We present new 10.4 m-GTC/OSIRIS spectroscopic observations of the black hole X-ray binary XTE J1118+480 that confirm the orbital period decay at (dP/dt) = −1.90 ± 0.57 ms yr −1. This corresponds to a period change of −0.88 ± 0.27 μs per orbital cycle. We have also collected observations of the black hole X-ray binary A0620–00 to derive an orbital period derivative of (dP/dt)= −0.60 ± 0.08 ms yr −1 (−0.53 ± 0.07 μs/cycle). Angular momentum losses due to gravitational radiation are unable to explain these large orbital decays in these two short- period black hole binaries. The orbital period

The aim of the project is to contribute to the characterisation of the spectral energy distribution of the coolest brown dwarfs discovered to date, the Y dwarfs.We obtained z-band far-red imaging for six Y dwarfs and a T9+Y0 binary with the OSIRIS (Optical System for Imaging and low Resolution Integrated Spectroscopy) instrument on the 10.4-m Gran Telescopio de Canarias (GTC).We detect five of the seven known Y dwarfs in the z-band, infer theioptical-to-infrared colours, and measure their proper motions. We find a higher dispersion in the z-J and z-H colours of Y0 dwarfs than in T dwarfs

Rotation is thought to drive cyclic magnetic activity in the Sun and Sun-like stars. Stellar dynamos, however, are poorly understood owing to the scarcity of observations of rotation and magnetic fields in stars. Here, inferences are drawn on the internal rotation of a distant Sun-like star by studying its global modes of oscillation. We report asteroseismic constraints imposed on the rotation rate and the inclination of the spin axis of the Sun-like star HD52265, a CoRoT prime target known to host a planetary companion. These seismic inferences are remarkably consistent with an independent

Supernova remnants are among the most spectacular examples of astrophysical pistons in our cosmic neighborhood. The gas expelled by the supernova explosion is launched with velocities ∼1000 km/s into the ambient, tenuous interstellar medium, producing shocks that excite hydrogen lines. We have used an optical integral-field spectrograph to obtain high-resolution spatial-spectral maps that allow us to study in detail the shocks in the northwestern rim of supernova 1006. The two-component Halpha line is detected at 133 sky locations. Variations in the broad line widths and the broad-to-narrow

Low− and intermediate-mass (0.8 < M < 8 solar mass) stars constitute most of the stars in the Universe and they end their lives with a phase of strong mass loss and thermal pulses (TP) on the Asymptotic Giant Branch (AGB). AGB stars are fundamental to understand the chemical evolution of galaxies because they are one of the main contributors to the chemical enrichment (e.g. C, N, Li, F, and s-process elements) of the interstellar medium where new stars and planets born. In particular, the more massive (>4-5 solar mass) AGB stars experience Hot Bottom Burning (HBB), i.e. proton-capture

As early as 10 Gyr ago, galaxies with more than 10 ^11 M_sun in stars already existed. While most of these  massive galaxies must have subsequently transformed through on-going star formation and mergers with other galaxies, a small fraction (<0.1%) may have survived untouched till today. Searches for such relic galaxies, useful windows to explore the early Universe, have been inconclusive to date: galaxies with masses and sizes like those observed at high redshift (M_*>10 ^11 M_sun; R_e<1.5 kpc) have been found in the local Universe, but their stars are far too young for the galaxy to be a