References of "Gondoin, Philippe"
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See detailThe Search for Worlds Like Our Own
Fridlund, Malcolm; Eiroa, Carlos; Henning, Thomas et al

in Astrobiology (2010), 10(1), 5-17

The direct detection of Earth-like exoplanets orbiting nearby stars and the characterization of such planets -- particularly, their evolution, their atmospheres, and their ability to host life ... [more ▼]

The direct detection of Earth-like exoplanets orbiting nearby stars and the characterization of such planets -- particularly, their evolution, their atmospheres, and their ability to host life -- constitute a significant problem. The quest for other worlds as abodes of life has been one of mankind's great questions for several millennia. For instance, as stated by Epicurus 300 BC: Other worlds, with plants and other living things, some of them similar and some of them different from ours, must exist. Demokritos from Abdera (460-370 BC), the man who invented the concept of indivisible small parts - atoms - also held the belief that other worlds exist around the stars and that some of these worlds may be inhabited by life-forms. The idea of the plurality of worlds and of life on them has since been held by scientists like Johannes Kepler and William Herschel, among many others. Here, one must also mention Giordano Bruno. Born in 1548, Bruno studied in France and came into contact with the teachings of Nicolas Copernicus. He wrote the book De l'Infinito, Universo e Mondi in 1584, in which he claimed that the Universe was infinite, that it contained an infinite amount of worlds like Earth, and that these worlds were inhabited by intelligent beings. At the time, this was extremely controversial, and eventually Bruno was arrested by the church and burned at the stake in Rome in 1600, as a heretic, for promoting this and other equally confrontational issues (though it is unclear exactly which idea was the one that ultimately brought him to his end). In all the aforementioned cases, the opinions and results were arrived at through reasoning--not by experiment. We have only recently acquired the technological capability to observe planets orbiting stars other than 6our Sun; acquisition of this capability has been a remarkable feat of our time. We show in this introduction to the Habitability Primer that mankind is at the dawning of an age when, by way of the scientific method and 21st-century technology, we will be able to answer this fascinating controversial issue that has persisted for at least 2500 years. [less ▲]

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See detailGENIE: High-Resolution Study of Debris Disks
Absil, Olivier ULg; Augereau, Jean-Charles; Den Hartog, Roland et al

in Richichi, A.; Delplancke, F.; Paresce, F. (Eds.) et al The Power of Optical/IR Interferometry: Recent Scientific Results and 2nd Generation Instrumentation (2008)

GENIE, the Ground-based European Nulling Interferometer Experiment, will combine the lights collected in the L’ band by two VLT telescopes in a destructive way, thereby revealing the thermal and/or ... [more ▼]

GENIE, the Ground-based European Nulling Interferometer Experiment, will combine the lights collected in the L’ band by two VLT telescopes in a destructive way, thereby revealing the thermal and/or scattered emission of faint objects in the close neighbourhood of the target star. A prime scientific goal for GENIE thus consists in the detection and characterization of debris disks around nearby Vega-type stars. Thanks to its high angular resolution and operating wavelength (3.8 µm), GENIE will be particularly sensitive to the thermal emission from the warm dust standing within a few AU from the star, a part of the disks which is not accessible with current detection methods (IR photometric excesses, sub-millimeter imaging, …). In this paper, we investigate the capabilities of GENIE to detect and characterize the physical parameters of the debris disk around zeta Leporis, a prototypical Vega-type star suspected to harbour a warm dust component in its debris disk (Fajardo-Acosta et al., AJ 115, 2101). This study is then extended to the detection of faint exozodiacal disks around typical Darwin/TPF targets, thereby demonstrating the very high potential of GENIE in the field of high-contrast imaging. [less ▲]

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See detailInfluence of atmospheric turbulence on the performance and design of GENIE
Absil, Olivier ULg; den Hartog, Roland; Gondoin, Philippe et al

in Traub, Wesley; Monnier, John; Schöller, Markus (Eds.) New Frontiers in Stellar Interferometry (2004, October 01)

Two competitive design studies for the Ground-based European Nulling Interferometer Experiment (GENIE) have been initiated by the European Space Agency and the European Southern Observatory in November ... [more ▼]

Two competitive design studies for the Ground-based European Nulling Interferometer Experiment (GENIE) have been initiated by the European Space Agency and the European Southern Observatory in November 2003. The GENIE instrument will most probably consist of a two-telescope Bracewell interferometer, using the 8-m Unit Telescopes and/or the 1.8-m Auxiliary Telescopes of the VLTI, and working in the infrared L' band (3.5 - 4.1 microns). A critical issue affecting the overall performance of the instrument is its capability to compensate for the phase and intensity fluctuations produced by the atmospheric turbulence. In this paper, we present the basic principles of phase and intensity control by means of real-time servo loops in the context of GENIE. We then propose a preliminary design for these servo loops and estimate their performance using GENIEsim, the science simulation software for the GENIE instrument. [less ▲]

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See detailThermal background fluctuations at 10 micron measured with VLTI/MIDI
Absil, Olivier ULg; Bakker, Eric; Schoeller, Markus et al

in Traub, Wesley; Monnier, John; Schöller, Markus (Eds.) New Frontiers in Stellar Interferometry (2004, October 01)

We present an experiment to measure the thermal background level and its fluctuations with the European Southern Observatory (ESO) Very Large Telescope Interferometer (VLTI). The Mid Infrared Instrument ... [more ▼]

