The European Southern Observatory is a 16-nation intergovernmental research organisation for astronomy. Created in 1962, ESO has provided astronomers with state-of-the-art research facilities and access to the southern sky. The organisation employs about 730 staff members and receives annual member state contributions of approximately €131 million. Its observatories are located in northern Chile.ESO has built and operated some of the largest and most technologically-advanced telescopes. These include the New Technology Telescope, an early pioneer in the use of active optics, and the Very Large Telescope , which consists of four individual telescopes, each with a primary mirror 8.2 metre across, and four smaller auxiliary telescopes. The Atacama Large Millimeter Array observes the universe in the millimetre and submillimetre wavelength ranges, and is the world's largest ground-based astronomy project to date. It was completed in March 2013 in an international collaboration by Europe , North America, East Asia and Chile.Currently under construction is the European Extremely Large Telescope. It will use a 39.3-metre-diameter segmented mirror, and become the world's largest optical reflecting telescope when operational in 2024. Its light-gathering power will allow detailed studies of planets around other stars, the first objects in the universe, supermassive black holes, and the nature and distribution of the dark matter and dark energy which dominate the universe.ESO's observing facilities have made astronomical discoveries and produced several astronomical catalogues. Its findings include the discovery of the most distant gamma-ray burst and evidence for a black hole at the centre of the Milky Way. In 2004, the VLT allowed astronomers to obtain the first picture of an extrasolar planet orbiting a brown dwarf 173 light-years away. The High Accuracy Radial Velocity Planet Searcher instrument installed in another ESO telescope led to the discovery of extrasolar planets, including Gliese 581c—one of the smallest planets seen outside the solar system. Wikipedia.
Cortese L.,European Southern Observatory
Astronomy and Astrophysics | Year: 2012
We used GALEX ultraviolet and WISE 22 μm observations to investigate the current star formation activity of the optically red spirals recently identified as part of the Galaxy Zoo project. These galaxies were accurately selected from the Sloan Digital Sky Survey as pure discs with low or no current star formation activity, representing one of the best optically selected samples of candidate passive spirals. However, we show that these galaxies are not only still forming stars at a significant rate (≈ 1 M ⊙ yr -1) but, more importantly, their star formation activity is not different from that of normal star-forming discs of the same stellar mass (M *≈10 10.2 M ⊙). Indeed, these systems lie on the UV-optical blue sequence, even without any corrections for internal dust attenuation, and they follow the same specific star formation rate vs. stellar mass relation of star-forming galaxies. Our findings clearly show that at high stellar masses, optical colours do not allow to distinguish between actively star-forming and truly quiescent systems. © 2012 ESO.
Padovani P.,European Southern Observatory |
Resconi E.,TU Munich
Monthly Notices of the Royal Astronomical Society | Year: 2014
IceCube has recently reported the discovery of high-energy neutrinos of astrophysical origin, opening up the PeV (1015 eV) sky. Because of their large positional uncertainties, these events have not yet been associated to any astrophysical source. We have found plausible astronomical counterparts in the GeV-TeV bands by looking for sources in the available large area high-energy γ-ray catalogues within the error circles of the IceCube events. We then built the spectral energy distribution of these sources and compared it with the energy and flux of the corresponding neutrino. Likely counterparts include mostly BL Lacs and two Galactic pulsar wind nebulae. On the one hand many objects, including the starburst galaxy NGC 253 and Centaurus A, despite being spatially coincident with neutrino events, are too weak to be reconciled with the neutrino flux. On the other hand, various GeV powerful objects cannot be assessed as possible counterparts due to their lack of TeV data. The definitive association between high-energy astrophysical neutrinos and our candidates will be significantly helped by new TeV observations, but will be confirmed or disproved only by further IceCube data. Either way, this will have momentous implications for blazar jets, high-energy astrophysics, and cosmic ray and neutrino astronomy. © 2014 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.
Smiljanic R.,European Southern Observatory
Monthly Notices of the Royal Astronomical Society | Year: 2012
Sodium abundances have been determined in a large number of giants of open clusters but conflicting results, ranging from solar values to overabundances of up to five orders of magnitude, have been found. The reasons for this disagreement are not well understood. As these Na overabundances can be the result of deep mixing, their proper understanding has consequences for models of stellar evolution. As discussed in the literature, part of this disagreement comes from the adoption of different corrections for non-local thermodynamic equilibrium (NLTE) effects and from the use of different atomic data for the same set of lines. However, a clear picture of the Na behaviour in giants is still missing. To contribute in this direction, this work presents a careful redetermination of the Na abundances of the Hyades giants, motivated by the recent measurement of their angular diameters. An average of [Na/Fe] =+0.30, in NLTE, has been found. This overabundance can be explained by hydrodynamical models with high initial rotation velocities. This result, and a trend of increasing Na with increasing stellar mass found in a previous work, suggests that there is no strong evidence of Na overabundances in red giants beyond those values expected by evolutionary models of stars with more than ∼2 M ⊙. © 2012 The Author Monthly Notices of the Royal Astronomical Society © 2012 RAS.
Carter J.,European Southern Observatory |
Poulet F.,University Paris - Sud
Nature Geoscience | Year: 2013
The mineralogical diversity preserved on ancient terrains of Mars provides insights into the planet's early geological state and subsequent evolution. The martian crust is predominantly composed of mafic rocks with low silica contents, with the exception of a few localized volcanic sequences that indicate some compositional evolution towards compositions richer in silicate minerals. Anorthosite, which is dominated by the silicate mineral plagioclase, is rare in the Solar System. It is thought to require an evolved magmatic source in which lighter elements have been concentrated. Anorthosite has been observed previously only on Earth within localized continental plutons of intrusive igneous origin, and more widely on the Moon where the anorthositic highland crust is thought to derive from crystallization of a primordial magma ocean. Using near-infrared spectral data obtained by the Mars Reconnaissance Orbiter, we report the detection of iron-bearing plagioclase-rich rocks at eight sites in the southern highlands of Mars with a spectral signature consistent with ferroan anorthosites. The paucity of detections suggests a localized plutonic origin similar to terrestrial anorthosites, although a lunar-like global anorthosite crust on early Mars cannot be entirely excluded. Our detections of anorthositic compositions at several locations on the martian surface suggest that magmatic processes that produce highly evolved melts were active on ancient Mars. © 2013 Macmillan Publishers Limited.
Kennicutt Jr. R.C.,University of Cambridge |
Evans N.J.,University of Texas at Austin |
Evans N.J.,European Southern Observatory
Annual Review of Astronomy and Astrophysics | Year: 2012
We review progress over the past decade in observations of large-scale star formation, with a focus on the interface between extragalactic and Galactic studies. Methods of measuring gas contents and star-formation rates are discussed, and updated prescriptions for calculating star-formation rates are provided. We review relations between star formation and gas on scales ranging from entire galaxies to individual molecular clouds. Copyright © 2012 by Annual Reviews.