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 References of "Mennesson, B"      in Complete repository Arts & humanities   Archaeology   Art & art history   Classical & oriental studies   History   Languages & linguistics   Literature   Performing arts   Philosophy & ethics   Religion & theology   Multidisciplinary, general & others Business & economic sciences   Accounting & auditing   Production, distribution & supply chain management   Finance   General management & organizational theory   Human resources management   Management information systems   Marketing   Strategy & innovation   Quantitative methods in economics & management   General economics & history of economic thought   International economics   Macroeconomics & monetary economics   Microeconomics   Economic systems & public economics   Social economics   Special economic topics (health, labor, transportation…)   Multidisciplinary, general & others Engineering, computing & technology   Aerospace & aeronautics engineering   Architecture   Chemical engineering   Civil engineering   Computer science   Electrical & electronics engineering   Energy   Geological, petroleum & mining engineering   Materials science & engineering   Mechanical engineering   Multidisciplinary, general & others Human health sciences   Alternative medicine   Anesthesia & intensive care   Cardiovascular & respiratory systems   Dentistry & oral medicine   Dermatology   Endocrinology, metabolism & nutrition   Forensic medicine   Gastroenterology & hepatology   General & internal medicine   Geriatrics   Hematology   Immunology & infectious disease   Laboratory medicine & medical technology   Neurology   Oncology   Ophthalmology   Orthopedics, rehabilitation & sports medicine   Otolaryngology   Pediatrics   Pharmacy, pharmacology & toxicology   Psychiatry   Public health, health care sciences & services   Radiology, nuclear medicine & imaging   Reproductive medicine (gynecology, andrology, obstetrics)   Rheumatology   Surgery   Urology & nephrology   Multidisciplinary, general & others Law, criminology & political science   Civil law   Criminal law & procedure   Criminology   Economic & commercial law   European & international law   Judicial law   Metalaw, Roman law, history of law & comparative law   Political science, public administration & international relations   Public law   Social law   Tax law   Multidisciplinary, general & others Life sciences   Agriculture & agronomy   Anatomy (cytology, histology, embryology...) & physiology   Animal production & animal husbandry   Aquatic sciences & oceanology   Biochemistry, biophysics & molecular biology   Biotechnology   Entomology & pest control   Environmental sciences & ecology   Food science   Genetics & genetic processes   Microbiology   Phytobiology (plant sciences, forestry, mycology...)   Veterinary medicine & animal health   Zoology   Multidisciplinary, general & others Physical, chemical, mathematical & earth Sciences   Chemistry   Earth sciences & physical geography   Mathematics   Physics   Space science, astronomy & astrophysics   Multidisciplinary, general & others Social & behavioral sciences, psychology   Animal psychology, ethology & psychobiology   Anthropology   Communication & mass media   Education & instruction   Human geography & demography   Library & information sciences   Neurosciences & behavior   Regional & inter-regional studies   Social work & social policy   Sociology & social sciences   Social, industrial & organizational psychology   Theoretical & cognitive psychology   Treatment & clinical psychology   Multidisciplinary, general & others     Showing results 1 to 20 of 31 1 2     Space-based infrared interferometry to study exoplanetary atmospheresDefrere, Denis ; Léger, A.; Absil, Olivier et alin Experimental Astronomy: Astrophysical Instrumentation and Methods (in press), 1801The quest for other habitable worlds and the search for life among them are major goals of modern astronomy. One way to make progress towards these goals is to obtain high-quality spectra of a large ... [more ▼]The quest for other habitable worlds and the search for life among them are major goals of modern astronomy. One way to make progress towards these goals is to obtain high-quality spectra of a large number of exoplanets over a broad range of wavelengths. While concepts currently investigated in the United States are focused on visible/NIR wavelengths, where the planets are probed in reflected light, a compelling alternative to characterize planetary atmospheres is the mid-infrared waveband (5-20um). Indeed, mid-infrared observations provide key information on the presence of an atmosphere, the surface conditions (e.g., temperature, pressure, habitability), and the atmospheric composition in important species such as H2O, CO2, O3, CH4, and N2O. This information is essential to investigate the potential habitability of exoplanets and to make progress towards the search for life in the universe. Obtaining high-quality mid-infrared spectra of exoplanets from the ground is however extremely challenging due to the overwhelming brightness and turbulence of Earth's atmosphere. In this paper, we present a concept of space-based mid-infrared interferometer that can tackle this observing challenge and discuss the main technological developments required to launch such a sophisticated instrument. [less ▲]Detailed reference viewed: 32 (0 ULiège) The path towards high-contrast imaging with the VLTI: the Hi-5 projectDefrere, Denis ; Absil, Olivier ; Berger, J.