Recursos de colección

ORBi Open Repository and Bibliography (301.662 recursos)

In may 2007, the ULg's Administrative Board (joined in June 2007 by the FUSAGx) decided to create an institutional repository and defined a strong institutional self-archiving policy to increase the visibility, accessibility and impact of the University's publications (Board's decision). This decision led to the official launch, in November 2008, of the ORBi platform including both the Academic Bibliography and the Institutional Repository of the Wallonia-Europe University Academy.

Physical, chemical, mathematical & earth Sciences => Space science, astronomy & astrophysics

Mostrando recursos 1 - 20 de 109

  1. Strongly interacting dark matter doesn't explain the DAMA signal

    Laletin, Maxim

  2. L'astronomie dans le monde - 09/2016

    Manfroid, Jean
    Vénus - Phobos et Deimos - Une nouvelle planète naine au-delà de Neptune - Ondes gravitationnelles - L’oxygène de la comète 67P - Averse intergalactique - Méthanol protoplanétaire - TRAPPIST-1 - Les jupiters chaudes de M67

  3. First Detection of the Nitric Oxide Dayglow on Mars

    Stevens, Michael H.; Siskind, David E.; Evans, J. Scott; Fox, Jane L.; Jain, Sonal; Deighan, Justin; Schneider, Nicholas M.; Stewart, A. Ian F.; Crismani, Matteo; Stiepen, Arnaud; Chaffin, Michael S.; McClintock, William E.; Holsclaw, Greg; Lefevre, Franck; Lo, Daniel; Clarke, John T.; Montmessin, Franck; Jakosky, Bruce
    Nitric oxide (NO) is a well-known indicator of solar and auroral activity in the terrestrial upper atmosphere. Direct measurements of NO on Mars can therefore constrain studies of energetic processes controlling the composition and structure of its upper atmosphere (80-200 km). Identifying and quantifying these processes is one of the science objectives of NASA’s Mars Atmosphere and Volatile Evolution (MAVEN) mission currently orbiting Mars. NO can be observed directly by solar resonance fluorescence in the mid-ultraviolet (MUV). Indeed, this approach has routinely been used to measure terrestrial NO for 50 years. On Mars, this “dayglow” emission is very weak relative...

  4. Unveiling Mars nightside mesosphere dynamics by IUVS/MAVEN global images of NO nightglow

    Stiepen, Arnaud; Jain, S. K.; Schneider, N. M.; Milby, Z.; Deighan, J. I.; Gonzàlez-Galindo, F.; Gérard, Jean-Claude; Forget, F.; Bougher, S.; Stewart, A. I. F.; Royer, E.; Stevens, M. H.; Evans, J. S.; Chaffin, M. S.; Crismani, M.; McClintock, W. E.; Clarke, J. T.; Holsclaw, G. W.; Montmessin, F.; Lo, D. Y.
    We analyze the morphology of the ultraviolet nightglow in the Martian upper atmosphere through Nitric Oxide (NO) δ and γ bands emissions observed by the Imaging Ultraviolet Spectrograph instrument on the Mars Atmosphere and Volatile EvolutioN spacecraft. The seasonal dynamics of the Martian thermosphere-mesosphere can be constrained based on the distribution of these emissions. We show evidence for local (emission streaks and splotches) and global (longitudinal and seasonal) variability in brightness of the emission and provide quantitative comparisons to GCM simulations.

  5. MAVEN IUVS Observations of the Aftermath of the Comet Siding Spring Meteor Shower on Mars

    Schneider, N. M.; Crismani, M.; Deighan, J. I.; Plane, J. M. C.; Evans, J. S.; Jain, S. K.; Stewart, A. I. F.; Carrillo-Sanchez, J. D.; McClintock, W. E.; Chaffin, M. S.; Stiepen, Arnaud; Stevens, M. H.; Yelle, R. V.; Clarke, J. T.; Holsclaw, G. M.; Montmessin, F.; Jakosky, B. M.
    A comet's close passage by Mars deposited an unprecedented amount of vaporized dust whose elements were detected by the MAVEN spacecraft.

  6. Mars topographic clouds: MAVEN/IUVS observations and LMD MGCM predictions

    Schneider, Nicholas M.; Connour, Kyle; Forget, Francois; Deighan, Justin; Jain, Sonal; Vals, Margaux; Wolff, Michael J.; Chaffin, Michael S.; Crismani, Matteo; Stewart, A. Ian F.; McClintock, William E.; Holsclaw, Greg; Lefevre, Franck; Montmessin, Franck; Stiepen, Arnaud; Stevens, Michael H.; Evans, J. Scott; Yelle, Roger; Lo, Daniel; Clarke, John T.; Jakosky, Bruce
    The Imaging Ultraviolet Spectrograph (IUVS) instrument on the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft takes mid-UV spectral images of the Martian atmosphere. From these apoapse disk images, information about clouds and aerosols can be retrieved and comprise the only MAVEN observations of topographic clouds and cloud morphologies. Measuring local time variability of large-scale recurring cloud features is made possible with MAVEN’s ~4.5-hour elliptical orbit, something not possible with sun-synchronous orbits. We have run the LMD MGCM (Mars global circulation model) at 1° x 1° resolution to simulate water ice cloud formation with inputs consistent with observing parameters and Mars...

