| 1. |
- Tinetti, Giovanna, et al.
(author)
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The EChO science case
- 2015
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In: Experimental astronomy. - : Springer Science and Business Media LLC. - 0922-6435 .- 1572-9508. ; 40:2-3, s. 329-391
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Journal article (peer-reviewed)abstract
- The discovery of almost two thousand exoplanets has revealed an unexpectedly diverse planet population. We see gas giants in few-day orbits, whole multi-planet systems within the orbit of Mercury, and new populations of planets with masses between that of the Earth and Neptune-all unknown in the Solar System. Observations to date have shown that our Solar System is certainly not representative of the general population of planets in our Milky Way. The key science questions that urgently need addressing are therefore: What are exoplanets made of? Why are planets as they are? How do planetary systems work and what causes the exceptional diversity observed as compared to the Solar System? The EChO (Exoplanet Characterisation Observatory) space mission was conceived to take up the challenge to explain this diversity in terms of formation, evolution, internal structure and planet and atmospheric composition. This requires in-depth spectroscopic knowledge of the atmospheres of a large and well-defined planet sample for which precise physical, chemical and dynamical information can be obtained. In order to fulfil this ambitious scientific program, EChO was designed as a dedicated survey mission for transit and eclipse spectroscopy capable of observing a large, diverse and well-defined planet sample within its 4-year mission lifetime. The transit and eclipse spectroscopy method, whereby the signal from the star and planet are differentiated using knowledge of the planetary ephemerides, allows us to measure atmospheric signals from the planet at levels of at least 10(-4) relative to the star. This can only be achieved in conjunction with a carefully designed stable payload and satellite platform. It is also necessary to provide broad instantaneous wavelength coverage to detect as many molecular species as possible, to probe the thermal structure of the planetary atmospheres and to correct for the contaminating effects of the stellar photosphere. This requires wavelength coverage of at least 0.55 to 11 mu m with a goal of covering from 0.4 to 16 mu m. Only modest spectral resolving power is needed, with R similar to 300 for wavelengths less than 5 mu m and R similar to 30 for wavelengths greater than this. The transit spectroscopy technique means that no spatial resolution is required. A telescope collecting area of about 1 m(2) is sufficiently large to achieve the necessary spectro-photometric precision: for the Phase A study a 1.13 m(2) telescope, diffraction limited at 3 mu m has been adopted. Placing the satellite at L2 provides a cold and stable thermal environment as well as a large field of regard to allow efficient time-critical observation of targets randomly distributed over the sky. EChO has been conceived to achieve a single goal: exoplanet spectroscopy. The spectral coverage and signal-to-noise to be achieved by EChO, thanks to its high stability and dedicated design, would be a game changer by allowing atmospheric composition to be measured with unparalleled exactness: at least a factor 10 more precise and a factor 10 to 1000 more accurate than current observations. This would enable the detection of molecular abundances three orders of magnitude lower than currently possible and a fourfold increase from the handful of molecules detected to date. Combining these data with estimates of planetary bulk compositions from accurate measurements of their radii and masses would allow degeneracies associated with planetary interior modelling to be broken, giving unique insight into the interior structure and elemental abundances of these alien worlds. EChO would allow scientists to study exoplanets both as a population and as individuals. The mission can target super-Earths, Neptune-like, and Jupiter-like planets, in the very hot to temperate zones (planet temperatures of 300-3000 K) of F to M-type host stars. The EChO core science would be delivered by a three-tier survey. The EChO Chemical Census: This is a broad survey of a few-hundred exoplanets, which allows us to explore the spectroscopic and chemical diversity of the exoplanet population as a whole. The EChO Origin: This is a deep survey of a subsample of tens of exoplanets for which significantly higher signal to noise and spectral resolution spectra can be obtained to explain the origin of the exoplanet diversity (such as formation mechanisms, chemical processes, atmospheric escape). The EChO Rosetta Stones: This is an ultra-high accuracy survey targeting a subsample of select exoplanets. These will be the bright "benchmark" cases for which a large number of measurements would be taken to explore temporal variations, and to obtain two and three dimensional spatial information on the atmospheric conditions through eclipse-mapping techniques. If EChO were launched today, the exoplanets currently observed are sufficient to provide a large and diverse sample. The Chemical Census survey would consist of > 160 exoplanets with a range of planetary sizes, temperatures, orbital parameters and stellar host properties. Additionally, over the next 10 years, several new ground- and space-based transit photometric surveys and missions will come on-line (e.g. NGTS, CHEOPS, TESS, PLATO), which will specifically focus on finding bright, nearby systems. The current rapid rate of discovery would allow the target list to be further optimised in the years prior to EChO's launch and enable the atmospheric characterisation of hundreds of planets.