-P. et alin Experimental Astronomy: Astrophysical Instrumentation and Methods (in press), 1801The development of high-contrast capabilities has long been recognized as one of the top priorities for the VLTI. As of today, the VLTI routinely achieves contrasts of a few 10$^{-3}$ in the near-infrared ... [more ▼]The development of high-contrast capabilities has long been recognized as one of the top priorities for the VLTI. As of today, the VLTI routinely achieves contrasts of a few 10$^{-3}$ in the near-infrared with PIONIER (H band) and GRAVITY (K band). Nulling interferometers in the northern hemisphere and non-redundant aperture masking experiments have, however, demonstrated that contrasts of at least a few 10$^{-4}$ are within reach using specific beam combination and data acquisition techniques. In this paper, we explore the possibility to reach similar or higher contrasts on the VLTI. After reviewing the state-of-the-art in high-contrast infrared interferometry, we discuss key features that made the success of other high-contrast interferometric instruments (e.g., integrated optics, nulling, closure phase, and statistical data reduction) and address possible avenues to improve the contrast of the VLTI by at least one order of magnitude. In particular, we discuss the possibility to use integrated optics, proven in the near-infrared, in the thermal near-infrared (L and M bands, 3-5 $\mu$m), a sweet spot to image and characterize young extra-solar planetary systems. Finally, we address the science cases of a high-contrast VLTI imaging instrument and focus particularly on exoplanet science (young exoplanets, planet formation, and exozodiacal disks), stellar physics (fundamental parameters and multiplicity), and extragalactic astrophysics (active galactic nuclei and fundamental constants). Synergies and scientific preparation for other potential future instruments such as the Planet Formation Imager are also briefly discussed. [less ▲]Detailed reference viewed: 8 (0 ULiège) The LBTI Fizeau imager – II. Sensitivity of the PSF and the MTF to adaptive optics errors and to piston errorsPatru, F.; Esposito, S.; Puglisi, A. et alin Monthly Notices of the Royal Astronomical Society (2017), 472We show numerical simulations with monochromatic light in the visible for the LBTI Fizeau imager, including opto-dynamical aberrations due here to adaptive optics (AO) errors and to differential piston ... [more ▼]We show numerical simulations with monochromatic light in the visible for the LBTI Fizeau imager, including opto-dynamical aberrations due here to adaptive optics (AO) errors and to differential piston fluctuations, while other errors have been neglected. The achievable Strehl by the LBTI using two AO is close to the Strehl provided by a single standalone AO system, as long as other differential wavefront errors are mitigated. The LBTI Fizeau imager is primarily limited by the AO performance and by the differential piston/tip–tilt errors. Snapshots retain high-angular resolution and high-contrast imaging information by freezing the fringes against piston errors. Several merit functions have been critically evaluated in order to characterize point spread functions and the modulation transfer functions for high-contrast imaging applications. The LBTI Fizeau mode can provide an image quality suitable for standard science cases (i.e. a Strehl above 70 per cent) by performing both at a time: an AO correction better than ≈λ/18 RMS for both short and long exposures, and a piston correction better than ≈λ/8 RMS for long exposures or simply below the coherence length for short exposures. Such results, which can be applied to any observing wavelength, suggest that AO and piston control at the LBTI would already improve the contrast at near- and mid-infrared wavelengths. Therefore, the LBTI Fizeau imager can be used for high-contrast imaging, providing a high-Strehl regime (by both AO systems), a cophasing mode (by a fringe tracker) and a burst mode (by a fast camera) to record fringed speckles in short exposures. [less ▲]Detailed reference viewed: 18 (1 ULiège) The LBTI Fizeau imager - I. Fundamental gain in high-contrast imagingPatru, F.; Esposito, S.; Puglisi, A. et alin Monthly Notices of the Royal Astronomical Society (2017), 472We show by numerical simulations a fundamental gain in contrast when combining coherently monochromatic light from two adaptive optics (AO) telescopes instead of using a single stand-alone AO telescope ... [more ▼]We show by numerical simulations a fundamental gain in contrast when combining coherently monochromatic light from two adaptive optics (AO) telescopes instead of using a single stand-alone