We present an experiment to measure the thermal background level and its fluctuations with the European Southern Observatory (ESO) Very Large Telescope Interferometer (VLTI). The Mid Infrared Instrument (MIDI) operating between 8 and 12 micron was used in both dispersed and non-dispersed modes. By using an interferometric instrument, in non-interferometric mode, we probe the same optical path as can be expected for other infrared interferometric instruments, e.g. GENIE and MIDI itself. Most of the infrared thermal background detected with MIDI originates from the VLTI infrastructure. This can be attributed to the absence of a pupil re-imaging mirror. Only for a small region around the optical axis of the system the signal from the VLTI infrastructure can be considered small and the atmospheric background fluctuations can be characterized. The fluctuations of the thermal emission are described in terms of their power spectral densities (PSD). We have identified two regions in the PSD. For the low frequency range (0-10 Hz) the fluctuations are dominated by the Earth atmosphere. The slope of the log-log PSD is close to -1. For the high frequency (larger than 10 Hz) range the fluctuations are due to photon noise and the PSD flattens off. Many narrow peaks are present in the PSD. Peaks at 1 and 50 Hz occur in almost all data sets and are identified as the effects of the MIDI closed cycle cooler and the power lines respectively. Other peaks at 10 and 30 Hz, as well as peaks above 50 Hz, are assumed to be VLTI or MIDI-specific frequencies. [less ▲]

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See detailCharacterisation of disks around YSOs with GENIE
Kaltenegger, Lisa; Absil, Olivier ULg; Eiroa, Carlos et al

in Fridlund, Malcolm; Henning, Thomas (Eds.) Towards Other Earths: DARWIN/TPF and the Search for Extrasolar Terrestrial Planets (2003, October 01)

Recent interferometric observations show that the interfered near-IR size of the circumstellar material around Young Stellar Object (YSO) are larger than those expected from accretion disk models. There ... [more ▼]

Recent interferometric observations show that the interfered near-IR size of the circumstellar material around Young Stellar Object (YSO) are larger than those expected from accretion disk models. There are currently different models that account for the excess IR emission of Young Stellar Objects (YSO). At the same time, the answers to many questions on the evolutionary status and the origin of the activity and variability depend critically on the relative importance of circumstellar distribution of material in disks or envelopes at different spatial scales. Operating at mid-infrared wavelengths, the Ground-based European Nulling Interferometer Experiment (GENIE) will be particularly sensitive to warm circumstellar dust and will thus provide the opportunity to characterize dust disks around YSOs. Observations with GENIE will enable us to investigate the properties of the circumstellar dust, which are responsible for the excess near-infrared fluxes. The nulling of the central star will bring out the disk in much more detail and hence put stronger constraints on these models. [less ▲]

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See detailDarwin ground-based European nulling interferometer experiment (GENIE)
Gondoin, Philippe; Absil, Olivier ULg; Fridlund, C V Malcolm et al

in Traub, Wesley (Ed.) Interferometry for Optical Astronomy II (2003, February 01)

Darwin is one of the most challenging space projects ever considered by the European Space Agency (ESA). Its principal objectives are to detect Earth-like planets around nearby stars and to characterize ... [more ▼]

Darwin is one of the most challenging space projects ever considered by the European Space Agency (ESA). Its principal objectives are to detect Earth-like planets around nearby stars and to characterize their atmospheres. Darwin is conceived as a space "nulling interferometer" which makes use of on-axis destructive interferences to extinguish the stellar light while keeping the off-axis signal of the orbiting planet. Within the frame of the Darwin program, the European Space Agency (ESA) and the European Southern Observatory (ESO) intend to build a ground-based technology demonstrator called GENIE (Ground based European Nulling Interferometry Experiment). Such a ground-based demonstrator built around the Very Large Telescope Interferometer (VLTI) in Paranal will test some of the key technologies required for the Darwin Infrared Space Interferometer. It will demonstrate that nulling interferometry can be achieved in a broad mid-IR band as a precursor to the next phase of the Darwin program. The present paper will describe the objectives and the status of the project. [less ▲]

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See detailPSF modeling of the XMM flight mirror modules
Stockman, Yvan ULg; Houbrechts, Yvette ULg; Nazé, Yaël ULg et al

in Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series (1999, October 01)

In the frame of XMM testing, all the mirror modules have been illuminated by a vertical EUV collimated beam a the Centre Spatial de Liege. A mirror module consists in 58 co- focal and co-axial Wolter I ... [more ▼]

In the frame of XMM testing, all the mirror modules have been illuminated by a vertical EUV collimated beam a the Centre Spatial de Liege. A mirror module consists in 58 co- focal and co-axial Wolter I mirrors. Up to now the images obtained at CSL have been used to assess the Mirror Module optical performances in a flight representative configuration, and also to verify the impact of the thermal environmental and vibration test on the optical performance. Due to the highly complex design of the Mirror Modules, simulating XMM images in details is very difficult. The Point Spread Function of some of the mirror modules presents slight asymmetry. In the facility design study, it has been demonstrated that the diffraction impact at 58.4 nm is negligible with respect to the half energy width mirror module specification. Presently all the mirror modules are better than 165 arcsec. This paper presents first the diffraction contribution on the image. In a second step a point spread function is built by using the metrological mirror shell data. EUV images are then analyzed to evaluate the impact of the mirror interface structure integration process on the PSF. An analytical model of the measured EUV pSF is developed. The modelization technique is applied to simulate in-orbit image. Finally the different modelizations are evaluated and compared. [less ▲]

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