C. Gry

Aix-Marseille Université, Marsiglia, Provence-Alpes-Côte d'Azur, France

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Publications (207)488.07 Total impact

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    ABSTRACT: We report additional detections of the chloronium molecular ion, H$_2$Cl$^+$, toward four bright submillimeter continuum sources: G29.96, W49N, W51, and W3(OH). With the use of the HIFI instrument on the Herschel Space Observatory, we observed the $2_{12}-1_{01}$ transition of ortho-H$_2^{35}$Cl$^+$ at 781.627 GHz in absorption toward all four sources. Much of the detected absorption arises in diffuse foreground clouds that are unassociated with the background continuum sources and in which our best estimates of the $N({\rm H_2Cl^+})/N({\rm H})$ ratio lie in the range $(0.9 - 4.8) \times 10^{-9}$. These chloronium abundances relative to atomic hydrogen can exceed the predictions of current astrochemical models by up to a factor of 5. Toward W49N, we have also detected the $2_{12}-1_{01}$ transition of ortho-H$_2^{37}$Cl$^+$ at 780.053 GHz and the $1_{11}-0_{00}$ transition of para-H$_2^{35}$Cl$^+$ at 485.418 GHz. These observations imply $\rm H_2^{35}Cl^+/H_2^{37}Cl^+$ column density ratios that are consistent with the solar system $^{35}$Cl/$^{37}$Cl isotopic ratio of 3.1, and chloronium ortho-to-para ratios consistent with 3, the ratio of spin statistical weights.
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    Cecile Gry, Edward B. Jenkins
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    ABSTRACT: We offer a new, more inclusive, picture of the local interstellar medium, where it is composed of a single, monolithic cloud that surrounds the Sun in all directions. Our study of velocities based on Mg II and Fe II ultraviolet absorption lines indicates that the cloud has an average motion consistent with the velocity vector of gas impacting the heliosphere and does not behave like a rigid body: gas within the cloud is being differentially decelerated in the direction of motion, and the cloud is expanding in directions perpendicular to this flow, much like the squashing of a balloon. The outer boundary of the cloud is in average 10 pc away from us but is highly irregular, being only a few parsecs away in some directions, with possibly a few extensions up to 20 pc. Average H I volume densities vary between 0.03 and 0.1 cm-3 over different sight lines. Metals appear to be significantly depleted onto grains, and there is a steady increase in this effect from the rear of the cloud to the apex of motion. There is no evidence that changes in the ionizing radiation influence the apparent abundances. Additional, secondary velocity components are detected in 60 % of the sight lines. Almost all of them appear to be interior to the volume holding the gas that we identify with the main cloud. Half of the sight lines exhibit a secondary component moving at about - 7.2 km/s with respect to the main component, which may be the signature of an implosive shock propagating toward the cloud's interior.
    Journal of Physics Conference Series 10/2014; 577. DOI:10.1088/1742-6596/577/1/012012
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    ABSTRACT: SPHERE (Spectro-Polarimetric High-contrast Exoplanet Research) is a second-generation instrument for the VLT, optimized for very high-contrast imaging around bright stars. Its primary goal is the detection and characterization of new giant planets around nearby stars, together with the observation of early planetary systems and disks. The Infrared Dual Imager and Spectrograph (IRDIS), one of the three SPHERE subsystems, will provide dual-band imaging in the near-infrared, among with other observing modes such as long slit spectroscopy, classical imaging and infrared polarimetry. IRDIS is able to achieve very high contrast with the help of extreme-AO turbulence compensation, coronography, exceptional image quality, very accurate calibration strategies and advanced data processing. IRDIS underwent extensively laboratory testing during the integration and optimization of SPHERE at IPAG and it is now integrated to the VLT/ESO. We will present the results of performances and operations validations performed with SPHERE. In particular we present the achievable level of contrast and compare it with on-sky results obtained at the VLT/ESO.
