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See detailEarly-type stars observed in the ESO UVES Paranal Observatory Project - III. Sub-parsec and au-scale structure in the interstellar medium
Smoker, J. V.; Bagnulo, S.; Cabanac, R. et al

in Monthly Notices of the Royal Astronomical Society (2011), 414

UVES interstellar observations from the Paranal Observatory Project are presented for early-type stars located in the line of sight to the nearby open clusters IC 2391 (Omni Vel) and NGC 6475 (M7), with ... [more ▼]

UVES interstellar observations from the Paranal Observatory Project are presented for early-type stars located in the line of sight to the nearby open clusters IC 2391 (Omni Vel) and NGC 6475 (M7), with spectroscopic resolution R˜ 80 000 and signal-to-noise ratios in the Ti II (3383 Å), Ca II K, CH[SUP]+[/SUP] (4232 Å), Na I D and K I (7698 Å) lines of several hundred. The sightlines are a mixture of cluster and non-cluster objects. A total of 22 early-type stars (A and B type) are present in our sample towards IC 2391, with 21 towards NGC 6475/M7, and enable us to probe for differences in column density on scales from ˜0.07 to 7.3 and ˜0.05 to 4.9 pc in the respective clusters. Additionally, towards Praesepe the Na I D interstellar variation only is probed towards 13 sightlines and transverse scales of ˜0.16-10.7 pc at R= 70 000. Towards IC 2391 variations are found in Ti II, Ca II K and Na I D column density in different sightlines of up to 0.7, 1.0 and 1.8 dex (excluding one star), respectively. This kind of variability correlates well with the Hipparcos parallax of the objects, and probes structure within the Local Bubble. For cluster-only objects the variations are 0.3, 0.3 and 0.5 dex, respectively. For the field of view towards NGC 6475 the corresponding maximum variations are somewhat smaller, being 0.5, 0.3, 0.8 and 1.0 dex for Ti II, Ca II K, Na I and K I, respectively, for all objects and 0.4, 0.2, 0.6 and 0.7 dex for the cluster-only objects. These are uncorrelated with parallax, and again demonstrate that Ca II K tends to be more smoothly distributed than Na I D. A few likely cluster sightlines show evidence for CH[SUP]+[/SUP] and variations in this molecular species of a factor of 10 in equivalent width over sub-pc scales. Towards Praesepe variation in interstellar Na I D is small, being a maximum of only ˜0.4 dex (including measurement errors), but with fewer sightlines studied. Overall, the scatter in the data is similar for the singly ionized species Ti II and Ca II, lending more support to the hypothesis that these two species sample similar parts of the interstellar medium (ISM). This also appears to be the case for the neutral species Na I D and K I in the one cluster studied. Finally, multiple-epoch observations from a variety of archive sources are used to search for astronomical unit (au) scale structure in the ISM towards 46 sightlines. There are tentative indications of structure on scales of tens to thousands of au for three sightlines. Future observations will confirm the veracity or otherwise of the time-variable components and others presented. Based on observations taken at UT2, Kueyen, Cerro Paranal, Chile, ESO DDT programme 265.D-5655(A), UVES Paranal Observatory Project and using FEROS on the ESO 2.2-m telescope, La Silla, Chile, programme ID 078.C-0493(A), the Observatoire de Haute Provence, France, the Pic du Midi telescope, France and the AAO archive. [less ▲]

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See detailEarly-type stars observed in the ESO UVES Paranal Observatory Project - IV. Studies of CN, CH+ and CH in the interstellar medium
Smoker, J.; Ledoux, C.; Jehin, Emmanuel ULg et al

in Monthly Notices of the Royal Astronomical Society (2013)

High spectral resolution (˜80 000) and signal-to-noise observations from the Ultraviolet and Visual Echelle Spectrograph Paranal Observatory Project (UVES-POP) are used to study the interstellar molecular ... [more ▼]

