Aims: The Si i 10 827 Å line is commonly used for spectropolarimetric diagnostics of the solar atmosphere. First, we aim at quantifying the sensitivity of the Stokes profiles of this line to non-local thermodynamic equilibrium (NLTE) effects. Second, we aim at facilitating NLTE diagnostics of the Si i 10 827 Å line. To this end, we propose the use

Multi-wavelength CCD photometry over 21 years has been used to produce deep color–magnitude diagrams (CMDs) together with light curves for the variables in the Galactic globular cluster NGC 5824. Twenty-one new cluster RR Lyrae stars are identified, bringing the total to 47, of which 42 have reliable periods determined for the first time. The CMD

CoRoT-9b is one of the rare long-period (P = 95.3 days) transiting giant planets with a measured mass known to date. We present a new analysis of the CoRoT-9 system based on five years of radial-velocity (RV) monitoring with HARPS and three new space-based transits observed with CoRoT and Spitzer. Combining our new data with already published

La espectroscopía es una de las fuentes de información más valiosas de que dispone la astrofísica estelar. La correcta interpretación de los espectros estelares es vital en muchos campos, ya que de ellos se derivan los parámetros fundamentales de las estrellas, su rotación, composición química, velocidad radial, etc. y, a partir de espectros de

The accurate characterization of the physical properties of massive stars in very low-metallicity environments has important implications in our interpretation of the primitive Universe. The first population of stars, which are thought to have been very massive and extremely metal-poor, has been proposed as the responsible source of the re