    SPIE Astronomical Telescopes + Instrumentation; 07/2014
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    ABSTRACT: The near-infrared imager and spectrograph IRDIS is one of the three science sub-systems of VLT/SPHERE dedicated to the detection and characterization of giant exoplanets at large orbital radii. It offers a wide range of observational modes including dual-band imaging (DBI) with very low differential aberrations, and long slit spectroscopy (LSS) coupled with a classical Lyot coronagraph at low (R = ~50) and medium (R = ~330) resolution. Over the course of 2012 and 2013, IRDIS has been extensively tested in laboratory during the integration and optimization of the SPHERE system. At the beginning of 2014, the instrument has been shipped to Chile and has been reintegrated at the Paranal observatory. We present here a detailed summary of the performance of the DBI and LSS modes obtained in laboratory. We provide a wide range of results covering different observing conditions and setups for the DBI mode, and we show that the instrument reaches the technical specifications in terms of contrast. We also identify some of the limitations that prevent going down much further in contrast while testing in the laboratory. For the LSS mode, we present results obtained both at low and medium resolution in the main setups that will be offered to future users. We demonstrate that the LSS mode will provide a useful characterization tool for the planets detected in DBI mode. Finally, we present the first results obtained on-sky during the first commissioning run of SPHERE at the VLT.
    SPIE Astronomical Telescopes + Instrumentation; 07/2014
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    Cecile Gry, Edward B. Jenkins
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    ABSTRACT: Aims: We offer a new, simpler picture of the local interstellar medium around the Sun (LISM) made of a single continuous cloud enveloping the Sun. This new outlook enables the description of a diffuse cloud from within and brings to light some unexpected properties. Methods: We re-examine the kinematics and abundances of the local interstellar medium, as revealed by the published results for the ultraviolet absorption lines of MgII, FeII and HI. Results: In contrast to previous representations, our new picture of the LISM consists of a single, monolithic cloud that surrounds the Sun in all directions and accounts for most of the matter present in the first 50 parsecs around the Sun. The cloud fills the space around us out to about 9 pc in most directions, although its boundary is very irregular with possibly a few extensions up to 20 pc. The cloud does not behave like a rigid body: gas within the cloud is being differentially decelerated in the direction of motion, and the cloud is expanding in directions perpendicular to this flow, much like a squashed balloon. Average HI volume densities inside the cloud vary between 0.03 and 0.1 cm-3 over different directions. Metals appear to be significantly depleted onto grains, and there is a steady increase in depletion from the rear of the cloud to the apex of motion. There is no evidence that changes in the ionizing radiation influence the apparent abundances. Secondary absorption components are detected in 60% of the sight lines. Almost all of them appear to be interior to the volume occupied by the main cloud. Half of the sight lines exhibit a secondary component moving at about -7.2 km/s with respect to the main component, which may be the signature of a shock propagating toward the cloud's interior.
    Astronomy and Astrophysics 04/2014; 567. DOI:10.1051/0004-6361/201323342 · 4.48 Impact Factor
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    ABSTRACT: Next year the second generation instrument SPHERE will begin science operations at the Very Large Telecope (ESO). This instrument will be dedicated to the search for exoplanets through the direct imaging techniques, with the new generation extreme adaptive optics. In this poster, we present the performances of one of the focal instruments, the Infra-Red Dual-beam Imaging and Spectroscopy (IRDIS). All the results have been obtained with tests in laboratory, simulating the observing conditions in Paranal. We tested several configurations using the sub-system Integral Field Spectrograph (IFS) in parallel and simulating long coronographic exposures on a star, calibrating instrumental ghosts, checking the performance of the adaptive optics system and reducing data with the consortium pipeline. The contrast one can reach with IRDIS is of the order of 2\times 10^{-6}$ at 0.5 arcsec separation from the central star.
    Proceedings of the International Astronomical Union 07/2013; DOI:10.1017/S1743921313007965
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    ABSTRACT: IRDIS filters were designed, manufactured with DIBS technology and tested after integration in the instrument. Spectral and WFE measurements indicated that filters are well within specifications, allowing differential aberrations below 10nm rms.
