In the phenomenon of gravitational lensing, predicted by Einstein's General Theory of Relativity, the mass of a galaxy acts on the light of a more distant object, as if it were a huge lens, producing a distorted image with the form of a so-called Einstein ring or multiple images and a magnification of the total flux, allowing to see details which would otherwise be too faint to detect. GTC/OSIRIS spectroscopic observations allowed to discover one of the brightest galaxies in the early Universe, BG1429+1202, located at a redshift of 2.82 (we see it as it was some 2,300 million years after the Big Bang). BG1429+1202 is a Lyman-Alpha Emitting galaxy (LAE) gravitationally lensed by a massive Early Type galaxy close to the line of sight at a redshift of 0.55. Although typical LAEs are faint and not very luminous, BG1429+1202 is not only apparently bright but also intrinsically very luminous after accounting for the lensing magnification, showing indications of massive star formation. This galaxy-scale strong gravitational system was found in the BELLS GALLERY project that analysed around a million and a half spectra of galaxies obtained with the Sloan Telescope, at the Apache Point Observatory in New Mexico (USA), by the BOSS survey, part of the Sloan Digital Sky Survey III.
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Stellar ages are key to several fields of astrophysics such as exoplanet research, galactic-archeology, and of course stellar physics. Obtaining the ages of stars is however not straightforward and requires stellar modeling. The most widely used technique only requires stellar colors or temperature and surface gravity, but the uncertainties are quite large. This technique is most efficient for stars belonging to clusters, as they were born from the same molecular cloud and share the same ages. In the last decades, based on the study of stellar acoustic waves, asteroseismology became the most
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Accretion disks around compact objects are expected to enter an unstable phase at high luminosity. One instability may occur when the radiation pressure generated by accretion modifies the disk viscosity, resulting in the cyclic depletion and refilling of the inner disk on short timescales. Such a scenario, however, has only been quantitatively verified for a single stellar-mass black hole. Although there are hints of these cycles in a few isolated cases, their apparent absence in the variable emission of most bright accreting neutron stars and black holes has been a continuing puzzle. Here
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It is well known that fullerenes – big, complex, and highly resistant carbon molecules with potential applications in nanotechnology – are mostly seen in planetary nebulae (PNe); old dying stars with progenitor masses similar to our Sun. Fullerenes, like C60 and C70, have been detected in PNe whose infrared (IR) spectra are dominated by broad unidentified IR (UIR) plateau emissions. The identification of the chemical species (structure and composition) responsible for such UIR emission widely present in the Universe is a mystery in astrochemistry; although they are believed to be carbon-rich
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