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- ItemMineral dust in Central Asia: Combining lidar and other measurements during the Central Asian dust experiment (CADEX)(Les Ulis : EDP Sciences, 2018) Althausen, Dietrich; Hofer, Julian; Abdullaev, Sabur; Makhmudov, Abduvosit; Baars, Holger; Engelmann, Ronny; Wadinga Fomba, Khanneh; Müller, Konrad; Schettler, Georg; Klüser, Lars; Kandler, Konrad; Nicolae, D.; Makoto, A.; Vassilis, A.; Balis, D.; Behrendt, A.; Comeron, A.; Gibert, F.; Landulfo, E.; McCormick, M.P.; Senff, C.; Veselovskii, I.; Wandinger, U.Mineral dust needs to be characterized comprehensively since it contributes to the climate change in Tajikistan / Central Asia. Lidar results from the measurements of mineral dust during CADEX are compared with results of sun photometer measurements, satellite-based measurements, and chemical analysis of ground samples. Although the dust is often advected from far-range sources, it impacts on the local conditions considerably.
- ItemLong-time resistivity monitoring of a freshwater/saltwater transition zone using the vertical electrode system SAMOS(Les Ulis : EDP Sciences, 2018) Grinat, Michael; Epping, Dieter; Meyer, Robert; Szymkiewicz, Adam; Sadurski, A.; Jaworska-Szulc, B.In September 2009 two newly developed vertical electrode systems were installed in boreholes in the water catchment areas Waterdelle and Ostland at the North Sea island Borkum to monitor possible changes of the transition zone between the freshwater lens and the underlying saltwater. The vertical electrode systems, which were both installed between 44 m and 65 m below ground level, are used for geoelectrical multi-electrode measurements carried out automatically several times per day; the measurements are still ongoing. The whole system consisting of a vertical electrode system in a borehole and the measuring unit at ground level is called SAMOS (Saltwater Monitoring System). At both locations the data show a clear resistivity decrease that indicates the transition zone between freshwater and saltwater. The depth of the transition zone as well as the kind of resistivity decrease is very stable since 2010. Temporal changes are visible if single depths are considered. In 2015 Miriam Ibenthal used a vertical 2D density-dependent groundwater flow model to explain the long-term resistivity measurements and showed that the temporal changes at CLIWAT 2 (Ostland) could be explained by variations of the groundwater level, changing groundwater recharge rates and changing pumping rates of the nearby located drinking water supply wells.
- ItemSaltwater intrusion under climate change in North-Western Germany - mapping, modelling and management approaches in the projects TOPSOIL and go-CAM(Les Ulis : EDP Sciences, 2018) Wiederhold, Helga; Scheer, Wolfgang; Kirsch, Reinhard; Azizur Rahman, M.; Ronczka, Mathias; Szymkiewicz, Adam; Sadurski, A.; Jaworska-Szulc, B.Climate change will result in rising sea level and, at least for the North Sea region, in rising groundwater table. This leads to a new balance at the fresh–saline groundwater boundary and a new distribution of saltwater intrusions with strong regional differentiations. These effects are investigated in several research projects funded by the European Union and the German Federal Ministry of Education and Research (BMBF). Objectives and some results from the projects TOPSOIL and go-CAM are presented in this poster.