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| 2. |
- Wagner, Michelle, et al.
(author)
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ORAMA Project - D6-6 Technical Final Report and Recommendations
- 2019
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Reports (other academic/artistic)abstract
- Securing the sustainable access to and supply of raw materials, and particularly of Critical Raw Materials (CRM), is of high importance for the European economy. Complex primary and secondary resources contain many different raw materials. The inability to easily produce reliable statistics about reserves, resources, stocks, and flows of raw materials limits the understanding of global trends in resource availability and hampers formulation of mineral and waste policies. This ultimately affects supply chain security and strategic decisions by industry. Hence, it is an issue of great concern for the European Commission (EC) and many other stakeholders. The ORAMA project (Optimising quality of information in RAw MAterial data collection across Europe) seeks to contribute to better supply of raw materials by improving the quality of harmonised raw materials data collection and information sharing among the different levels within the European Union (EU). Data collection practices for primary and secondary raw materials (PRM and SRM) face specific challenges in EU Member States (MS). For PRM data, the main concerns are related to data availability, geographical coverage, accessibility, harmonisation, interoperability, quality, and thematic coverage. The reporting of primary mineral resources and reserves statistics is currently carried out by a wide variety of systems, standards or codes which are not directly comparable. Hence, it is currently impossible to produce reliable pan-European figures for resources for any mineral commodity. ORAMA addresses these issues by recommending a single standard for reporting of resource data, the United Nations Framework Classification (UNFC), a framework for reporting mineral resource data developed by the UN. To enable and encourage data providers to adopt this standard for European PRM data, the ORAMA project has developed resources in the form of a range of training materials and good practice examples. The ORAMA project demonstrates that the analysis of various classifications and reporting systems that sit within the INSPIRE (Infrastructure for Spatial Information in the European Community) concept and data services, are not opposing but rather integral elements of the proper European level data collection and production of information for PRM and SRM. The use of UNFC/UNRMS (United Nations Resource Management System) in the framework of the INSPIRE compliant data service can significantly contribute to sustainable resource management taking into account not only geological knowledge and raw materials potential but also environmental and social issues, based on using the national/regional legislative elements for exploration and exploitation as well. In the case of SRM, the challenges are somewhat different. Regarding mining waste (MIN), the lack of information on deposit characteristics (composition, volumes, and suitable processing technology) is a huge barrier in the identification of recovery potential of the valuable materials that remain in the waste. Furthermore, the lack of a single reporting standard commonly accepted at EU level has created a dispersion of existing information in various systems and project deliverables. In the case of electrical and electronic equipment (EEE) and batteries, beyond the lack of harmonisation, substantial data gaps exist for the market inputs, materials consumption and stocks, and for waste electrical and electronic equipment (WEEE) for unaccounted flows ending up being scavenged, metal scrap and export channels. For vehicles, huge amounts of data, both on stocks and flows and on composition, are systematically collected by authorities and the manufacturing industry, but are only publicly available in a somewhat too aggregated form (placed on market (POM), stock, waste flows) or not at all (composition data). Even when collected, the reporting of the composition of these flows on a product, component and materials level are currently poorly described across all MS, and when actually ending up in recycling processes, the recovery efficiency for all elements and CRMs, in particular, is disappointing. In order to improve the data collection and reporting practices for SRM a structured review and inventory were made followed by a data gap analysis which resulted in the developments of recommendations and subsequently the selection of 6 case studies. The SRM case studies tackle the main data gaps encountered in the analysis and developed tools that will enable the improvement and harmonisation of collection and reporting practices in MS, treatment facilities, data providers, academia among others. The ORAMA project recommends to establish more structured and continuous funding for realising and maintaining a European data infrastructure for tracking both PRM and SRM. The current project-by-project based financing is insufficient and not sustainable to properly track and understand Europe’s strengths and weaknesses in the early resource intensive stages of global supply chains.