High spectral resolution (˜80 000) and signal-to-noise observations from the Ultraviolet and Visual Echelle Spectrograph Paranal Observatory Project (UVES-POP) are used to study the interstellar molecular lines CN (3874 Å), CH[SUP]+[/SUP] (3957, 4232 Å) and CH (3886, 4300 Å) towards 74 O- and B-type stellar sightlines. Additionally, archive data are presented for 140 ELODIE early-type stellar sightlines at R = 42 000, plus 25 FEROS at R = 48 000 and 3 UVES at R > 50 000, mainly in the CH[SUP]+[/SUP] (4232 Å) and CH (3886, 4300 Å) transitions. Detection rates are ˜45 per cent for CN and ˜67 per cent for the other lines in the POP sample, and ˜10-15 per cent for CH[SUP]+[/SUP] and CH lines in the additional sample. CH and CH[SUP]+[/SUP] are well correlated between log[N(CH) cm[SUP]-2[/SUP]]˜12-14, implying that these clouds are CH[SUP]+[/SUP]-like CH and not CN-like CH. CH is also very well correlated with Na I D in the range log[N(Na I cm[SUP]-2[/SUP]]) ˜12.2-14.2. A few sightlines show tentative velocity shifts of ˜2 km s[SUP]-1[/SUP] between CH and CH[SUP]+[/SUP], which appear to be caused by differences in component strength in blends, and hence do not provide firm evidence for shocks. Finally, we describe a search for [SUP]13[/SUP]CH[SUP]+[/SUP] in a sightline towards HD 76341. No [SUP]13[/SUP]CH[SUP]+[/SUP] is detected, placing a limit on the [SUP]13[/SUP]CH[SUP]+[/SUP] to [SUP]12[/SUP]CH[SUP]+[/SUP] ratio of ˜0.01. If a formal fit is attempted, the equivalent width ratio in the two isotopes is a factor ˜90 but with large errors. [less ▲]

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See detailEarth and sea-level change projections with the Earth system model of intermediate complexity LOVECLIM
Goelzer, H.; Huybrechts, P.; Loutre, M. F. et al

Conference (2010, May)

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See detailAn Earth-like correspondence between Saturn's auroral features and radio emission
Kurth, William S.; Gurnett, Donald A.; Clarke, John T. et al

in Nature (2005), 433(7027), 722-725

Saturn is a source of intense kilometre-wavelength radio emissions that are believed to be associated with its polar aurorae(1,2), and which provide an important remote diagnostic of its magnetospheric ... [more ▼]

Saturn is a source of intense kilometre-wavelength radio emissions that are believed to be associated with its polar aurorae(1,2), and which provide an important remote diagnostic of its magnetospheric activity. Previous observations implied that the radio emission originated in the polar regions, and indicated a strong correlation with solar wind dynamic pressure(1,3-7). The radio source also appeared to be fixed near local noon and at the latitude of the ultraviolet aurora(1,2). There have, however, been no observations relating the radio emissions to detailed auroral structures. Here we report measurements of the radio emissions, which, along with high-resolution images of Saturn's ultraviolet auroral emissions(8), suggest that although there are differences in the global morphology of the aurorae, Saturn's radio emissions exhibit an Earth-like correspondence between bright auroral features and the radio emissions. This demonstrates the universality of the mechanism that results in emissions near the electron cyclotron frequency narrowly beamed at large angles to the magnetic field(9,10). [less ▲]

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See detailEarth-like planet imaging: why we care about exozodis (invited)
Absil, Olivier ULg

Scientific conference (2010, June 28)

We estimate the amount of exozodiacal light that can be tolerated around nearby main sequence stars without jeopardizing the detection of Earth-like exoplanets (exoEarths) with a space-based visible ... [more ▼]

