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Garching bei Munchen, Germany

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. Source

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. Source

Emsellem E.,European Southern Observatory | Emsellem E.,Ecole Normale Superieure de Lyon
Monthly Notices of the Royal Astronomical Society | Year: 2013

A recent claim has been made by van den Bosch et al. that the fast-rotator galaxy NGC 1277 hosts an overmassive black hole with a mass (1.7 × 10 10 MȮ larger than half its (central) stellar spheroid mass. We revisit this claim here by examining the predictions from simple dynamical realizations based on new multi-Gaussian expansion (MGE) models of NGC 1277, using the same inclination i - 75°, and constant mass-to-light ratios. We present realizations which fit well the observed photometry taking into account an approximation for the extinction due to the central dust ring. The mass-to-light ratio M/L is fixed following scaling relations which predict a Salpeter-like initial mass function for such a luminous early-type fast rotator, 60 per cent higher than the one of the previously derived best-fitting model. A model without a black hole provides a surprisingly good fit of the observed kinematics outside the unresolved central region, but not, as expected, of the central dispersion and Gauss-Hermite h4 values. A model with a black hole mass of 5 × 109 MȮ allows us to fit the central dispersion profile, consistently with models of the same mass and M/L in van den Bosch et al. It departs from the central h4 values by only about twice the given uncertainty. A slightly varying M/L or the addition of high-velocity stars in the central spatially unresolved region would further lower the need for a very massive black hole in the central region of NGC 1277. These results do not, by themselves, rule out the presence of a presumed overmassive black hole at the centre of NGC 1277. However, they lead us to advocate the use of 3ρ (as opposed to 1ρ) confidence intervals for derived MBH as better, more conservative, guidelines for such studies. We also caution for the use of ill-defined spheroidal components as an input for scaling relations, and emphasize the fact that a MBH in the range 2-5 × 109 MȮ would represent less than 5 per cent of the spheroid bulge-like mass of our models and less than 2.5 percent of its total stellar mass. This would make the black hole in NGC 1277 consistent or just twice as large as what a recent version of the M BH-ρ predicts, well within the observed scatter. We examine the impact of the presence of an inner bar by running simulations from the same MGE model but with extreme anisotropies. An inner small (600 pc diameter) bar forms, and an end-on view does get closer to fitting the central dispersion profile (and fits the h3 amplitude) without the need for a central dark mass, while adding a black hole of 2.5 × 109 MȮ, in line with the prediction from scaling relations, allows us to fit the dispersion peak and h3 profiles. Both models, however, still fail to fit the central h4 value (overpredicting the mean velocity). The claimed large mass of the presumed black hole therefore mostly relies on the measured positive high central h4 (at high dispersion), which can be associated with broad wings in the line-of-sight velocity distribution (high-velocity stars). This emphasizes the need to go beyond medium-resolution long-slit kinematics, with e.g. high-resolution integral-field spectroscopic data. In the specific case of NGC 1277, molecular or ionized gas kinematics (if present) within the central arcsecond (or at large scale) may provide a strong discriminant between these various models. We finally briefly discuss the fact that NGC 1277 resembles a scaled-up version of e.g. NGC 4342, another nearly edge-on fast rotator with a potentially large (but not overmassive) black hole. © 2013 The Author. Source

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. Source

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. Source

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