GONG instruments over 1182 days. We have also analysed the weather parameters at the Observatorio del Roque de los Muchachos