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| 3. |
- Brown, Paul L., et al.
(author)
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On the solubility of radium and other alkaline earth sulfate and carbonate phases at elevated temperature
- 2019
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In: Geochimica et Cosmochimica Acta. - : Elsevier BV. - 0016-7037 .- 0046-564X. ; 255, s. 88-104
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Journal article (peer-reviewed)abstract
- Solubility constant data for alkaline earth sulfate and carbonate phases were collated. Thermodynamic data for these phases were determined by assuming that the solubility (log K-s) of each phase is a function of the inverse of absolute temperature with a constant, but non-zero, heat capacity change. The solubility for all phases, both sulfate and carbonate, exhibits a maximum at a particular temperature, with the temperature at which the maximum solubility occurs increasing as the alkaline earth metals become heavier (for both sulfate and carbonate phases). The heat capacity change was found to be a quadratic function of the square root of the ionic radius. The enthalpy of reaction, at 25 degrees C, is related to the temperature at which the maximum solubility occurs. Combination of these behaviours allows the solubility of the alkaline earth sulfate and carbonate phases to be determined across a temperature range of 0 to 300 degrees C. These relationships allow solubility data to be determined for the same temperature range for radium sulfate and carbonate for which very few literature data are available, particularly for radium carbonate.
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| 4. |
- Dale, Virginia H., et al.
(author)
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Status and prospects for renewable energy using wood pellets from the southeastern United States
- 2017
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In: Global Change Biology Bioenergy. - : Wiley-Blackwell. - 1757-1693 .- 1757-1707. ; 9:8, s. 1296-1305
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Journal article (peer-reviewed)abstract
- The ongoing debate about costs and benefits of wood-pellet based bioenergy production in the southeastern United States (SE USA) requires an understanding of the science and context influencing market decisions associated with its sustainability. Production of pellets has garnered much attention as US exports have grown from negligible amounts in the early 2000s to 4.6 million metric tonnes in 2015. Currently, 98% of these pellet exports are shipped to Europe to displace coal in power plants. We ask, 'How is the production of wood pellets in the SE USA affecting forest systems and the ecosystem services they provide?' To address this question, we review current forest conditions and the status of the wood products industry, how pellet production affects ecosystem services and biodiversity, and what methods are in place to monitor changes and protect vulnerable systems. Scientific studies provide evidence that wood pellets in the SE USA are a fraction of total forestry operations and can be produced while maintaining or improving forest ecosystem services. Ecosystem services are protected by the requirement to utilize loggers trained to apply scientifically based best management practices in planning and implementing harvest for the export market. Bioenergy markets supplement incomes to private rural landholders and provide an incentive for forest management practices that simultaneously benefit water quality and wildlife and reduce risk of fire and insect outbreaks. Bioenergy also increases the value of forest land to landowners, thereby decreasing likelihood of conversion to nonforest uses. Monitoring and evaluation are essential to verify that regulations and good practices are achieving goals and to enable timely responses if problems arise. Conducting rigorous research to understand how conditions change in response to management choices requires baseline data, monitoring, and appropriate reference scenarios. Long-term monitoring data on forest conditions should be publicly accessible and utilized to inform adaptive management.
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| 5. |
- Katz, D., et al.