We estimate the amount of exozodiacal light that can be tolerated around nearby main sequence stars without jeopardizing the detection of Earth-like exoplanets (exoEarths) with a space-based visible coronagraph or mid-infrared interferometer. We also address the possible effects of resonant structures in exozodis. We then review the sensitivity of ground-based interferometric instruments to exozodiacal disks. We show that the current performances are not sufficient to help prepare future exoEarth imaging missions, and discuss how new ground- or space-based instruments could improve the current sensitivity to exozodiacal disks down to a suitable level. [less ▲]

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See detailEarth-like planets: science performance predictions for future nulling interferometry missions
Defrere, Denis ULg; Lay, O.; den Hartog, R. et al

in Schöller, Markus; Danchi, William; Delplancke, Françoise (Eds.) Optical and Infrared Interferometry (2008, July 01)

With the launch of planet-transit missions such as CoRoT and Kepler, it is expected that Earth-sized planets orbiting distant stars will be detected soon. This milestone will open the path towards the ... [more ▼]

With the launch of planet-transit missions such as CoRoT and Kepler, it is expected that Earth-sized planets orbiting distant stars will be detected soon. This milestone will open the path towards the definition of missions able to study the atmosphere of Earth-sized extrasolar planets, with the identification of bio-signatures as one of the main objectives. In that respect, both the European Space Agency (ESA) and the National Aeronautics and Space Administration (NASA) have identified nulling interferometry as one of the most promising techniques. Trying to minimize the cost and the technological risks while maximizing the scientific return, ESA and NASA recently converged towards a single mission architecture, the Emma X-array. In this paper, we present the expected science performance of this concept computed with two independent mission simulators. The impact of different observational parameters such as planet radius and exozodiacal cloud density is specifically addressed. [less ▲]

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See detailEarthquake imprints on 400 years of marine sedimentation in the western Gulf of Corinth, Greece
Beckers, Arnaud ULg; Hubert, Aurelia ULg; Beck, Christian et al

Poster (2014, August 18)

The Corinth rift is one of the fastest spreading rifts on Earth. In the western tip of the Rift, no major historical earthquake (Mw≥6) is known for the last 300 yrs, while the geodetic extension rate is ... [more ▼]

The Corinth rift is one of the fastest spreading rifts on Earth. In the western tip of the Rift, no major historical earthquake (Mw≥6) is known for the last 300 yrs, while the geodetic extension rate is the highest of the whole Corinth Rift. The question of seismic hazard is consequently particularly relevant. In this framework, we investigated the offshore sediments in order to look for sedimentary signature of past earthquakes. 12 short gravity cores have been retrieved in different environments: two shelves (40 and 100 m deep), one sub-basin (180 m deep) and the deep Gulf axis (330 m deep). The cores are 0.5 to 0.85 m long, permitting to analyze up to 400 yrs of sedimentation. Several sedimentological analyses have been performed: magnetic susceptibility, grain-size, XRF, ASM. Chronology is based on 137Cs and 210Pb decay. In parallel, an in-depth analysis of existing and newly found documents has been done to re-interpret macroseismic intensity fields of historical earthquakes and to build an updated earthquake catalogue for the area. These new data allowed us to estimate a macroseismic intensity threshold for submarine slope failures in the area, based on 16 reported events. Sedimentary events have been identified in all cores. On the first shelf, despite a visually homogenous, silty, sedimentation, 3 events have been highlighted by high resolution grain-size analysis and 210Pb decay profile’s disturbances. The upper one could be a back-wash flow tsunami deposit. On the second shelf, 4 high-concentration density flow deposits occurred with a recurrence time of ~58 yrs. In the canyon and in the sub-basin, sandy turbidites occurred with recurrence times of ~26 and ~56 years respectively. The possible seismic origin of these deposits is discussed based on their sedimentary characteristics and the macroseismic intensities assessed for the sediments source areas for each core location. [less ▲]

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See detailThe earthquake sedimentary record in marine sediment from cores in the western part of the Marmara Sea, Turkey
Drab, Laureen; Hubert, Aurelia ULg; Schmidt, Sabine et al

