References of "Wilhelm, R"
     in
Bookmark and Share    
Full Text
Peer Reviewed
See detailPerformance study of ground-based infrared Bracewell interferometers. Application to the detection of exozodiacal dust disks with GENIE
Absil, Olivier ULg; den Hartog, R.; Gondoin, P. et al

in Astronomy and Astrophysics (2006), 448

Nulling interferometry, a powerful technique for high-resolution imaging of the close neighbourhood of bright astrophysical objets, is currently considered for future space missions such as Darwin or the ... [more ▼]

Nulling interferometry, a powerful technique for high-resolution imaging of the close neighbourhood of bright astrophysical objets, is currently considered for future space missions such as Darwin or the Terrestrial Planet Finder Interferometer (TPF-I), both aiming at Earth-like planet detection and characterization. Ground-based nulling interferometers are being studied for both technology demonstration and scientific preparation of the Darwin/TPF-I missions through a systematic survey of circumstellar dust disks around nearby stars. In this paper, we investigate the influence of atmospheric turbulence on the performance of ground-based nulling instruments, and deduce the major design guidelines for such instruments. End-to-end numerical simulations allow us to estimate the performance of the main subsystems and thereby the actual sensitivity of the nuller to faint exozodiacal disks. Particular attention is also given to the important question of stellar leakage calibration. This study is illustrated in the context of GENIE, the Ground-based European Nulling Interferometer Experiment, to be installed at the VLTI and working in the L' band. We estimate that this instrument will detect exozodiacal clouds as faint as about 50 times the Solar zodiacal cloud, thereby placing strong constraints on the acceptable targets for Darwin/TPF-I. [less ▲]

Detailed reference viewed: 18 (7 ULg)
Full Text
See detailThe prospects of detecting exo-planets with the Ground-based European Nulling Interferometer Experiment (GENIE)
den Hartog, R.; Absil, Olivier ULg; Gondoin, P. et al

in Aime, C.; Vakili, F. (Eds.) Direct Imaging of Exoplanets: Science & Techniques (2006)

The European Space Agency's Darwin and NASA's Terrestrial Planet Finder (TPF) are among the most challenging space science missions ever considered. Their principal objective is to detect Earth-like ... [more ▼]

The European Space Agency's Darwin and NASA's Terrestrial Planet Finder (TPF) are among the most challenging space science missions ever considered. Their principal objective is to detect Earth-like planets around nearby stars and to characterize their atmospheres. Darwin and TPF-I are currently conceived as nulling interferometers with free-flying telescopes. Within the frame of the Darwin program, the ESA and the European Southern Observatory (ESO), supported by European industries and scientific institutes, have performed two parallel Phase A studies of a ground-based nulling interferometry experiment (GENIE) at the site of ESO's Very Large Telescope Interferometer (VLTI) in Paranal, Chile. GENIE will demonstrate several key technologies required for the Darwin mission. Its science objectives include the detection and characterization of dust disks and low-mass companions around nearby stars. These studies have established detailed instrumental designs, in which GENIE will operate in the L' band around 3.8 microns as a single Bracewell nulling or constructive interferometer, using either two Auxiliary or two Unit Telescopes. The studies were supported by detailed numerical simulations which indicated the possibility of detection and low-resolution spectroscopy in nulling mode of extra-solar giant planets (EGPs) with atmospheric temperatures down to 700 K, provided that a proper calibration of instrumental effects is applied. Detection of circumstellar exo-zodiacal (EZ) dust clouds is possible down to 0.5 mJy, with interesting prospects for the characterization of planet-forming disks. [less ▲]

Detailed reference viewed: 2 (0 ULg)
Full Text
See detailCould GENIE detect hot Jupiters?
den Hartog, Roland; Absil, Olivier ULg; Kaltenegger, L. et al

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

The prime objective of GENIE (Ground-based European Nulling Interferometry Experiment) is to obtain experience with the design, construction and operation of an IR nulling interferometer, as a preparation ... [more ▼]