  7. First Retrieval of Thermospheric Carbon Monoxide From Mars Dayglow Observations

    Evans, J. Scott; Stevens, Michael H.; Jain, Sonal; Deighan, Justin; Lumpe, Jerry; Schneider, Nicholas M.; Stewart, A. Ian; Crismani, Matteo; Stiepen, Arnaud; Chaffin, Michael S.; Mayyasi-Matta, Majd A.; McClintock, William E.; Holsclaw, Greg; Lefevre, Franck; Lo, Daniel; Clarke, John T.; Montmessin, Franck; Bougher, Stephen W.; Bell, Jared M.; Eparvier, Frank; Thiemann, Ed; Mahaffy, Paul R.; Benna, Mehdi; Elrod, Meredith K.; Jakosky, Bruce
    As a minor species in the Martian thermosphere, Carbon Monoxide (CO) is a tracer that can be used to constrain changing circulation patterns between the lower thermosphere and upper mesosphere of Mars. By linking CO density distributions to dynamical wind patterns, the structure and variability of the atmosphere will be better understood. Direct measurements of CO can therefore provide insight into the magnitude and pattern of winds and provide a metric for studying the response of the atmosphere to solar forcing. In addition, CO measurements can help solve outstanding photochemical modeling problems in explaining the abundance of CO at Mars....

  8. Mars’ seasonal mesospheric transport seen through nitric oxide nightglow

    Milby, Zachariah; Stiepen, Arnaud; Jain, Sonal; Schneider, Nicholas M.; Deighan, Justin; Gonzalez-Galindo, Francisco; Gérard, Jean-Claude; Stevens, Michael H.; Bougher, Stephen W.; Evans, J. Scott; Stewart, A. Ian; Chaffin, Michael; Crismani, Matteo; McClintock, William E.; Clarke, John T.; Holsclaw, Greg; Montmessin, Franck; Lefevre, Franck; Forget, Francois; Lo, Daniel Y.; Hubert, Benoît; Jakosky, Bruce
    We analyze the ultraviolet nightglow in the atmosphere of Mars through nitric oxide (NO) δ and γ band emissions as observed by the Imaging UltraViolet Spectrograph (IUVS) instrument onboard the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft when it is at apoapse and periapse.In the dayside thermosphere of Mars, solar extreme-ultraviolet radiation dissociates CO[SUB]2[/SUB] and N[SUB]2[/SUB] molecules. O([SUP]3[/SUP]P) and N([SUP]4[/SUP]S) atoms are carried from the dayside to the nightside by the day-night hemispheric transport process, where they descend through the nightside mesosphere and can radiatively recombine to form NO(C[SUP]2[/SUP]Π). The excited molecules rapidly relax by emitting photons in the UV...

  9. L'astronomie dans le monde - 06/2016

    Manfroid, Jean
    Chocs d’amas - Amas de galaxies - Halos sur Pluton - Makémaké - Comète sans queue – Titan – Planètes Kepler - Transit de Mercure - Quatre lasers au-dessus de Paranal – NGC 1332 - Eau sur Mars

  10. X-rays from colliding winds in massive binaries

    Nazé, Yaël; Rauw, Grégor
    In a massive binary, the strong shock between the stellar winds may lead to the generation of bright X-ray emission. While this phenomenon was detected decades ago, the detailed study of this emission was only made possible by the current generation of X-ray observatories. Through dedicated monitoring and observations at high resolution, unprecedented information was revealed, putting strong constraints on the amount and structure of stellar mass-loss.

  11. Investigating the Magnetospheres of Rapidly Rotating B-type Stars

    Fletcher, C. L.; Petit, V.; Nazé, Yaël; Wade, G. A.; Townsend, R. H.; Owocki, S. P.; Cohen, D. H.; David-Uraz, A.; Shultz, M.
    Recent spectropolarimetric surveys of bright, hot stars have found that ~10% of OB-type stars contain strong (mostly dipolar) surface magnetic fields (~kG). The prominent paradigm describing the interaction between the stellar winds and the surface magnetic field is the magnetically confined wind shock (MCWS) model. In this model, the stellar wind plasma is forced to move along the closed field loops of the magnetic field, colliding at the magnetic equator, and creating a shock. As the shocked material cools radiatively it will emit X-rays. Therefore, X-ray spectroscopy is a key tool in detecting and characterizing the hot wind material confined...