- ItemTwo new magnetic cataclysmic variables discovered in the 3XMM catalogue(Les Ulis : EDP Sciences, 2018) Webb, N.A.; Schwope, A.; Zolotukhin, I.; Lin, D.; Rosen, S.R.Context. X-ray catalogues provide a wealth of information on many source types, ranging from compact objects to galaxies, clusters of galaxies, stars, and even planets. Thanks to the huge volume of X-ray sources provided in the 3XMM catalogue, along with many source specific products, many new examples from rare classes of sources can be identified. Aims. Through visualising spectra and lightcurves from about 80 observations included in the incremental part of the 3XMM catalogue, 3XMM-DR5, as part of the quality control of the catalogue, we identified two new X-ray sources, 3XMM J183333.1+225136 and 3XMM J184916.1+652943, that were highly variable. This work aims to investigate their nature. Methods. Through simple model fitting of the X-ray spectra and analysis of the X-ray lightcurves of 3XMM J183333.1+225136 and 3XMM J184916.1+652943, along with complementary photometry from the XMM-Newton Optical Monitor, Pan-STARRS and the Stella/WiFSIP and Large Binocular Telescope (LBT) spectra, we suggest that the two sources might be magnetic cataclysmic variables (CVs) of the polar type and we determine some of their properties. Results. Both CVs have very hard spectra, showing no soft excess. They are both situated in the local neighbourhood, located within ∼1 kpc. 3XMM J183333.1+225136 has an orbital period of 2.15 h. It shows features in the lightcurve that may be a total eclipse of the white dwarf. 3XMM J184916.1+652943 has an orbital period of 1.6 h. Given that only a small sky area was searched to identify these CVs, future sensitive all sky surveys such as the eROSITA project should be very successful at uncovering large numbers of such sources.
- ItemMUSE crowded field 3D spectroscopy in NGC 300 : I. First results from central fields(Les Ulis : EDP Sciences, 2018) Roth, Martin M.; Sandin, Christer; Kamann, Sebastian; Husser, Tim-Oliver; Weilbacher, Peter M.; Monreal-Ibero, Ana; Bacon, Roland; den Brok, Mark; Dreizler, Stefan; Kelz, Andreas; Marino, Raffaella Anna; Steinmetz, MatthiasAims. As a new approach to the study of resolved stellar populations in nearby galaxies, our goal is to demonstrate with a pilot study in NGC 300 that integral field spectroscopy with high spatial resolution and excellent seeing conditions reaches an unprecedented depth in severely crowded fields. Methods. Observations by MUSE with seven pointings in NGC 300 have resulted in data cubes that are analyzed in four ways: (1) Point spread function-fitting 3D spectroscopy with PampelMUSE, as already successfully pioneered in globular clusters, yields de-blended spectra of individually distinguishable stars, thus providing a complete inventory of blue and red supergiants, and asymptotic giant branch (AGB) stars of type M and C. The technique is also applicable to emission line point sources and provides samples of planetary nebulae (PNe) that are complete down to m5007 = 28. (2) Pseudo-monochromatic images, created at the wavelengths of the most important emission lines and corrected for continuum light with the P3D visualization tool, provide maps of HâII regions, supernova remnants (SNR), and the diffuse interstellar medium (ISM) at a high level of sensitivity, where also faint point sources stand out and allow for the discovery of PNe, Wolf-Rayet (WR) stars, etc. (3) The use of the P3D line-fitting tool yields emission line fluxes, surface brightness, and kinematic information for gaseous objects, corrected for absorption line profiles of the underlying stellar population in the case of Hα. (4) Visual inspection of the data cubes by browsing through the row-stacked spectra image in P3D is demonstrated to be efficient for data mining and the discovery of background galaxies and unusual objects. Results. We present a catalog of luminous stars, rare stars such as WR, and other emission line stars, carbon stars, symbiotic star candidates, PNe, HâII regions, SNR, giant shells, peculiar diffuse and filamentary emission line objects, and background galaxies, along with their spectra. Conclusions. The technique of crowded-field 3D spectroscopy, using the PampelMUSE code, is capable of deblending individual bright stars, the unresolved background of faint stars, gaseous nebulae, and the diffuse component of the ISM, resulting in unprecedented legacy value for observations of nearby galaxies with MUSE.