(author)
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Gaia Data Release 2 Mapping the Milky Way disc kinematics
- 2018
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In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 616
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Journal article (peer-reviewed)abstract
- Context. The second Gaia data release (Gaia DR2) contains high-precision positions, parallaxes, and proper motions for 1.3 billion sources as well as line-of-sight velocities for 7.2 million stars brighter than G(RVS) = 12 mag. Both samples provide a full sky coverage. Aims. To illustrate the potential of Gaia DR2, we provide a first look at the kinematics of the Milky Way disc, within a radius of several kiloparsecs around the Sun. Methods. We benefit for the first time from a sample of 6.4 million F-G-K stars with full 6D phase-space coordinates, precise parallaxes (sigma((omega) over bar)/(omega) over bar <= 20%), and precise Galactic cylindrical velocities (median uncertainties of 0.9-1.4 km s(-1) and 20% of the stars with uncertainties smaller than 1 km s(-1) on all three components). From this sample, we extracted a sub-sample of 3.2 million giant stars to map the velocity field of the Galactic disc from similar to 5 kpc to similar to 13 kpc from the Galactic centre and up to 2 kpc above and below the plane. We also study the distribution of 0.3 million solar neighbourhood stars (r < 200 pc), with median velocity uncertainties of 0.4 km s(-1), in velocity space and use the full sample to examine how the over-densities evolve in more distant regions. Results. Gaia DR2 allows us to draw 3D maps of the Galactocentric median velocities and velocity dispersions with unprecedented accuracy, precision, and spatial resolution. The maps show the complexity and richness of the velocity field of the galactic disc. We observe streaming motions in all the components of the velocities as well as patterns in the velocity dispersions. For example, we confirm the previously reported negative and positive galactocentric radial velocity gradients in the inner and outer disc, respectively. Here, we see them as part of a non-axisymmetric kinematic oscillation, and we map its azimuthal and vertical behaviour. We also witness a new global arrangement of stars in the velocity plane of the solar neighbourhood and in distant regions in which stars are organised in thin substructures with the shape of circular arches that are oriented approximately along the horizontal direction in the U - V plane. Moreover, in distant regions, we see variations in the velocity substructures more clearly than ever before, in particular, variations in the velocity of the Hercules stream. Conclusions. Gaia DR2 provides the largest existing full 6D phase-space coordinates catalogue. It also vastly increases the number of available distances and transverse velocities with respect to Gaia DR1. Gaia DR2 offers a great wealth of information on the Milky Way and reveals clear non-axisymmetric kinematic signatures within the Galactic disc, for instance. It is now up to the astronomical community to explore its full potential.
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| 6. |
- Spoto, F., et al.
(author)
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Gaia Data Release 2 : Observations of solar system objects
- 2018
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In: Astronomy and Astrophysics. - : EDP SCIENCES S A. - 0004-6361 .- 1432-0746. ; 616
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Journal article (peer-reviewed)abstract
- Context: The Gaia spacecraft of the European Space Agency (ESA) has been securing observations of solar system objects (SSOs) since the beginning of its operations. Data Release 2 (DR2) contains the observations of a selected sample of 14,099 SSOs. These asteroids have been already identified and have been numbered by the Minor Planet Center repository. Positions are provided for each Gaia observation at CCD level. As additional information, complementary to astrometry, the apparent brightness of SSOs in the unfiltered G band is also provided for selected observations.Aims: We explain the processing of SSO data, and describe the criteria we used to select the sample published in Gaia DR2. We then explore the data set to assess its quality.Methods: To exploit the main data product for the solar system in Gaia DR2, which is the epoch astrometry of asteroids, it is necessary to take into account the unusual properties of the uncertainty, as the position information is nearly one-dimensional. When this aspect is handled appropriately, an orbit fit can be obtained with post-fit residuals that are overall consistent with the a-priori error model that was used to define individual values of the astrometric uncertainty. The role of both random and systematic errors is described. The distribution of residuals allowed us to identify possible contaminants in the data set (such as stars). Photometry in the G band was compared to computed values from reference asteroid shapes and to the flux registered at the corresponding epochs by the red and blue photometers (RP and BP).Results: The overall astrometric performance is close to the expectations, with an optimal range of brightness G similar to 12 - 17. In this range, the typical transit-level accuracy is well below 1 mas. For fainter asteroids, the growing photon noise deteriorates the performance. Asteroids brighter than G similar to 12 are affected by a lower performance of the processing of their signals. The dramatic improvement brought by Gaia DR2 astrometry of SSOs is demonstrated by comparisons to the archive data and by preliminary tests on the detection of subtle non-gravitational effects.
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