  12. The supergiant O + O binary system HD 166734: a new study

    Gosset, Eric; Mahy, Laurent; Damerdji, Yassine; Nitschelm, C.; Sana, H.; Eenens, P.; Nazé, Yaël
    We present here a modern study of the radial velocity curve and of the photometric light curve of the very interesting supergiant O7.5If + O9I(f) binary system HD 166734. The physical parameters of the stars and the orbital parameters are carefully determined. We also perform the analysis of the observed X-ray light curve of this colliding-wind binary.

  13. Up and downs of a magnetic oblique rotator viewed at high resolution

    Nazé, Yaël; Zhekov, S. A.; Ud-Doula, A.
    In 2006, the Of?p star HD191612 became the second O-star where a magnetic field was discovered. It provided a benchmark to understand the Of?p phenomenon as a whole. Ten years later, an X-ray monitoring performed at high-resolution reveals the behaviour of the hottest magnetospheric plasma: it is located at ~ 2R [SUB]⊙[/SUB], hot but not extreme (log(T) ~ 7), producing unshifted lines, and displaying a very repetitive variability. A direct comparison with simulations yields an overall good agreement, with only a few further improvements needed.

  14. The quest for magnetic massive stars in the Magellanic Clouds

    Nazé, Yaël; Bagnulo, S.; Walborn, N. R.; Morrell, N.; Wade, G. A.; Szymanski, M. K.; Townsend, R. H. D.
    The Of?p category was introduced more than 40 years ago to gather several Galactic stars with some odd properties. Since 2000, spectropolarimetry, high-resolution spectroscopy, long-term photometry, and X-ray observations have revealed their nature: magnetic oblique rotators - they all have magnetic fields that confine their winds. Several Of?p stars have now been detected in the Magellanic Clouds, likely the prototypes of magnetic massive stars at low metallicity. This contribution will present the most recent photometric, spectroscopic, and spectropolarimetric data, along with the first modeling of these objects.

  15. A legacy survey of early B-stars using the RGS

    Nazé, Yaël; Cazorla, C.; Rauw, Grégor; Morel, Thierry
    Despite their relatively large incidence among early-type stars, only a few B-stars have been observed with X-ray gratings. We therefore undertook a legacy project with XMM to gather high- resolution spectra of a set of early B stars selected on the basis of their high RASS count rate. This poster presents the preliminary results of this project.

  16. The flaring activity of PMS in NGC6530

    Rauw, Grégor; Nelissen, Marie; Nazé, Yaël
    We have obtained XMM-Newton observations of the very young open cluster NGC6530 at four different epochs. The data reveal a wealth of relatively faint X-ray sources that are correlated with PMS members of NGC6530. We have investigated the X-ray properties of these sources with emphasis on their flaring activity. We compare our results with the properties of the sources (stellar masses, rotation rates,...) as inferred from optical studies.

  17. Zeta Pup variability revisited

    Nazé, Yaël; Ramiaramanantsoa; Stevens, I.R.; Howarth, I.D.; Moffat, A.F.J.
    In 2013, we reported on the variability properties of zeta Puppis, one of the hottest and closest massive stars. In particular, while short-term stochastic variability seems absent, ”trends” with a typical timescale longer than the exposure length were detected. Since then, such features were found in other objects as well, and the favored scenario links them to co-rotating wind structures. Using new observations as well as optical photometry, we revisit the variability of zeta Pup with the aim of assessing the CIR scenario.

  18. The LBTI Fizeau imager – II. Sensitivity of the PSF and the MTF to adaptive optics errors and to piston errors

    Patru, F.; Esposito, S.; Puglisi, A.; Riccardi, A.; Pinna, E.; Arcidiacono, C.; Antichi, J.; Mennesson, B.; Defrere, Denis; Hinz, P. M.; Hill, J. M.
    Peer reviewed

  19. VizieR Online Data Catalog: Polarization of quasars (Hutsemekers+, 2017)

    Hutsemekers, Damien; Hall, P.; Sluse, Dominique
    This Table contains optical linear polarization measurements of 192 quasars obtained in April 2003, April 2007, and October 2007 with the ESO Faint Object Spectrograph and Camera (EFOSC2) instrument attached to the 3.6m telescope at the La Silla Observatory. (1 data file).

  20. Discrete and broadband electron acceleration in Jupiter's powerful aurora

    Mauk, B. H.; Haggerty, D. K.; Paranicas, C.; Clark, G.; Kollmann, P.; Rymer, A. M.; Bolton, S. J.; Levin, S. M.; Adriani, A.; Allegrini, F.; Bagenal, F.; Bonfond, Bertrand; Connerney, J. E. P.; Gladstone, G. R.; Kurth, W. S.; McComas, D. J.; Valek, P.
    Peer reviewed

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