- ItemGaia Data Release 2 : Processing the spectroscopic data(Les Ulis : EDP Sciences, 2018) Sartoretti, P.; Katz, D.; Cropper, M.; Panuzzo, P.; Seabroke, G. M.; Viala, Y.; Benson, K.; Blomme, R.; Jasniewicz, G.; Jean-Antoine, A.; Huckle, H.; Smith, M.; Baker, S.; Crifo, F.; Damerdji, Y.; David, M.; Dolding, C.; Frémat, Y.; Gosset, E.; Guerrier, A.; Guy, L. P.; Haigron, R.; Janßen, K.; Marchal, O.; Plum, G.; Soubiran, C.; Thévenin, F.; Ajaj, M.; Allende Prieto, C.; Babusiaux, C.; Boudreault, S.; Chemin, L.; Delle Luche, C.; Fabre, C.; Gueguen, A.; Hambly, N. C.; Lasne, Y.; Meynadier, F.; Pailler, F.; Panem, C.; Riclet, F.; Royer, F.; Tauran, G.; Zurbach, C.; Zwitter, T.; Arenou, F.; Gomez, A.; Lemaitre, V.; Leclerc, N.; Morel, T.; Munari, U.; Turon, C.; Žerjal, M.Context. The Gaia Data Release 2 (DR2 ) contains the first release of radial velocities complementing the kinematic data of a sample of about 7 million relatively bright, late-type stars. Aims. This paper provides a detailed description of the Gaia spectroscopic data processing pipeline, and of the approach adopted to derive the radial velocities presented in DR2 . Methods. The pipeline must perform four main tasks: (i) clean and reduce the spectra observed with the Radial Velocity Spectrometer (RVS); (ii) calibrate the RVS instrument, including wavelength, straylight, line-spread function, bias non-uniformity, and photometric zeropoint; (iii) extract the radial velocities; and (iv) verify the accuracy and precision of the results. The radial velocity of a star is obtained through a fit of the RVS spectrum relative to an appropriate synthetic template spectrum. An additional task of the spectroscopic pipeline was to provide first-order estimates of the stellar atmospheric parameters required to select such template spectra. We describe the pipeline features and present the detailed calibration algorithms and software solutions we used to produce the radial velocities published in DR2 . Results. The spectroscopic processing pipeline produced median radial velocities for Gaia stars with narrow-band near-IR magnitude GRVS ≤ 12 (i.e. brighter than V ∼ 13). Stars identified as double-lined spectroscopic binaries were removed from the pipeline, while variable stars, single-lined, and non-detected double-lined spectroscopic binaries were treated as single stars. The scatter in radial velocity among different observations of a same star, also published in Gaia DR2, provides information about radial velocity variability. For the hottest (Te≥ 7000 K) and coolest (Te≤ 3500 K) stars, the accuracy and precision of the stellar parameter estimates are not sufficient to allow selection of appropriate templates. The radial velocities obtained for these stars were removed from DR2 . The pipeline also provides a first-order estimate of the performance obtained. The overall accuracy of radial velocity measurements is around ∼200-300 m s-1, and the overall precision is ∼1 km s-1; it reaches ∼200 m s-1 for the brightest stars.
- ItemSynthetic simulations of the extragalactic sky seen by eROSITA : I. Pre-launch selection functions from Monte-Carlo simulations(Les Ulis : EDP Sciences, 2018) Clerc, N.; Ramos-Ceja, M.E.; Ridl, J.; Lamer, G.; Brunner, H.; Hofmann, F.; Comparat, J.; Pacaud, F.; Käfer, F.; Reiprich, T.H.; Merloni, A.; Schmid, C.; Brand, T.; Wilms, J.; Friedrich, P.; Finoguenov, A.; Dauser, T.; Kreykenbohm, I.Context. Studies of galaxy clusters provide stringent constraints on models of structure formation. Provided that selection effects are under control, large X-ray surveys are well suited to derive cosmological parameters, in particular those governing the dark energy equation of state. Aims. We forecast the capabilities of the all-sky eROSITA (extended ROentgen Survey with an Imaging Telescope Array) survey to be achieved by the early 2020s. We bring special attention to modelling the entire chain from photon emission to source detection and cataloguing. Methods. The selection function of galaxy clusters for the upcoming eROSITA mission is investigated by means of extensive and dedicated Monte-Carlo simulations. Employing a combination of accurate instrument characterisation and a state-of-the-art source detection technique, we determine a cluster detection efficiency based on the cluster fluxes and sizes. Results. Using this eROSITA cluster selection function, we find that eROSITA will detect a total of approximately 105 clusters in the extra-galactic sky. This number of clusters will allow eROSITA to put stringent constraints on cosmological models. We show that incomplete assumptions on selection effects, such as neglecting the distribution of cluster sizes, induce a bias in the derived value of cosmological parameters. Conclusions. Synthetic simulations of the eROSITA sky capture the essential characteristics impacting the next-generation galaxy cluster surveys and they highlight parameters requiring tight monitoring in order to avoid biases in cosmological analyses.