AO telescope, assuming efficient control and acquisition systems at high speed. A contrast gain map is defined as the normalized point spread functions (PSFs) ratio of a single Large Binocular Telescope (LBT) aperture over the dual Large Binocular Telescope Interferometer (LBTI) aperture in Fizeau mode. The global gain averaged across the AO-corrected field of view is improved by a factor of 2 in contrast in long exposures and by a factor of 10 in contrast in short exposures (i.e. in exposures, respectively, longer or shorter than the coherence time). The fringed speckle halo in short exposures contains not only high-angular resolution information, as stated by speckle imaging and speckle interferometry, but also high-contrast imaging information. A high-gain zone is further produced in the valleys of the PSF formed by the dark Airy rings and/or the dark fringes. Earth rotation allows us to exploit various areas in the contrast gain map. A huge-contrast gain in narrow zones can be achieved when both a dark fringe and a dark ring overlap on to an exoplanet. Compared to a single 8-m LBT aperture, the 23-m LBTI Fizeau imager can provide a gain in sensitivity (by a factor of 4), a gain in angular resolution (by a factor of 3) and, as well, a gain in raw contrast (by a factor of 2-1000 varying over the AO-corrected field of view). [less ▲]Detailed reference viewed: 24 (5 ULiège) Overview of LBTI: a multipurpose facility for high spatial resolution observationsHinz, P. M.; Defrere, Denis ; Skemer, A. et alin Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series (2016, August 01)The Large Binocular Telescope Interferometer (LBTI) is a high spatial resolution instrument developed for coherent imaging and nulling interferometry using the 14.4 m baseline of the 2×8.4 m LBT. The ... [more ▼]The Large Binocular Telescope Interferometer (LBTI) is a high spatial resolution instrument developed for coherent imaging and nulling interferometry using the 14.4 m baseline of the 2×8.4 m LBT. The unique telescope design, comprising of the dual apertures on a common elevation-azimuth mount, enables a broad use of observing modes. The full system is comprised of dual adaptive optics systems, a near-infrared phasing camera, a 1-5 μm camera (called LMIRCam), and an 8-13 μm camera (called NOMIC). The key program for LBTI is the Hunt for Observable Signatures of Terrestrial planetary Systems (HOSTS), a survey using nulling interferometry to constrain the typical brightness from exozodiacal dust around nearby stars. Additional observations focus on the detection and characterization of giant planets in the thermal infrared, high spatial resolution imaging of complex scenes such as Jupiter's moon, Io, planets forming in transition disks, and the structure of active Galactic Nuclei (AGN). Several instrumental upgrades are currently underway to improve and expand the capabilities of LBTI. These include: Improving the performance and limiting magnitude of the parallel adaptive optics systems; quadrupling the field of view of LMIRcam (increasing to 20"x20"); adding an integral field spectrometry mode; and implementing a new algorithm for path length correction that accounts for dispersion due to atmospheric water vapor. We present the current architecture and performance of LBTI, as well as an overview of the upgrades. [less ▲]Detailed reference viewed: 12 (1 ULiège) Enabling the direct detection of earth-sized exoplanets with the LBTI HOSTS project: a progress reportDanchi, W.; Bailey, V.; Bryden, G. et alin Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series (2016, August 01)NASA has funded a project called the Hunt for Observable Signatures of Terrestrial Systems (HOSTS) to survey nearby solar type stars to determine the amount of warm zodiacal dust in their habitable zones ... [more ▼]NASA has funded a project called the Hunt for Observable Signatures of Terrestrial Systems (HOSTS) to survey nearby solar type stars to determine the amount of warm zodiacal dust in their habitable zones. The goal is not only to determine the luminosity distribution function but also to know which individual stars have the least amount of zodiacal dust. It is important to have this information for future missions that directly image exoplanets as this dust is the main source of astrophysical noise for them. The HOSTS project utilizes the Large Binocular Telescope Interferometer (LBTI), which consists of two 8.4-m apertures separated by a 14.4-m baseline on Mt. Graham, Arizona. The LBTI operates in a nulling mode in the mid-infrared spectral window (8-13 μm), in which light from the two telescopes is coherently combined with a 180 degree phase shift between them, producing a dark fringe at the location of the target star. In doing so the starlight is greatly reduced, increasing the contrast, analogous to a coronagraph operating at shorter wavelengths. The LBTI is a unique instrument, having only three warm reflections before the starlight reaches cold mirrors, giving it the best photometric sensitivity of any interferometer operating in the mid-infrared. It also has