We present ultradeep radio observations with the Expanded Very Large Array of 4U 1957+11, a Galactic black hole (BH) candidate X-ray binary known to exist in a persistent soft X-ray state. We derive a stringent upper limit of 11.4 μJy beam-1 (3σ) at 5-7 GHz, which provides the most rigorous upper limit to date on the presence of jets in a soft

ELMER is a visible imager and spectrograph for the GTC. ELMER is currently in the final stage of testing (at the PO in La Laguna, Tenerife) previous to be shipped to the Observatorio del Roque de los Muchachos in the island of La Palma, where the GTC telescope is being integrated. ELMER Optics has been exhaustively tested at different steps, from

Tidal interaction governs the redistribution of angular momentum in close binary stars and planetary systems and determines the systems evolution towards the possible equilibrium state. Turbulent friction acting on the equilibrium tide in the convective envelope of low-mass stars is known to have a strong impact on this exchange of angular momentum

We report on the performances measured at room temperature, before and after a cryogenic cooling cycle, of a set of NIR Volume Phase Holographic Gratings (VPHGs) manufactured at the Miguel Hernández University (UMH, Elche, Spain) aimed at their use in astronomical instrumentations. VPHGs are novel optical components which can replace standard ruled

We use deep HST/ACS observations to calculate the star formation history (SFH) of the Cetus dwarf spheroidal (dSph) galaxy. Our photometry reaches below the oldest main-sequence turnoffs, which allows us to estimate the age and duration of the main episode of star formation in Cetus. This is well approximated by a single episode that peaked roughly

We present results of the search for variable stars in a sample of Local Group isolated dwarf galaxies, namely LGS3, IC1613, Cetus, and Tucana, based on very deep HST/ACS data. About 900 variables and candidates have been found in total. Among the confirmed variables, we identified about 700 RR Lyrae stars, 60 Cepheids, and 50 eclipsing binaries