    Optical Interference Coatings; 06/2013
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    ABSTRACT: IRDIS is one of the science sub-systems of VLT/SPHERE dedicated to the detection and characterization of giant exoplanets at large orbital radii with high-contrast direct imaging. It offers a unique set of observational modes including dual-band imaging (DBI) with very low differential aberrations, and long slit spectroscopy (LSS) coupled with a classical Lyot coronograph that will be used to obtain spectra at low (R = ~50) and medium (R = ~500) resolution. During the past year, IRDIS has been integrated and tested in laboratory in a standalone configuration, and it has recently been integrated on the full SPHERE bench including the calibration unit, the common path optics and the extreme AO system. We present the first analysis of data obtained during laboratory tests of IRDIS in the DBI mode, both in standalone and with the full SPHERE bench, but without simulated seeing and AO correction. We show the first performance estimates of spectral differential imaging with IRDIS in H-band, which is used to attenuate the speckle noise induced by the instrumental aberrations. Similarly, for the LSS mode we present the first application of the spectral deconvolution data analysis method to attenuate the speckle noise on IRDIS data. Finally we compare these results to simulations that were performed during the development phase of the instrument.
    Proceedings of SPIE - The International Society for Optical Engineering 09/2012; DOI:10.1117/12.926970 · 0.20 Impact Factor
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    ABSTRACT: SPHERE (Spectro-Polarimetric High-contrast Exoplanet Research) is a second generation instrument for the VLT optimized for very high-contrast imaging around bright stars. Its primary science goal is the detection and characterization of giant planets, together with observation of circumstellar environment. The infrared differential imager and spectrograph (IRDIS), one of the three science instruments for SPHERE, provides simultaneous differential imaging in the near infrared, among with long slit spectroscopy, classical imaging and infrared polarimetry. IRDIS is designed to achieve very high contrast with the help of extreme-AO (Strehl < 90%), coronography, exceptional image quality (including non-common-path aberrations compensation), very accurate calibration strategies and very advanced data processing for speckle suppression. In this paper, we report on the latest experimental characterizations of IRDIS performed with SPHERE/SAXO before the preliminary acceptance in Europe.
    Proceedings of SPIE - The International Society for Optical Engineering 07/2012; DOI:10.1117/12.927099 · 0.20 Impact Factor
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    ABSTRACT: SPHERE, a second-generation instrument for the VLT, is currently under performance validation before shipping to Chile. The IRDIS sub-system, an Infra-Red Dual-Imager and Spectrograph, was integrated on the SPHERE bench last December, and this paper tells the story of the 12 months preceding this milestone: the Assembly, integration and Tests (AIT) performed at Laboratoire d'Astrophysique de Marseille (LAM). Key points of the AIT strategy are then presented, and the successes and failures-human, technical, and managerial-of this adventure are discussed. We also report on the excellent optical quality achieved, paramount to guarantee ultimate performance of the SPHERE instrument, thanks to high-quality optical manufacture and a successfully applied alignment strategy.
    Conference on Ground-Based and Airborne Telescopes IV; 01/2012
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    ABSTRACT: We report the strategy and results of our radial velocity follow-up campaign with the SOPHIE spectrograph (1.93-m OHP) of four transiting planetary candidates discovered by the Kepler space mission. We discuss the selection of the candidates KOI-428, KOI-410, KOI-552, and KOI-423. KOI-428 was established as a hot Jupiter transiting the largest and the most evolved star discovered so far and is described by Santerne et al. (2011a). KOI-410 does not present radial velocity change greater than 120 m/s, which allows us to exclude at 3 sigma a transiting companion heavier than 3.4 Mjup. KOI-552b appears to be a transiting low-mass star with a mass ratio of 0.15. KOI-423b is a new transiting companion in the overlapping region between massive planets and brown dwarfs. With a radius of 1.22 +- 0.11 Rjup and a mass of 18.0 +- 0.92 Mjup, KOI-423b is orbiting an F7IV star with a period of 21.0874 +- 0.0002 days and an eccentricity of 0.12 +- 0.02. From the four selected Kepler candidates, at least three of them have a Jupiter-size transiting companion, but two of them are not in the mass domain of Jupiter-like planets. KOI-423b and KOI-522b are members of a growing population of known massive companions orbiting close to an F-type star. This population currently appears to be absent around G-type stars, possibly due to their rapid braking and the engulfment of their companions by tidal decay.