a superb Adaptive Optics (AO) system giving it Strehl ratios greater than 98% at 10 μm. In 2014 into early 2015 LBTI was undergoing commissioning. The HOSTS project team passed its Operational Readiness Review (ORR) in April 2015. The team recently published papers on the target sample, modeling of the nulled disk images, and initial results such as the detection of warm dust around η Corvi. Recently a paper was published on the data pipeline and on-sky performance. An additional paper is in preparation on β Leo. We will discuss the scientific and programmatic context for the LBTI project, and we will report recent progress, new results, and plans for the science verification phase that started in February 2016, and for the survey. [less ▲]Detailed reference viewed: 17 (0 ULiège) Nulling Data Reduction and On-sky Performance of the Large Binocular Telescope InterferometerDefrere, Denis ; Hinz, P. M.; Mennesson, B. et alin Astrophysical Journal (2016), 824The Large Binocular Telescope Interferometer (LBTI) is a versatile instrument designed for high angular resolution and high-contrast infrared imaging (1.5-13 μm). In this paper, we focus on the mid ... [more ▼]The Large Binocular Telescope Interferometer (LBTI) is a versatile instrument designed for high angular resolution and high-contrast infrared imaging (1.5-13 μm). In this paper, we focus on the mid-infrared (8-13 μm) nulling mode and present its theory of operation, data reduction, and on-sky performance as of the end of the commissioning phase in 2015 March. With an interferometric baseline of 14.4 m, the LBTI nuller is specifically tuned to resolve the habitable zone of nearby main-sequence stars, where warm exozodiacal dust emission peaks. Measuring the exozodi luminosity function of nearby main-sequence stars is a key milestone to prepare for future exo-Earth direct imaging instruments. Thanks to recent progress in wavefront control and phase stabilization, as well as in data reduction techniques, the LBTI demonstrated in 2015 February a calibrated null accuracy of 0.05% over a 3 hr long observing sequence on the bright nearby A3V star β Leo. This is equivalent to an exozodiacal disk density of 15-30 zodi for a Sun-like star located at 10 pc, depending on the adopted disk model. This result sets a new record for high-contrast mid-infrared interferometric imaging and opens a new window on the study of planetary systems. [less ▲]Detailed reference viewed: 33 (13 ULiège) Models of the η Corvi Debris Disk from the Keck Interferometer, Spitzer, and HerschelLebreton, J.; Beichman, C.; Bryden, G. et alin Astrophysical Journal (2016), 817Debris disks are signposts of analogs to small-body populations of the solar system, often, however, with much higher masses and dust production rates. The disk associated with the nearby star η Crv is ... [more ▼]Debris disks are signposts of analogs to small-body populations of the solar system, often, however, with much higher masses and dust production rates. The disk associated with the nearby star η Crv is especially striking, as it shows strong mid- and far-infrared excesses despite an age of ∼1.4 Gyr. We undertake constructing a consistent model of the system that can explain a diverse collection of spatial and spectral data. We analyze Keck Interferometer Nuller measurements and revisit Spitzer and additional spectrophotometric data, as well as resolved Herschel images, to determine the dust spatial distribution in the inner exozodi and in the outer belt. We model in detail the two-component disk and the dust properties from the sub-AU scale to the outermost regions by fitting simultaneously all measurements against a large parameter space. The properties of the cold belt are consistent with a collisional cascade in a reservoir of ice-free planetesimals at 133 AU. It shows marginal evidence for asymmetries along the major axis. KIN enables us to establish that the warm dust consists of a ring that peaks between 0.2 and 0.8 AU. To reconcile this location with the ∼400 K dust temperature, very high albedo dust must be invoked, and a distribution of forsterite grains starting from micron sizes satisfies this criterion, while providing an excellent fit to the spectrum. We discuss additional constraints from the LBTI and near-infrared spectra, and we present predictions of what James Webb Space Telescope can unveil about this unusual object and whether it can detect unseen planets. [less ▲]Detailed reference viewed: 15 (3 ULiège) Simultaneous Water Vapor and Dry Air Optical Path Length Measurements and Compensation with the Large Binocular Telescope InterferometerDefrere, Denis ; Hinz, P.; Downey, E. et alin Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series (2016)The Large Binocular Telescope Interferometer uses a near-infrared camera to measure the optical path length variations between the two AO-corrected apertures and provide high-angular resolution ... [more ▼]The Large Binocular Telescope Interferometer uses a near-infrared camera to measure the optical path length variations between the two AO-corrected apertures and provide