- ItemThe AMBRE Project: r-process elements in the Milky Way thin and thick discs(Les Ulis : EDP Sciences, 2018) Guiglion, G.; de Laverny, P.; Recio-Blanco, A.; Prantzos, N.Context. The chemical evolution of neutron capture elements in the Milky Way disc is still a matter of debate. There is a lack of statistically significant catalogues of such element abundances, especially those of the r-process. Aims. We aim to understand the chemical evolution of r-process elements in Milky Way disc. We focus on three pure r-process elements Eu, Gd, and Dy. We also consider a pure s-process element, Ba, in order to disentangle the different nucleosynthesis processes. Methods. We take advantage of high-resolution FEROS, HARPS, and UVES spectra from the ESO archive in order to perform a homogeneous analysis on 6500 FGK Milky Way stars. The chemical analysis is performed thanks to the automatic optimization pipeline GAUGUIN. We present abundances of Ba (5057 stars), Eu (6268 stars), Gd (5431 stars), and Dy (5479 stars). Based on the [α/Fe] ratio determined previously by the AMBRE Project, we chemically characterize the thin and the thick discs, and a metal-rich α-rich population. Results. First, we find that the [Eu/Fe] ratio follows a continuous sequence from the thin disc to the thick disc as a function of the metallicity. Second, in thick disc stars, the [Eu/Ba] ratio is found to be constant, while the [Gd/Ba] and [Dy/Ba] ratios decrease as a function of the metallicity. These observations clearly indicate a different nucleosynthesis history in the thick disc between Eu and Gd-Dy. The [r/Fe] ratio in the thin disc is roughly around +0.1 dex at solar metallicity, which is not the case for Ba. We also find that the α-rich metal-rich stars are also enriched in r-process elements (like thick disc stars), but their [Ba/Fe] is very different from thick disc stars. Finally, we find that the [r/α] ratio tends to decrease with metallicity, indicating that supernovae of different properties probably contribute differently to the synthesis of r-process elements and α-elements. Conclusions. We provide average abundance trends for [Ba/Fe] and [Eu/Fe] with rather small dispersions, and for the first time for [Gd/Fe] and [Dy/Fe]. This data may help to constrain chemical evolution models of Milky Way r- and s-process elements and the yields of massive stars. We emphasize that including yields of neutron-star or black hole mergers is now crucial if we want to quantitatively compare observations to Galactic chemical evolution models.
