Populations of supersoft X‐ray sources: Novae,tidal disruption,Type Ia supernovae,accretion‐induced collapse,ionization, and intermediatemass black holes?

Observations of hundreds of supersoft X‐ray sources (SSSs) in external galaxies have shed light on the diversity of the class and on the natures of the sources. SSSs are linked to the physics of Type Ia supernovae and accretion‐induced collapse, ultraluminous X‐ray sources and black holes, the ionization of the interstellar medium, and tidal disruption by supermassive black holes. The class of SSSs has an extension to higher luminosities: ultraluminous SSSs have luminosities above 10³⁹ erg s^–1. There is also an extension to higher energies: quasisoft X‐ray sources (QSSs) emit photons with energies above 1 keV, but few or none with energies above 2 keV. Finally, a significant fraction of the SSSs found in external galaxies switch states between observations, becoming either quasisoft or hard. For many systems “supersoft” refers to a temporary state; SSSs are sources, possibly including a variety of fundamentally different system types, that pass through such a state. We review those results derived from extragalactic data and related theoretical work that are most surprising and that suggest directions for future research (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Life-history- and ecosystem-driven variation in composition and residence pattern of seabream species (Perciformes: Sparidae) in two Mediterranean coastal lagoons

Species composition and length-frequency distributions of six sparid fish species were investigated in two central Mediterranean coastal lagoons off the western coast of Italy: Fogliano and Caprolace. In the former, the sparid fauna was dominated by the gilt-head seabream (Sparus aurata), whereas in Caprolace, species composition was more homogeneous across all six species. Size structure varied considerably among species: S. aurata, Diplodus puntazzo and Diplodus vulgaris had a single-cohort structure in both lagoons, whereas in Diplodus annularis and Diplodus sargus at least two cohorts were identified. In Lithognathus mormyrus inter-lagoon variation was detected, with a single-cohort structure in Fogliano and a two-cohort structure in Caprolace. While inter-specific differences can be explained by variation in life-history strategies among species, intra-specific variation in L. mormyrus is likely to be determined by the known differences between the two habitats: Fogliano being a more confined lagoon, and Caprolace more extensively influenced by the sea.     

Extraordinary blowing snow transport events in East Antarctica

In the convergence slope/coastal areas of Antarctica, a large fraction of snow is continuously eroded and exported by wind to the atmosphere and into the ocean. Snow transport observations from instruments and satellite images were acquired at the wind convergence zone of Terra Nova Bay (East Antarctica) throughout 2006 and 2007. Snow transport features are well-distinguished in satellite images and can extend vertically up to 200 m as first-order quantitatively estimated by driftometer sensor FlowCapt?. Maximum snow transportation occurs in the fall and winter seasons. Snow transportation (drift/blowing) was recorded for ~80% of the time, and 20% of time recorded, the flux is >10^?2 kg m^?2 s^?1 with particle density increasing with height. Cumulative snow transportation is ~4 orders of magnitude higher than snow precipitation at the site. An increase in wind speed and transportation (~30%) was observed in 2007, which is in agreement with a reduction in observed snow accumulation. Extensive presence of ablation surface (blue ice and wind crust) upwind and downwind of the measurement site suggest that the combine processes of blowing snow sublimation and snow transport remove up to 50% of the precipitation in the coastal and slope convergence area. These phenomena represent a major negative effect on the snow accumulation, and they are not sufficiently taken into account in studies of surface mass balance. The observed wind-driven ablation explains the inconsistency between atmospheric model precipitation and measured snow accumulation value.     