    Astronomy and Astrophysics 06/2011; 533(0004-6361). DOI:10.1051/0004-6361/201117095 · 4.48 Impact Factor
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    ABSTRACT: We report the discovery of a hot Jupiter transiting a subgiant star with an orbital period of 6.87 days thanks to public photometric data from the Kepler space mission and new radial velocity observations obtained by the SOPHIE spectrograph. The planet KOI-428b with a radius of 1.17 +/- 0.04 RJup and a mass of 2.2 +/- 0.4MJup, orbits around a F5IV star with R* = 2.13 +/- 0.06Rsun, M* = 1.48 +/- 0.06 Msun and Teff = 6510 +/- 100 K. The star KOI-428 is the largest and the most evolved star discovered so far with a transiting planet.
    Astronomy and Astrophysics 12/2010; 528. DOI:10.1051/0004-6361/201015764 · 4.48 Impact Factor
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    ABSTRACT: We report the detection of the ground-state rotational transition of the methylidyne cation CH + and its isotopologue 13 CH + toward the remote massive star-forming regions W33A, W49N, and W51 with the HIFI instrument onboard the Herschel satellite. Both lines are seen only in absorption against the dust continuum emission of the star-forming regions. The CH + absorption is saturated over almost the entire velocity ranges sampled by the lines-of-sight that include gas associated with the star-forming regions (SFR) and Galactic foreground material. The CH + column densities are inferred from the optically thin components. A lower limit of the isotopic ratio [ 12 CH + ]/[ 13 CH + ] > 35.5 is derived from the absorptions of foreground material toward W49N. The column density ratio, N(CH +)/N(HCO +), is found to vary by at least a factor 10, between 4 and >40, in the Galactic foreground material. Line-of-sight 12 CH + average abundances relative to total hydrogen are estimated. Their average value, N(CH +)/N H > 2.6 × 10 −8 , is higher than that observed in the solar neighborhood and confirms the high abundances of CH + in the Galactic interstellar medium. We compare this result to the predictions of turbulent dissipation regions (TDR) models and find that these high abundances can be reproduced for the inner Galaxy conditions. It is remarkable that the range of predicted N(CH +)/N(HCO +) ratios, from 1 to ∼50, is comparable to that observed.
    Astronomy and Astrophysics 10/2010; 9131311313(28). DOI:10.1051/0004-6361/201015109 · 4.48 Impact Factor
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    ABSTRACT: We report the detection of the ground state N, J = 1, 3/2 -> 1, 1/2 doublet of the methylidyne radical CH at similar to 532 GHz and similar to 536 GHz with the Herschel/ HIFI instrument along the sight-line to the massive star-forming regions G10.6-0.4 (W31C), W49N, and W51. While the molecular cores associated with these massive star-forming regions show emission lines, clouds in the diffuse interstellar medium are detected in absorption against the strong submillimeter background. The combination of hyperfine structure with emission and absorption results in complex profiles, with overlap of the different hyperfine components. The opacities of most of the CH absorption features are linearly correlated with those of CCH, CN, and HCO+ in the same velocity intervals. In specific narrow velocity intervals, the opacities of CN and HCO+ deviate from the mean trends, giving rise to more opaque absorption features. We propose that CCH can be used as another tracer of the molecular gas in the absence of better tracers, with [CCH]/[H-2] similar to 3.2 +/- 1.1 x 10(-8). The observed [CN]/[CH], [CCH]/[CH] abundance ratios suggest that the bulk of the diffuse matter along the lines of sight has gas densities nH = n(H) + 2n(H-2) ranging between 100 and 1000 cm(-3).