- ItemPlanets, candidates, and binaries from the CoRoT/Exoplanet programme: The CoRoT transit catalogue(Les Ulis : EDP Sciences, 2018) Deleuil, M.; Aigrain, S.; Moutou, C.; Cabrera, J.; Bouchy, F.; Deeg, H. J.; Almenara, J.-M.; Hébrard, G.; Santerne, A.; Alonso, R.; Bonomo, A.S.; Bordé, P.; Csizmadia, S.; Dìaz, R.F.; Erikson, A.; Fridlund, M.; Gandolfi, D.; Guenther, E.; Guillot, T.; Guterman, P.; Grziwa, S.; Hatzes, A.; Léger, A.; Mazeh, T.; Ofir, A.; Ollivier, M.; Pätzold, M.; Parviainen, H.; Rauer, H.; Rouan, D.; Schneider, J.; Titz-Weider, R.; Tingley, B.; Weingrill, J.The CoRoT space mission observed 163 665 stars over 26 stellar fields in the faint star channel. The exoplanet teams detected a total of 4123 transit-like features in the 177 454 light curves. We present the complete re-analysis of all these detections carried out with the same softwares so that to ensure their homogeneous analysis. Although the vetting process involves some human evaluation, it also involves a simple binary flag system over basic tests: Detection significance, presence of a secondary, difference between odd and even depths, colour dependence, V-shape transit, and duration of the transit. We also gathered the information from the large accompanying ground-based programme carried out on the planet candidates and checked how useful the flag system could have been at the vetting stage of the candidates. From the initial list of transit-like features, we identified and separated 824 false alarms of various kind, 2269 eclipsing binaries among which 616 are contact binaries and 1653 are detached ones, 37 planets and brown dwarfs, and 557 planet candidates. We provide the catalogue of all these transit-like features, including false alarms. For the planet candidates, the catalogue gives not only their transit parameters but also the products of their light curve modelling: Reduced radius, reduced semi-major axis, and impact parameter, together with a summary of the outcome of follow-up observations when carried out and their current status. For the detached eclipsing binaries, the catalogue provides, in addition to their transit parameters, a simple visual classification. Among the planet candidates whose nature remains unresolved, we estimate that eight (within an error of three) planets are still to be identified. After correcting for geometric and sensitivity biases, we derived planet and brown dwarf occurrences and confirm disagreements with Kepler estimates, as previously reported by other authors from the analysis of the first runs: Small-size planets with orbital period less than ten days are underabundant by a factor of three in the CoRoT fields whereas giant planets are overabundant by a factor of two. These preliminary results would however deserve further investigations using the recently released CoRoT light curves that are corrected of the various instrumental effects and a homogeneous analysis of the stellar populations observed by the two missions.
- ItemThe MUSE Hubble Ultra Deep Field Survey : XII. Mg II emission and absorption in star-forming galaxies(Les Ulis : EDP Sciences, 2018) Feltre, Anna; Bacon, Roland; Tresse, Laurence; Finley, Hayley; Carton, David; Blaizot, Jérémy; Bouché, Nicolas; Garel, Thibault; Inami, Hanae; Boogaard, Leindert A.; Brinchmann, Jarle; Charlot, Stéphane; Chevallard, Jacopo; Contini, Thierry; Michel-Dansac, Leo; Mahler, Guillaume; Marino, Raffaella A.; Maseda, Michael V.; Richard, Johan; Schmidt, Kasper B.; Verhamme, AnneThe physical origin of the near-ultraviolet Mg II emission remains an underexplored domain, unlike more typical emission lines that are detected in the spectra of star-forming galaxies. We explore the nebular and physical properties of a sample of 381 galaxies between 0.70 < z < 2.34 drawn from the MUSE Hubble Ultra Deep Survey. The spectra of these galaxies show a wide variety of profiles of the Mg II λλ2796, 2803 resonant doublet, from absorption to emission. We present a study on the main drivers for the detection of Mg II emission in galaxy spectra. By exploiting photoionization models, we verified that the emission-line ratios observed in galaxies with Mg II in emission are consistent with nebular emission from HII regions. From a simultaneous analysis of MUSE spectra and ancillary Hubble Space Telescope information through spectral energy distribution fitting, we find that galaxies with Mg II in emission have lower stellar masses, smaller sizes, bluer spectral slopes, and lower optical depth than those with absorption. This leads us to suggest that Mg II emission is a potential tracer of physical conditions that are not merely related to those of the ionized gas. We show that these differences in Mg II emission and absorption can be explained in terms of a higher dust and neutral gas content in the interstellar medium (ISM) of galaxies showing Mg II in absorption, which confirms the extreme sensitivity of Mg II to the presence of the neutral ISM. We conclude with an analogy between the Mg II doublet and the Ly α line that lies in their resonant nature. Further investigations with current and future facilities, including the James Webb Space Telescope, are promising because the detection of Mg II emission and its potential connection with Lyα could provide new insights into the ISM content in the early Universe.