Faint Lyman-break galaxies as a crucial test for galaxy formation models

It has recently been shown that galaxy formation models within the Λ cold dark matter cosmology predict that, compared to the observed population, small galaxies (with stellar masses  <10¹¹ M_⊙  ) form too early, are too passive since   z ∼ 3  and host too old stellar populations at   z = 0  . We then expect an overproduction of small galaxies at   z ≳ 4  that should be visible as an excess of faint Lyman-break galaxies. To check whether this excess is present, we use the morgana galaxy formation model and grasil spectrophotometric  +  radiative transfer code to generate mock catalogues of deep fields observed with Hubble Space Telescope Advanced Camera for Surveys. We add observational noise and the effect of Lyman α emission, and perform colour–colour selections to identify Lyman-break galaxies. The resulting mock candidates have plausible properties that closely resemble those of observed galaxies. We are able to reproduce the evolution of the bright tail of the luminosity function of Lyman-break galaxies (with a possible underestimate of the number of the brightest i -dropouts), but uncertainties and degeneracies in dust absorption parameters do not allow to give strong constraints to the model. Besides, our model shows a clear excess with respect to observations of faint Lyman-break galaxies, especially of   z ₈₅₀∼ 27 V   -dropouts at   z ∼ 5  . We quantify the properties of these 'excess' galaxies and discuss the implications: these galaxies are hosted in dark matter haloes with circular velocities in excess of 100 km s⁻¹, and their suppression may require a deep rethinking of stellar feedback processes taking place in galaxy formation.     

Diamonds and eclogites of the Jericho kimberlite (Northern Canada)

We studied diamonds and barren and diamondiferous eclogite xenoliths from the Jericho kimberlite (Northern Slave craton). The majority of the diamonds are non-resorbed octahedral crystals, with moderately aggregated N (IaB < 50%, N < 300 ppm) and δ¹³C = −5 to −41‰. The diamonds belong to “eclogitic” (90% of the studied samples), “websteritic” (7%) and “peridotitic” (3%) assemblages. The Jericho diamonds differ from the majority of “eclogitic” diamonds worldwide in magnesian compositions of associated minerals and extremely light C isotopic compositions (δ¹³C = −24 to −41‰). We propose that metasomatism triggered by H₂O fluids may have been involved in the diamond formation. Multiple episodes of the metasomatism and associated melt extraction of various ages are evident in Jericho eclogite xenoliths where primary garnet and clinopyroxene have been recrystallized to more magnesian minerals with higher contents of some incompatible trace elements and to hydrous secondary phases. The model is supported by the general similarity of mineral compositions in diamondiferous eclogites to those in diamond inclusions and to secondary magnesian garnet and clinopyroxene in recrystallized barren eclogites. The ultimate products of the metasomatism could be “websteritic” diamond assemblages sourced from magnesian eclogites. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Tectonic and climatic control on the Late Messinian sedimentary evolution of the Nijar Basin (Betic Cordillera,Southern Spain)

The Late Messinian fill of the Nijar Basin (Betic Cordillera, southeastern Spain) mainly consists of clastic deposits of the Feos Formation that at basin margins rest unconformably above the primary evaporites of the Yesares Formation, the local equivalent of the Mediterranean Lower Gypsum. The Feos Fm. records the upward transition towards non‐marine environments before the abrupt return to fully marine conditions at the base of the Pliocene. The Feos Fm. is clearly two‐phase, with ‘lower’ and ‘upper’ members, which exhibit substantial differences in terms of facies, thickness, depositional trends and cyclical organization. These members record two distinct sedimentary and tectonic stages of Nijar Basin infilling. A high‐resolution, physical‐stratigraphic framework is proposed based on key beds and stratigraphic cyclicity and patterns that differ largely from those of most previously published studies. The predominant influence on stratigraphic cyclicity is interpreted to be precessionally driven climate changes, allowing their correlation to the Late Messinian astronomically calibrated chronostratigraphic framework. Detailed correlations suggest a phase of enhanced tectonic activity, possibly related to the Serrata‐Carboneras strike‐slip fault zone, during the first stage (‘lower’ member), resulting in a strongly articulated topography with structural lows and highs controlling sediment thickness and facies variation. Tectonic activity decreased during the second stage (‘upper’ member), which is characterized by (1) a progressively dampened and homogenized, (2) overall relative base‐level rise and (3) gradual establishment of hypohaline environments. Facies characteristics, overall stacking patterns and depositional trends of the Feos Fm. are analogous with uppermost Messinian successions of the Northern Apennines, Piedmont Basin and Calabria. Despite minor differences related to the local geodynamic setting, these basins experienced a common Late Messinian history that supports the development of a single, large Mediterranean water body characterized by high‐frequency, climatically‐driven changes in sediment flux and base‐level.     