Conference (2012, April)

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See detailThe earthquake sedimentary record in the the Sea of Marmara, Turkey
Hubert, Aurelia ULg; Drab, Loreen; Schmidt, Sabine et al

Conference (2012, October)

The submarine part of the North Anatolian Fault (NAF) is a very significant hazard for the 12 million people living in Istanbul (Turkey). An accurate seismic risk assessment necessitates ... [more ▼]

The submarine part of the North Anatolian Fault (NAF) is a very significant hazard for the 12 million people living in Istanbul (Turkey). An accurate seismic risk assessment necessitates paleoseismological data, which can be retrieved in the Marmara Sea by using sedimentary cores. We present here a record of turbidites obtained in cores spanning the Tekirdag ̆ Basin, the Western High, the Central Basin, and the Cinarcik Basin. In the Tekirdag and Western High the turbidites are synchronous pointing to shaking by earthquakes as a triggering mechanism. Generally seismoturbidites in the Marmara Sea are distinguished from other turbidites based in their large extension, their particular granulometric and their particular geochemical characteristics. The 210Pb and 137Cs radionucleides measurements have also shown that the M=7.4 1912 Mürefte earthquake and the M=7.3 1894 Prince's Island earthquake have left a distinctive sedimentary imprint at the top of the studied cores. The chronology of other seismoturbidites is built combining radiocarbon dating and secular variation patterns of paleo-declination and paleo-inclination. Finally the obtained record is compared to the historical seismicity record. [less ▲]

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See detailThe earthquake sedimentary record in the Western part of the Sea of Marmara, Turkey
Drab, Laureen; Hubert, Aurelia ULg; Schmidt, Sabine et al

in Natural Hazards & Earth System Sciences (2012)

The submarine part of the North Anatolian Fault (NAF) is a very significant hazard for the 12 million people living in Istanbul (Turkey). An accurate seismic risk assess- ment necessitates ... [more ▼]

The submarine part of the North Anatolian Fault (NAF) is a very significant hazard for the 12 million people living in Istanbul (Turkey). An accurate seismic risk assess- ment necessitates paleoseismological data, which can be re- trieved in the Sea of Marmara only using sedimentary cores. Here a record of turbidites was obtained in five cores span- ning the Tekirdag ̆ Basin, the Western High and the Central Basin linked by the Tekirdag ̆ Fault Segment. The turbidites are synchronous at different sites across basins and structural highs. The only possible triggering mechanism is thus shak- ing related to major earthquakes. In particular the M=7.4 1912 Mu ̈refte earthquake has let a distinctive sedimentary imprint in all the studied cores. Radiocarbon dating implies a turbidite recurrence interval of about 300 years. In addi- tion the low number of turbidites documented in the Central Basinsuggestsquasi-synchronousrupturesoftheTekirdag ̆ Segment and the adjacent Central Segment of the NAF or a partial seismic slip on the Central Segment. Both scenarii have implications regarding seismic hazard. Finally through we obtained a reliable paleoseismological record of the rup- tures along the Tekirdag ̆ Segment, further chronological con- straints are needed to accurately date the events and correlate them with known historical earthquakes. [less ▲]

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See detailThe Earthquake Sedimentary record of The Lake Hazar along the East Anatolian Fault in Turkey
Boes, Xavier; Hubert, Aurelia ULg; Garcia, David et al

in Geophysical Research Abstracts (2009, April), 11

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See detailThe earthquake sedimentary record of the Marmara Sea, Turkey
Drab, Laureen; Hubert, Aurelia ULg; Schmidt, Sabine et al

in Geophysical Research Abstracts (2010, May)

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See detailEarthquake-induced hazards in mountain regions: a review of case histories from Central Asia – an inaugural lecture to the society.
Havenith, Hans-Balder ULg; Bourdeau, Céline

in Geologica Belgica (2010), 13/3

This paper presents a summary of the main trigger factors of earthquake-induced landslides as well as a review of case histories of major landslide-triggering earthquake events in Central Asia. The goal ... [more ▼]

