Interstellar dust plays a crucial role in the evolution of the Universe by assisting the formation of molecules, by triggering the formation of the first low-mass stars, and by absorbing stellar ultraviolet-optical light and subsequently re-emitting it at infrared/millimetre wavelengths. Dust is thought to be produced predominantly in the envelopes of evolved (age >1 Gyr), low-mass stars. This picture has, however, recently been brought into question by the discovery of large masses of dust in the host galaxies of quasars at redshift z > 6, when the age of the Universe was less than 1 Gyr. Theoretical studies, corroborated by observations of nearby supernova remnants, have suggested that supernovae provide a fast and efficient dust formation environment in the early Universe. Here we report infrared observations of a quasar at redshift 6.2, which are used to obtain directly its dust extinction curve. We then show that such a curve is in excellent agreement with supernova dust models. This result demonstrates a supernova origin for dust in this high-redshift quasar, from which we infer that most of the dust at high redshifts probably has the same origin.

We carried out a Bayesian homogeneous determination of the orbital parameters of 231 transiting giant planets (TGPs) that are alone or have distant companions; we employed differential evolution Markov chain Monte Carlo methods to analyse radial-velocity (RV) data from the literature and 782 new high-accuracy RVs obtained with the HARPS-N spectrograph for 45 systems over ∼3 years. Our work yields the largest sample of systems with a transiting giant exoplanet and coherently determined orbital, planetary, and stellar parameters. We found that the orbital parameters of TGPs in non-compact planetary systems are clearly shaped by tides raised by their host stars. Indeed, the most eccentric planets have relatively large orbital separations and/or high mass ratios, as expected from the equilibrium tide theory. This feature would be the outcome of planetary migration from highly eccentric orbits excited by planetplanet scattering, Kozai-Lidov perturbations, or secular chaos. The distribution of α = a/a R , where a and a R are the semi-major axis and the Roche limit, for well-determined circular orbits peaks at 2.5; this agrees with expectations from the high-eccentricity migration (HEM), although it might not be limited to this migration scenario. The few planets of our sample with circular orbits and α > 5 values may have migrated through disc-planet interactions instead of HEM. By comparing circularisation times with stellar ages, we found that hot Jupiters with a < 0.05 au have modified tidal quality factors 10 5 Q p 10 9 , and that stellar Q s 10 6 −10 7 are required to explain the presence of eccentric planets at the same orbital distance. As a by-product of our analysis, we detected a non-zero eccentricity e = 0.104 +0.021 −0.018 for HAT-P-29; we determined that five planets that were previously regarded to be eccentric or to have hints of non-zero eccentricity, namely CoRoT-2b, CoRoT-23b, TrES-3b, HAT-P-23b, and WASP-54b, have circular orbits or undetermined eccentricities; we unveiled curvatures caused by distant companions in the RV time series of HAT-P-2, HAT-P-22, and HAT-P-29; we significantly improved the orbital parameters of the long-period planet HAT-P-17c; and we revised the planetary parameters of CoRoT-1b, which turned out to be considerably more inflated than previously found. of giant planets are still open questions. Among these are the migration of hot Jupiters, the origin of the frequently observed spin-orbit misalignments, and the architecture of planetary systems with closein giant planets. These planets are thought to be formed beyond the water-ice line (a 1−3 au) in the protoplanetary disc, where solid material is abundant because of ice condensation, Article published by EDP Sciences A107, page 1 of 16 A&A 602, A107 (2017)

We investigate the metallicity of the broad line region (BLR) of a sample of 30 quasars in the redshift range 4 < z < 6.4, by using near-IR and optical spectra. We focus on the ratio of the broad lines (SiIV1397+OIV]1402)/CIV1549, which is a good metallicity tracer of the BLR. We find that the metallicity of the BLR is very high even in QSOs at z ∼ 6. The inferred metallicity of the BLR gas is so high (several times solar) that metal ejection or mixing with lower metallicity gas in the host galaxy is required to match the metallicities observed in local massive galaxies. On average, the observed metallicity changes neither among quasars in the observed redshift range 4 < z < 6.4, nor when compared with quasars at lower redshifts. We show that the apparent lack of metallicity evolution is a likely consequence of both the black hole-galaxy co-evolution and of selection effects. The data also suggest a lack of evolution in the carbon abundance, even among z > 6 quasars. The latter result is puzzling, since the minimum enrichment timescale of carbon is about 1 Gyr, i.e. longer than the age of the universe at z ∼ 6.

Context. The population of known large trans-neptunian objects (TNOs) is growing very fast and the knowledge of their physical properties is a key issue to understand the origin and evolution of the Solar System. Aims. In this paper we studied the surface composition of the recently discovered TNO 2005 FY 9 , one of the largest known TNOs (∼0.7 times the diameter of Pluto, i.e. 1600 km, if the albedo is similar, or 3100-1550 km in diameter assuming an albedo range 0.2 < p V < 0.8).Methods. We report visible and near infrared spectra covering the 0.35-2.5 µm spectral range, obtained with the 4.2 m William Herschel Telescope and the Italian 3.58 m Telescopio Nazionale Galileo at "El Roque de los Muchachos" Observatory (La Palma, Spain). Results. The spectrum of this large TNO is similar to that of Pluto, with an infrared region dominated by very prominent absorptions bands formed in solid CH 4 . At wavelengths shorter than 0.6 µm, the spectrum is almost featureless and red. The red color most likely indicates the presence of complex organics, as has been hypothesized for Pluto and many other TNOs. The icy-CH 4 bands in this new giant TNO are significantly stronger than those of Pluto, implying that methane could be even more abundant on its surface. The existence of a volatile such as methane on the surface of 2005 FY 9 , likely accompanied by N 2 and CO ices, coupled with its large size, make this Pluto-like TNO an excellent candidate to have an atmosphere comparable to Pluto's.

209458b formed far from its present location and subsequently migrated inwards 11,13 . Other hot Jupiters may also show a richer chemistry than has been previously found, which would bring into question the frequently made assumption that they have solar-like and oxygen-rich compositions.We observed four transits of HD 209458b, the archetype of transiting hot Jupiters, with the near-infrared echelle spectrograph GIANO-B 14 , mounted at the 3.6-m Telescopio Nazionale Galileo located in La Palma, Spain. The transits happened on