high-angular resolution observations for all its science channels (1.5-13 microns). There is however a wavelength dependent component to the atmospheric turbulence, which can introduce optical path length errors when observing at a wavelength different from that of the fringe sensing camera. Water vapor in particular is highly dispersive and its effect must be taken into account for high-precision infrared interferometric observations as described previously for VLTI/MIDI or the Keck Interferometer Nuller. In this paper, we describe the new sensing approach that has been developed at the LBT to measure and monitor the optical path length fluctuations due to dry air and water vapor separately. After reviewing the current performance of the system for dry air seeing compensation, we present simultaneous H-, K-, and N-band observations that illustrate the feasibility of our feedforward approach to stabilize the path length fluctuations seen by the LBTI nuller. [less ▲]Detailed reference viewed: 23 (7 ULiège) Exoplanet science with the LBTI: instrument status and plansDefrere, Denis ; Hinz, P.; Skemer, A. et alin Shaklan, Stuart (Ed.) Techniques and Instrumentation for Detection of Exoplanets VII (2015, September 16)The Large Binocular Telescope Interferometer (LBTI) is a strategic instrument of the LBT designed for high-sensitivity, high-contrast, and high-resolution infrared (1.5-13 $\mu$m) imaging of nearby ... [more ▼]The Large Binocular Telescope Interferometer (LBTI) is a strategic instrument of the LBT designed for high-sensitivity, high-contrast, and high-resolution infrared (1.5-13 $\mu$m) imaging of nearby planetary systems. To carry out a wide range of high-spatial resolution observations, it can combine the two AO-corrected 8.4-m apertures of the LBT in various ways including direct (non-interferometric) imaging, coronagraphy (APP and AGPM), Fizeau imaging, non-redundant aperture masking, and nulling interferometry. It also has broadband, narrowband, and spectrally dispersed capabilities. In this paper, we review the performance of these modes in terms of exoplanet science capabilities and describe recent instrumental milestones such as first-light Fizeau images (with the angular resolution of an equivalent 22.8-m telescope) and deep interferometric nulling observations. [less ▲]Detailed reference viewed: 30 (10 ULiège) First-light LBT Nulling Interferometric Observations: Warm Exozodiacal Dust Resolved within a Few AU of eta CrvDefrere, Denis ; Hinz, P. M.; Skemer, A. J. et alin Astrophysical Journal (2015), 799We report on the first nulling interferometric observations with the Large Binocular Telescope Interferometer (LBTI), resolving the N' band (9.81-12.41 μm) emission around the nearby main-sequence star η ... [more ▼]We report on the first nulling interferometric observations with the Large Binocular Telescope Interferometer (LBTI), resolving the N' band (9.81-12.41 μm) emission around the nearby main-sequence star η Crv (F2V, 1-2 Gyr). The measured source null depth amounts to 4.40% ± 0.35% over a field-of-view of 140 mas in radius (~2.6 AU for the distance of η Crv) and shows no significant variation over 35° of sky rotation. This relatively low null is unexpected given the total disk to star flux ratio measured by the Spitzer Infrared Spectrograph (IRS; ~23% across the N' band), suggesting that a significant fraction of the dust lies within the central nulled response of the LBTI (79 mas or 1.4 AU). Modeling of the warm disk shows that it cannot resemble a scaled version of the solar zodiacal cloud unless it is almost perpendicular to the outer disk imaged by Herschel. It is more likely that the inner and outer disks are coplanar and the warm dust is located at a distance of 0.5-1.0 AU, significantly closer than previously predicted by models of the IRS spectrum (~3 AU). The predicted disk sizes can be reconciled if the warm disk is not centrosymmetric, or if the dust particles are dominated by very small grains. Both possibilities hint that a recent collision has produced much of the dust. Finally, we discuss the implications for the presence of dust for the distance where the insolation is the same as Earth's (2.3 AU). [less ▲]Detailed reference viewed: 30 (10 ULiège) Constraining the Exozodiacal Luminosity Function of Main-sequence Stars: Complete Results from the Keck Nuller Mid-infrared SurveysMennesson, B.; Millan-Gabet, R.; Serabyn, E. et alin Astrophysical Journal (2014), 797Forty-seven nearby main-sequence stars were surveyed with the Keck Interferometer mid-infrared Nulling instrument (KIN) between 2008 and 2011, searching for faint resolved emission from exozodiacal dust ... [more ▼]Forty-seven nearby main-sequence stars were surveyed with the Keck Interferometer mid-infrared Nulling instrument (KIN) between 2008 and 2011, searching for faint resolved emission from exozodiacal dust. Observations of a subset of the sample have already been reported, focusing essentially on stars with no previously known dust. Here we extend this previous analysis to the whole KIN sample, including 22 more stars