    Astronomy and Astrophysics 10/2010; 521:L16. DOI:10.1051/0004-6361/201015115 · 4.48 Impact Factor
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    ABSTRACT: The HIFI instrument on board the Herschel Space Observatory has been used to observe interstellar nitrogen hydrides along the sight-line towards G10.6-0.4 in order to improve our understanding of the interstellar chemistry of nitrogen. We report observations of absorption in NH N=1-0, J=2-1 and ortho-NH2 1_1,1-0_0,0. We also observed ortho-NH3 1_0-0_0, and 2_0-1_0, para-NH3 2_1-1_1, and searched unsuccessfully for NH+. All detections show emission and absorption associated directly with the hot-core source itself as well as absorption by foreground material over a wide range of velocities. All spectra show similar, non-saturated, absorption features, which we attribute to diffuse molecular gas. Total column densities over the velocity range 11-54 km/s are estimated. The similar profiles suggest fairly uniform abundances relative to hydrogen, approximately 6*10^-9, 3*10^-9, and 3*10^-9 for NH, NH2, and NH3, respectively. These abundances are discussed with reference to models of gas-phase and surface chemistry. Comment: 5 pages, 3 figures, 2 online pages with 2 figures. Accepted for publication in A&A July 6 (Herschel/HIFI special issue)
    Astronomy and Astrophysics 07/2010; 521. DOI:10.1051/0004-6361/201015105 · 4.48 Impact Factor
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    ABSTRACT: We discuss the detection of absorption by interstellar hydrogen fluoride (HF) along the sight line to the submillimeter continuum sources W49N and W51. We have used Herschel's HIFI instrument in dual beam switch mode to observe the 1232.4762 GHz J = 1 - 0 HF transition in the upper sideband of the band 5a receiver. We detected foreground absorption by HF toward both sources over a wide range of velocities. Optically thin absorption components were detected on both sight lines, allowing us to measure - as opposed to obtain a lower limit on - the column density of HF for the first time. As in previous observations of HF toward the source G10.6-0.4, the derived HF column density is typically comparable to that of water vapor, even though the elemental abundance of oxygen is greater than that of fluorine by four orders of magnitude. We used the rather uncertain N(CH)-N(H2) relationship derived previously toward diffuse molecular clouds to infer the molecular hydrogen column density in the clouds exhibiting HF absorption. Within the uncertainties, we find that the abundance of HF with respect to H2 is consistent with the theoretical prediction that HF is the main reservoir of gas-phase fluorine for these clouds. Thus, hydrogen fluoride has the potential to become an excellent tracer of molecular hydrogen, and provides a sensitive probe of clouds of small H2 column density. Indeed, the observations of hydrogen fluoride reported here reveal the presence of a low column density diffuse molecular cloud along the W51 sight line, at an LSR velocity of ~ 24kms-1, that had not been identified in molecular absorption line studies prior to the launch of Herschel. Comment: 4 pages, 3 figures, A&A Letter special issue, accepted on 07/13/2010
    Astronomy and Astrophysics 07/2010; 521. DOI:10.1051/0004-6361/201015082 · 4.48 Impact Factor
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    ABSTRACT: We present Herschel/HIFI observations of the fundamental rotational transitions of ortho- and para-H$_2^{16}$O and H$_2^{18}$O in absorption towards Sagittarius~B2(M) and W31C. The ortho/para ratio in water in the foreground clouds on the line of sight towards these bright continuum sources is generally consistent with the statistical high-temperature ratio of 3, within the observational uncertainties. However, somewhat unexpectedly, we derive a low ortho/para ratio of $2.35 \pm 0.35$, corresponding to a spin temperature of $\sim$27~K, towards Sagittarius~B2(M) at velocities of the expanding molecular ring. Water molecules in this region appear to have formed with, or relaxed to, an ortho/para ratio close to the value corresponding to the local temperature of the gas and dust.