Fatal landslides in Europe

Landslides are a major hazard causing human and large economic losses worldwide. However, the quantification of fatalities and casualties is highly underestimated and incomplete, thus, the estimation of landslide risk is rather ambitious. Hence, a spatio-temporal distribution of deadly landslides is presented for 27 European countries over the last 20  years (1995–2014). Catastrophic landslides are widely distributed throughout Europe, however, with a great concentration in mountainous areas. In the studied period, a total of 1370 deaths and 784 injuries were reported resulting from 476 landslides. Turkey showed the highest fatalities with 335. An increasing trend of fatal landslides is observed, with a pronounced number of fatalities in the latest period from 2008 to 2014. The latter are mostly triggered by natural extreme events such as storms (i.e., heavy rainfall), earthquakes, and floods and only minor by human activities, such as mining and excavation works. Average economic loss per year in Europe is approximately 4.7 billion Euros. This study serves as baseline information for further risk mapping by integrating deadly landslide locations, local land use data, and will therefore help countries to protect human lives and property.     

Physics and Seismic Modeling for Monitoring CO<Subscript>2</Subscript> Storage

We present a new petro-elastical and numerical-simulation methodology to compute synthetic seismograms for reservoirs subject to CO₂ sequestration. The petro-elastical equations model the seismic properties of reservoir rocks saturated with CO₂, methane, oil and brine. The gas properties are obtained from the van der Waals equation and we take into account the absorption of gas by oil and brine, as a function of the in situ pore pressure and temperature. The dry-rock bulk and shear moduli can be obtained either by calibration from real data or by using rock-physics models based on the Hertz-Mindlin and Hashin-Shtrikman theories. Mesoscopic attenuation due to fluids effects is quantified by using White's model of patchy saturation, and the wet-rock velocities are calculated with Gassmann equations by using an effective fluid modulus to describe the velocities predicted by White's model. The simulations are performed with a poro-viscoelastic modeling code based on Biot's theory, where viscoelasticity is described by generalizing the solid/fluid coupling modulus to a relaxation function. Using the pseudo-spectral method, which allows general material variability, a complete and accurate characterization of the reservoir can be obtained. A simulation, that considers the Utsira sand of the North Sea, illustrates the methodology.     

Dependency of geodynamic parameters on the GNSS constellation

Significant differences in time series of geodynamic parameters determined with different Global Navigation Satellite Systems (GNSS) exist and are only partially explained. We study whether the different number of orbital planes within a particular GNSS contributes to the observed differences by analyzing time series of geocenter coordinates (GCCs) and pole coordinates estimated from several real and virtual GNSS constellations: GPS, GLONASS, a combined GPS/GLONASS constellation, and two virtual GPS sub-systems, which are obtained by splitting up the original GPS constellation into two groups of three orbital planes each. The computed constellation-specific GCCs and pole coordinates are analyzed for systematic differences, and their spectral behavior and formal errors are inspected. We show that the number of orbital planes barely influences the geocenter estimates. GLONASS’ larger inclination and formal errors of the orbits seem to be the main reason for the initially observed differences. A smaller number of orbital planes may lead, however, to degradations in the estimates of the pole coordinates. A clear signal at three cycles per year is visible in the spectra of the differences between our estimates of the pole coordinates and the corresponding IERS 08 C04 values. Combinations of two 3-plane systems, even with similar ascending nodes, reduce this signal. The understanding of the relation between the satellite constellations and the resulting geodynamic parameters is important, because the GNSS currently under development, such as the European Galileo and the medium Earth orbit constellation of the Chinese BeiDou system, also consist of only three orbital planes.     

Recent contamination of mercury in an estuarine environment (Marano lagoon,Northern Adriatic,Italy)

The Marano Lagoon, in the northern Adriatic Sea (Italy), has been affected by mercury (Hg) contamination from industrial and mining activities. It has been estimated that 186,000 kg of Hg were deliberately discharged into the main drainage system (Aussa–Corno River) by a chlor-alkali plant (CAP) from 1940s to 1984. The lagoon has also experienced a secondary long-term Hg input, originated from mining activity in Idrija (Slovenia), due to the supply of fluvial suspended particles carried by the Isonzo River in the Gulf of Trieste. Since local fishing activities are extensively conducted, there is great concern on the risk posed by potentially harmful effects of Hg to the trophic chain.