with known near- and/or far-infrared excesses. In addition to an analysis similar to that of the first paper of this series, which was restricted to the 8-9 mum spectral region, we present measurements obtained in all 10 spectral channels covering the 8-13 mum instrumental bandwidth. Based on the 8-9 mum data alone, which provide the highest signal-to-noise measurements, only one star shows a large excess imputable to dust emission (eta Crv), while four more show a significant (>3sigma) excess: beta Leo, beta UMa, zeta Lep, and gamma Oph. Overall, excesses detected by KIN are more frequent around A-type stars than later spectral types. A statistical analysis of the measurements further indicates that stars with known far-infrared (lambda >= 70 mum) excesses have higher exozodiacal emission levels than stars with no previous indication of a cold outer disk. This statistical trend is observed regardless of spectral type and points to a dynamical connection between the inner (zodi-like) and outer (Kuiper-Belt-like) dust populations. The measured levels for such stars are clustering close to the KIN detection limit of a few hundred zodis and are indeed consistent with those expected from a populat [less ▲]Detailed reference viewed: 24 (8 ULiège) Fundamental Limitations of High Contrast Imaging Set by Small Sample StatisticsMawet, D.; Milli, J.; Wahhaj, Z. et alin Astrophysical Journal (2014), 792In this paper, we review the impact of small sample statistics on detection thresholds and corresponding confidence levels (CLs) in high-contrast imaging at small angles. When looking close to the star ... [more ▼]In this paper, we review the impact of small sample statistics on detection thresholds and corresponding confidence levels (CLs) in high-contrast imaging at small angles. When looking close to the star, the number of resolution elements decreases rapidly toward small angles. This reduction of the number of degrees of freedom dramatically affects CLs and false alarm probabilities. Naively using the same ideal hypothesis and methods as for larger separations, which are well understood and commonly assume Gaussian noise, can yield up to one order of magnitude error in contrast estimations at fixed CL. The statistical penalty exponentially increases toward very small inner working angles. Even at 5-10 resolution elements from the star, false alarm probabilities can be significantly higher than expected. Here we present a rigorous statistical analysis that ensures robustness of the CL, but also imposes a substantial limitation on corresponding achievable detection limits (thus contrast) at small angles. This unavoidable fundamental statistical effect has a significant impact on current coronagraphic and future high-contrast imagers. Finally, the paper concludes with practical recommendations to account for small number statistics when computing the sensitivity to companions at small angles and when exploiting the results of direct imaging planet surveys. [less ▲]Detailed reference viewed: 36 (9 ULiège) L'-band AGPM vector vortex coronagraph's first light on LBTI/LMIRCamDefrere, Denis ; Absil, Olivier ; Hinz, P. et alin Proceedings of SPIE - The International Society for Optical Engineering (2014, July 21)We present the first observations obtained with the L'-band AGPM vortex coronagraph recently installed on LBTI/LMIRCam. The AGPM (Annular Groove Phase Mask) is a vector vortex coronagraph made from ... [more ▼]We present the first observations obtained with the L'-band AGPM vortex coronagraph recently installed on LBTI/LMIRCam. The AGPM (Annular Groove Phase Mask) is a vector vortex coronagraph made from diamond subwavelength gratings. It is designed to improve the sensitivity and dynamic range of high-resolution imaging at very small inner working angles, down to 0.09 arcseconds in the case of LBTI/LMIRCam in the L' band. During the first hours on sky, we observed the young A5V star HR8799 with the goal to demonstrate the AGPM performance and assess its relevance for the ongoing LBTI planet survey (LEECH). Preliminary analyses of the data reveal the four known planets clearly at high SNR and provide unprecedented sensitivity limits in the inner planetary system (down to the diffraction limit of 0.09 arcseconds). © 2014 SPIE. [less ▲]Detailed reference viewed: 28 (8 ULiège) Co-phasing the Large Binocular Telescope: status and performance of LBTI/PHASECamDefrere, Denis ; Hinz, P.; Downey, E. et alin Optical and Infrared Interferometry IV (2014, July 01)The Large Binocular Telescope Interferometer is a NASA-funded nulling and imaging instrument designed to coherently combine the two 8.4-m primary mirrors of the LBT for high-sensitivity, high-contrast ... [more ▼]The Large Binocular Telescope Interferometer is a NASA-funded nulling and imaging instrument designed to coherently combine the two 8.4-m primary mirrors of the LBT for high-sensitivity, high-contrast, and highresolution infrared imaging (1.5-13 μm). PHASECam is LBTI's near-infrared camera used to measure tip-tilt and phase variations between the two AO-corrected apertures and provide