This paper presents a summary of the main trigger factors of earthquake-induced landslides as well as a review of case histories of major landslide-triggering earthquake events in Central Asia. The goal is to analyse the relationship between geological, tectonic and morphological conditions and the susceptibility to seismic slope failure and to show the potential long-term contribution of seismic ground motion dynamics, such as site effects and liquefaction, to slope failure. Case histories related to five M>7 earthquake events in the Tien Shan and Pamir Mountains are outlined: the earthquakes of Kemin in 1911, Sarez in 1911, Khait in 1949, Gissar in 1989 and Suusamyr in 1992. The Kainama earth-flow case history of 2005 is added to document possible mid-term effects of smaller earthquakes. These events show that in the Central Asian Mountains, two types of seismically triggered mass movements may have particularly disastrous effects: massive long rockslides and medium-sized earth flows made of loess – or a mixture of both. Actually, the most catastrophic mass movement of the last century in Central Asia triggered by the 1949 Khait earthquake was a massive long runout rock avalanche, which had gained a very high velocity due to the entrainment of loess sediments and related lubrification. [less ▲]

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See detailEarthquake-induced landslide hazards in Tajikistan
Havenith, Hans-Balder ULg; Schlögel, Romy

in Mountain risks : bringing science to society - proceedings of the Mountain Risks (2010)

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See detailEarthquakes, Landslides, Dams and Reservoirs in the Tien Shan, Central Asia
Havenith, Hans-Balder ULg; Abdrakhmatov, Kanatbek; Torgoev, Isakbek et al

in Margottini, Claudio; Sassa, Kyoji (Eds.) Landslide Science and Practice (2013)

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See detailEarthworms smell microorganisms in soil
Zirbes, Lara ULg; Verheggen, François ULg; Mescher, Mark et al

Poster (2011)

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See detailEarthworms use odor cues to locate and feed on microorganisms in soil
Zirbes, Lara ULg; Mark, Mescher; Vrancken, Véronique ULg et al

in PLoS ONE (2011), 6(7), 21927

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See detailThe EASE Scenario: A New Origin for Metal-Poor Stars?
Jehin, Emmanuel ULg; Magain, Pierre ULg; Noels-Grötsch, Arlette ULg et al

in Weiss, A.; Abell, T.; Hill, V. (Eds.) The First Stars (2000)

We have analysed high resolution and high signal-to-noise spectra of 21 mildly metal-poor stars. The correlations between the relative abundances of 16 elements have been studied, with a special emphasis ... [more ▼]

We have analysed high resolution and high signal-to-noise spectra of 21 mildly metal-poor stars. The correlations between the relative abundances of 16 elements have been studied, with a special emphasis on the neutron-capture ones. This analysis reveals the existence of two sub-populations of field metal-poor stars which differ by the behaviour of the s-process elements versus the alpha and r-process elements. We suggest a scenario for the formation of metal-poor stars, which closely relates the origin of these stars to the evolution of globular clusters. [less ▲]

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See detailThe EASE Scenario: Dynamical Study of the Supernova Phase
Parmentier, Geneviève ULg; Jehin, Emannuel; Magain, Pierre ULg et al

in Weiss, A.; Abell, T.; Hill, V. (Eds.) The First Stars (2000)

We revisit the most often encountered argument against self-enrichment in globular clusters, namely the ability of a few number of supernovae to disrupt the proto-globular cloud. We show that, within the ... [more ▼]

We revisit the most often encountered argument against self-enrichment in globular clusters, namely the ability of a few number of supernovae to disrupt the proto-globular cloud. We show that, within the context of the Fall and Rees theory, primordial proto-globular cluster clouds may sustain several hundreds of Type II supernovae. Furthermore, the corresponding self-enrichment level is in agreement with galactic halo globular cluster metallicities. [less ▲]

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