OB stars are very active actors shaping their environment and contributing to the chemical and dynamical evolution of their host galaxies. Accurate analyses of massive stars are thus a key ingredient in our interpretation of the light coming from the Milky Way and nearby galaxies. These analyses rely in the use of state-of-the-art model atmospheres

O Vz stars are defined as those O-type stars displaying HeII 4686 absorption line stronger than other He line in the blue spectral region. These stars have been hypothesized on spectroscopic grounds to be O-type stars on or close to the Zero-Age-Main-Sequence (ZAMS), also having weaker winds than normal O V stars. We have tested these hypothesis by

Galactic black hole transients show many interesting phenomena during outburst decays. We present simultaneous X-ray (RXTE, Swift, and INTEGRAL), and optical/near-infrared (O/NIR) observations (SMARTS) of the X-ray transient XTE J1752–223 during its outburst decay in 2010. The multiwavelength observations over 150 days in 2010 cover the transition

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We studied the global and local M-Z relation based on the first data available from the CALIFA survey (150 galaxies). This survey provides integral field spectroscopy of the complete optical extent of each galaxy (up to 2-3 effective radii), with a resolution high enough to separate individual H II regions and/or aggregations. About 3000 individual

We have analyzed new and previously published radial velocity (RV) observations of MARVELS-1, known to have an ostensibly substellar companion in a ~6 day orbit. We find significant (~100 m s–1) residuals to the best-fit model for the companion, and these residuals are naïvely consistent with an interior giant planet with a P = 1.965 days in a