    Astronomy and Astrophysics 07/2010; 521. DOI:10.1051/0004-6361/201015072 · 4.48 Impact Factor
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    ABSTRACT: We report the detection of absorption by interstellar hydroxyl cations and water cations, along the sight-line to the bright continuum source W49N. We have used Herschel's HIFI instrument, in dual beam switch mode, to observe the 972 GHz N = 1 - 0 transition of OH+ and the 1115 GHz 1(11) - 0(00) transition of ortho-H2O+. The resultant spectra show absorption by ortho-H2O+, and strong absorption by OH+, in foreground material at velocities in the range 0 to 70 km/s with respect to the local standard of rest. The inferred OH+/H2O+ abundance ratio ranges from ~ 3 to ~ 15, implying that the observed OH+ arises in clouds of small molecular fraction, in the 2 - 8% range. This conclusion is confirmed by the distribution of OH+ and H2O+ in Doppler velocity space, which is similar to that of atomic hydrogen, as observed by means of 21 cm absorption measurements, and dissimilar from that typical of other molecular tracers. The observed OH+/H abundance ratio of a few E-8 suggests a cosmic ray ionization rate for atomic hydrogen of (0.6 - 2.4) E-16 s-1, in good agreement with estimates inferred previously for diffuse clouds in the Galactic disk from observations of interstellar H3+ and other species. Comment: Accepted for publication in A&A Letters
    Astronomy and Astrophysics 07/2010; 521. DOI:10.1051/0004-6361/201015077 · 4.48 Impact Factor
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    ABSTRACT: We present spectrally resolved observations of triatomic carbon (C3) in several ro-vibrational transitions between the vibrational ground state and the low-energy nu2 bending mode at frequencies between 1654-1897 GHz along the sight-lines to the submillimeter continuum sources W31C and W49N, using Herschel's HIFI instrument. We detect C3 in absorption arising from the warm envelope surrounding the hot core, as indicated by the velocity peak position and shape of the line profile. The sensitivity does not allow to detect C3 absorption due to diffuse foreground clouds. From the column densities of the rotational levels in the vibrational ground state probed by the absorption we derive a rotation temperature (T_rot) of ~50--70 K, which is a good measure of the kinetic temperature of the absorbing gas, as radiative transitions within the vibrational ground state are forbidden. It is also in good agreement with the dust temperatures for W31C and W49N. Applying the partition function correction based on the derived T_rot, we get column densities N(C3) ~7-9x10^{14} cm^{-2} and abundance x(C3)~10^{-8} with respect to H2. For W31C, using a radiative transfer model including far-infrared pumping by the dust continuum and a temperature gradient within the source along the line of sight we find that a model with x(C3)=10^{-8}, T_kin=30-50 K, N(C3)=1.5 10^{15} cm^{-2} fits the observations reasonably well and provides parameters in very good agreement with the simple excitation analysis. Comment: Accepted for publication in Astronomy and Astrophysics (HIFI first results issue)
    Astronomy and Astrophysics 07/2010; 521. DOI:10.1051/0004-6361/201015095 · 4.48 Impact Factor

Publication Stats

3k Citations
488.07 Total Impact Points

Institutions

  • 2010–2014
    • Aix-Marseille Université
      • Laboratory of Astrophysics of Marseille (UMR 7326 LAM)
      Marsiglia, Provence-Alpes-Côte d'Azur, France
  • 2011
    • Pierre and Marie Curie University - Paris 6
      • Institut d'astrophysique de Paris
      Paris, Ile-de-France, France
  • 2008
    • Space Telescope Science Institute
      Baltimore, Maryland, United States
  • 1983–2008
    • French National Centre for Scientific Research
      • Institut d'astrophysique spatiale (IAS)
      Paris, Ile-de-France, France
  • 2006
    • European Space Agency
      Lutetia Parisorum, Île-de-France, France
  • 2003
    • Princeton University
      • Department of Astrophysical Sciences
      Princeton, New Jersey, United States
  • 2002
    • Chalmers University of Technology
      Goeteborg, Västra Götaland, Sweden
  • 1994
    • Université Paris-Sud 11
      Orsay, Île-de-France, France
  • 1993
    • Observatoire de Paris
      Lutetia Parisorum, Île-de-France, France
  • 1992
    • Ecole Normale Supérieure de Paris
      • Laboratoire de Radioastronomie
      Lutetia Parisorum, Île-de-France, France
  • 1988
    • Johns Hopkins University
      • Department of Physics and Astronomy
      Baltimore, MD, United States
  • 1987
    • University of Catania
      Catania, Sicily, Italy
    • University of Tuebingen
      Tübingen, Baden-Württemberg, Germany
  • 1986
    • Institut d'astrophysique de Paris
      Lutetia Parisorum, Île-de-France, France
  • 1984–1986
    • The Ecological Society of America
      Florida, United States
  • 1985
    • University of Chicago
      • Department of Astronomy and Astrophysics
      Chicago, Illinois, United States