The prime objective of GENIE (Ground-based European Nulling Interferometry Experiment) is to obtain experience with the design, construction and operation of an IR nulling interferometer, as a preparation for the DARWIN/TPF mission. In this context, the detection of a planet orbiting another star would provide an excellent demonstration of nulling interferometry. Doing this through the atmosphere, however, is a formidable task. In this paper we assess the prospects of detecting, with nulling interferometry on ESO's VLT, a Hot Jupiter, a giant planet in a close orbit around its parent star. First we discuss the definition of the optimal target. Then we present a simulated observation of the Tau Bootis system, which suggests that GENIE, in a L'-band single Bracewell configuration, could detect the hot Jupiter in a few hours time with a signal-to-noise ratio of up to ~80. Although there are strong requirements on the control-loop performance, background subtraction and accuracy of the photometry calibration, we conclude that at present there do not seem to be fundamental problems that would prevent GENIE from detecting hot Jupiters. Hence the answer to the question in the title is yes. [less ▲]

Detailed reference viewed: 5 (0 ULg)
Full Text
See detailThe Ground-based European Nulling Interferometry Experiment (DARWIN-GENIE)
Gondoin, P.; Absil, Olivier ULg; den Hartog, R. et al

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

Detailed reference viewed: 7 (0 ULg)
Full Text
See detailGENIEsim: the GENIE simulation software
Absil, Olivier ULg; den Hartog, R.; Erd, C. et al

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

GENIEsim, the GENIE simulation software, is an IDL-based code to simulate future observations with the Ground-based European Nulling Interferometer Experiment, which should be commissioned on the Very ... [more ▼]

GENIEsim, the GENIE simulation software, is an IDL-based code to simulate future observations with the Ground-based European Nulling Interferometer Experiment, which should be commissioned on the Very Large Telescope Interferometer (VLTI) in 2007. The code simulates operation in the mid-infrared (L' and N bands) and includes all major noise sources. The atmospheric turbulence is described by a Kolmogorov power spectrum, from which random time series are computed for perturbations to the optical paths. The effect of turbulence is reduced by means of control loops, which are either included in the VLTI facility (MACAO, PRIMA) or specific to the GENIE instrument. The output of GENIEsim is a time series of fluxes computed by integration of a source field multiplied by the GENIE transmission map, projected onto the plane of the sky. Simulations have already allowed to identify critical points in the design of the instrument, such as OPD and dispersion control, calibration of stellar leakage and background subtraction. [less ▲]

Detailed reference viewed: 10 (0 ULg)
Full Text
See detailCan GENIE characterize debris disks around nearby stars?
Absil, Olivier ULg; Kaltenegger, L.; Eiroa, C. et al

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

The Ground-based European Nulling Interferometer Experiment will combine the light collected by two or more VLT telescopes and make them interfere in a destructive way, thereby revealing the close ... [more ▼]

The Ground-based European Nulling Interferometer Experiment will combine the light collected by two or more VLT telescopes and make them interfere in a destructive way, thereby revealing the close neighborhood of nearby stars. Operating at mid-infrared wavelengths, GENIE will be particularly sensible to warm circumstellar dust. This paper presents simulated observations of the debris disk around the nearby A2V star zeta Leporis obtained with the GENIE simulation software. Parameters such as inclination, density power-law exponent and inner radius can be retrieved with a relative precision of 1% or better using only six observations of 15 minutes. In the context of the DARWIN/TPF mission, warm circumstellar dust could be a serious limitation to the detection of Earth-like exoplanets. This paper shows that GENIE will detect disks as faint as 23 times our local zodiacal cloud around Sun-like stars at 10 pc, and will thus allow to discard unsuitable targets for DARWIN/TPF. [less ▲]

Detailed reference viewed: 7 (0 ULg)
Full Text
See detailThe Darwin Ground-based European Nulling Interferometry Experiment
Gondoin, P.; Absil, Olivier ULg; Fridlund, M. et al

in Lacoste, H. (Ed.) GENIE - DARWIN Workshop - Hunting for Planets (2003, March 01)

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

Darwin is one of the most challenging space pro jects ever considered by the European Space Agency (ESA). Its principal ob jectives are to detect Earth-like planets around nearby stars and to characterise 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 o -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 ob jectives and the status of the project. [less ▲]

Detailed reference viewed: 1 (0 ULg)