high-angular resolution observations. We report on the status of the system and describe its on-sky performance measured during the first semester of 2014. With a spatial resolution equivalent to that of a 22.8-meter telescope and the light-gathering power of single 11.8-meter mirror, the co-phased LBT can be considered to be a forerunner of the next-generation extremely large telescopes (ELT). [less ▲]Detailed reference viewed: 33 (11 ULiège) The LBTI hunt for observable signatures of terrestrial systems (HOSTS) survey: a key NASA science program on the road to exoplanet imaging missionsDanchi, W.; Bailey, V.; Bryden, G. et alin Optical and Infrared Interferometry IV (2014, July 01)The Hunt for Observable Signatures of Terrestrial planetary Systems (HOSTS) program on the Large Binocular Telescope Interferometer (LBTI) will survey nearby stars for faint exozodiacal dust (exozodi ... [more ▼]The Hunt for Observable Signatures of Terrestrial planetary Systems (HOSTS) program on the Large Binocular Telescope Interferometer (LBTI) will survey nearby stars for faint exozodiacal dust (exozodi). This warm circumstellar dust, analogous to the interplanetary dust found in the vicinity of the Earth in our own system, is produced in comet breakups and asteroid collisions. Emission and/or scattered light from the exozodi will be the major source of astrophysical noise for a future space telescope aimed at direct imaging and spectroscopy of terrestrial planets (exo- Earths) around nearby stars. About 20% of nearby field stars have cold dust coming from planetesimals at large distances from the stars (Eiroa et al. 2013, A&A, 555, A11; Siercho et al. 2014, ApJ, 785, 33). Much less is known about exozodi; current detection limits for individual stars are at best ~ 500 times our solar system's level (aka. 500 zodi). LBTI-HOSTS will be the first survey capable of measuring exozodi at the 10 zodi level (3σ). Detections of warm dust will also reveal new information about planetary system architectures and evolution. We will describe the motivation for the survey and progress on target selection, not only the actual stars likely to be observed by such a mission but also those whose observation will enable sensible extrapolations for stars that will not be observed with LBTI. We briefly describe the detection of the debris disk around η Crv, which is the first scientific result from the LBTI coming from the commissioning of the instrument in December 2013, shortly after the first time the fringes were stabilized. [less ▲]Detailed reference viewed: 15 (1 ULiège) The Hunt for Observable Signatures of Terrestrial Planetary Systems (HOSTS)Defrere, Denis ; Hinz, P.; Bryden, G. et alConference (2014, March)The presence of large amounts of exozodiacal dust around nearby main sequence stars is considered as a potential threat for the direct imaging of Earth-like exoplanets and, hence, the search for ... [more ▼]The presence of large amounts of exozodiacal dust around nearby main sequence stars is considered as a potential threat for the direct imaging of Earth-like exoplanets and, hence, the search for biosignatures (Roberge et al. 2012). However, it is also considered as a signpost for the presence of terrestrial planets that might be hidden in the dust disk (Stark and Kuchner 2008). Characterizing exozodiacal dust around nearby sequence stars is therefore a crucial step toward one of the main goals of modern astronomy: finding extraterrestrial life. After briefly reviewing the latest results in this field, we present the exozodiacal dust survey on the Large Binocular Telescope Interferometer (LBTI). The survey is called HOSTS and is specifically designed to determine the prevalence and brightness of exozodiacal dust disks with the sensitivity required to prepare for future New Worlds Missions that will image Earth-like exoplanets. To achieve this objective, the LBTI science team has carefully established a balanced list of 50 nearby main-sequence stars that are likely candidates of these missions and/or can be observed with the best instrument performance (see companion abstract by Roberge et al.). Exozodiacal dust disk candidates detected by the Keck Interferometer Nuller will also be observed. The first results of the survey will be presented. To precisely detect exozodiacal dust, the LBTI combines the two 8-m primary mirrors of the LBT using N-band nulling interferometry. Interferometric combination provides the required angular resolution (70-90 mas) to resolve the habitable zone of nearby main sequence stars while nulling is used to subtract the stellar light and reach the required contrast of a few 10-4. A Kband fringe tracker ensures the stability of the null. The current performance of the instrument and the first nulling measurements will be presented. [less ▲]Detailed reference viewed: 16 (4 ULiège) L'-band AGPM vector vortex coronagraph's first light on LBTI/LMIRCAMDefrere, Denis ; Absil, Olivier ; Hinz, P. et alPoster (2014, March)We present the first science observations obtained with the L'-band AGPM coronagraph recently installed on LBTI/LMIRCAM. The AGPM (Annular Groove Phase Mask) is a vector vortex coronagraph made from ... [more ▼]We present the first science observations obtained with the L'-band AGPM coronagraph recently installed on LBTI/LMIRCAM. The AGPM (Annular Groove Phase Mask) is a vector vortex coronagraph made from diamond sub-wavelength gratings tuned to the L'-band. It is designed to improve the sensitivity and dynamic range of high-resolution imaging at very small inner working a [less ▲]Detailed reference viewed: 48 (10 ULiège) Exozodi disk models for the HOSTS survey on the LBTIWyatt, Mark; Kennedy, G.; Skemer, A. et alin American Astronomical Society Meeting Abstracts #223 (2014, January 01)This poster describes a simple model for exozodiacal emission that was developed to interpret observations of the Hunt for Observable Signatures of Terrestrial planetary Systems (HOSTS) project on the ... [more ▼]This poster describes a simple model for exozodiacal emission that was developed to interpret observations of the Hunt for Observable Signatures of Terrestrial planetary Systems (HOSTS) project on the Large Binocular Telescope Interferometer (LBTI). HOSTS is a NASA-funded key science project using mid-infrared nulling interferometry at the LBTI to seach for faint exozodiacal dust (exozodi) in the habitable zones of nearby stars. The aim was to make a model that includes the fewest possible assumptions, so that it is easy to characterize how choices of model parameters affect what can be inferred from the observations. However the model is also sufficiently complex that it can be compared in a physically meaningful way with the level of dust in the Solar System, and can also be readily used to assess the impact of a detection (or of a non-detection) on the ability of a mission to detect Earth-like planets. Here we describe the model, and apply it to the sample of stars being searched by HOSTS to determine the zodi level (i.e., the number of Solar System zodiacal clouds) that would be needed for a detection for each star in the survey. Particular emphasis is given to our definition of a zodi, and what that means for stars of different luminosity, and a comparison is given between different zodi definitions justifying our final choice. The achievable exozodi levels range from 1-20 zodi for different stars in the prime sample for a 0.01% null depth, with a median level of 2.5 zodi. [less ▲]Detailed reference viewed: 11 (3 ULiège) Target Selection for the LBTI Hunt for Observable Signatures of Terrestrial Planetary SystemsWeinberger, Alycia J.; Roberge, A.; Kennedy, G. et alin American Astronomical Society Meeting Abstracts #223 (2014, January 01)The Hunt for Observable Signatures of Terrestrial planetary Systems (HOSTS) on the Large Binocular Telescope Interferometer (LBTI) will survey nearby stars for faint exozodiacal dust (exozodi). About 20 ... [more ▼]The Hunt for Observable Signatures of Terrestrial planetary Systems (HOSTS) on the Large Binocular Telescope Interferometer (LBTI) will survey nearby stars for faint exozodiacal dust (exozodi). About 20% of field stars have cold debris disks created by the collisions and evaporation of planetesimals. Much less is known about warm circumstellar dust, such as that found in the vicinity of the Earth in our own system. This dust is generated in asteroidal collisions and cometary breakups, and current detection limits are at best ~500 times our system's level, i.e. 500 zodi. LBTI-HOSTS will be the first survey capable of measuring exozodi at the 10 zodi level (3σ). Exozodi of this brightness would be the major source of astrophysical noise for a future space telescope aimed at direct imaging and spectroscopy of habitable zone terrestrial planets. Detections of warm dust will also reveal new information about planetary system architectures and evolution. We describe the target star selection by the LBTI Science Team to satisfy the goals of the HOSTS survey -- to fully inform target selection for a future exoEarth mission. We are interested in actual stars likely to be observed by a mission and stars whose observation will enable sensible extrapolations to those stars that cannot be observed. We integrated two approaches to generate the HOSTS target list. The mission-driven approach concentrates on F, G, and K-type stars that are the best targets for future direct observations of exoEarths, thereby providing model-independent “ground truth” dust observations. However, not every potential target of a future exoEarth mission can be observed with LBTI. The sensitivity-driven approach selects targets based only on what exozodi sensitivity could be achieved, without consideration of exoEarth mission constraints. This naturally selects more luminous stars (A and early F-type stars). In both cases, all stars are close enough to Earth such that their habitable zones are resolvable by LBTI and bright enough at N-band (10 μm) to provide excellent sensitivity. We also discuss observational and astrophysical motivations for excluding binaries of certain separations. [less ▲]Detailed reference viewed: 5 (1 ULiège) 1 2