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See detailThe STAR contribution to ELT/METIS
Absil, Olivier ULiege

Scientific conference (2019, February 04)

I will focus on how STAR is currently contributing to the METIS project, the perspectives for becoming a formal partner in the METIS collaboration, and how this could benefit all STAR astronomers.

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See detailDeep Exploration of ɛ Eridani with Keck Ms-band Vortex Coronagraphy and Radial Velocities: Mass and Orbital Parameters of the Giant Exoplanet
Mawet, Dimitri; Hirsch, Lea; Lee, Eve J. et al

in Astronomical Journal (2019), 157

We present the most sensitive direct imaging and radial velocity (RV) exploration of ɛ Eridani to date. ɛ Eridani is an adolescent planetary system, reminiscent of the early solar system. It is surrounded ... [more ▼]

We present the most sensitive direct imaging and radial velocity (RV) exploration of ɛ Eridani to date. ɛ Eridani is an adolescent planetary system, reminiscent of the early solar system. It is surrounded by a prominent and complex debris disk that is likely stirred by one or several gas giant exoplanets. The discovery of the RV signature of a giant exoplanet was announced 15 yr ago, but has met with scrutiny due to possible confusion with stellar noise. We confirm the planet with a new compilation and analysis of precise RV data spanning 30 yr, and combine it with upper limits from our direct imaging search, the most sensitive ever performed. The deep images were taken in the Ms band (4.7 μm) with the vortex coronagraph recently installed in W.M. Keck Observatory’s infrared camera NIRC2, which opens a sensitive window for planet searches around nearby adolescent systems. The RV data and direct imaging upper limit maps were combined in an innovative joint Bayesian analysis, providing new constraints on the mass and orbital parameters of the elusive planet. ɛ Eridani b has a mass of {0.78}[SUB]-0.12[/SUB][SUP]+0.38[/SUP] M [SUB]Jup[/SUB] and is orbiting ɛ Eridani at about 3.48 ± 0.02 au with a period of 7.37 ± 0.07 yr. The eccentricity of ɛ Eridani b’s orbit is {0.07}[SUB]-0.05[/SUB][SUP]+0.06[/SUP], an order of magnitude smaller than early estimates and consistent with a circular orbit. We discuss our findings from the standpoint of planet–disk interactions and prospects for future detection and characterization with the James Webb Space Telescope. Based on observations obtained at the W. M. Keck Observatory, which is operated jointly by the University of California and the California Institute of Technology. Keck time was granted for this project by Caltech, the University of Hawai’i, the University of California, and NASA. [less ▲]

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See detailSpace-based infrared interferometry to study exoplanetary atmospheres
Defrere, Denis ULiege; Léger, A.; Absil, Olivier ULiege et al

in Experimental Astronomy (2018), 46(3), 543-560

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 ... [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 ▲]

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See detailSingle conjugate adaptive optics for the ELT instrument METIS
Hippler, Stefan; Feldt, Markus; Bertram, Thomas et al

in Experimental Astronomy (2018)

The European Extremely Large Telescope (ELT) is a 39m large, ground-based optical and near- to mid-infrared telescope under construction in the Chilean Atacama desert. Operation is planned to start around ... [more ▼]

The European Extremely Large Telescope (ELT) is a 39m large, ground-based optical and near- to mid-infrared telescope under construction in the Chilean Atacama desert. Operation is planned to start around the middle of the next decade. All first light instruments will come with wavefront sensing devices that allow control of the ELT's intrinsic M4 and M5 wavefront correction units, thus building an adaptive optics (AO) system. To take advantage of the ELT's optical performance, full diffraction-limited operation is required and only a high performance AO system can deliver this. Further technically challenging requirements for the AO come from the exoplanet research field, where the task to resolve the very small angular separations between host star and planet, has also to take into account the high-contrast ratio between the two objects. We present in detail the results of our simulations and their impact on high-contrast imaging in order to find the optimal wavefront sensing device for the METIS instrument. METIS is the mid-infrared imager and spectrograph for the ELT with specialised high-contrast, coronagraphic imaging capabilities, whose performance strongly depends on the AO residual wavefront errors. We examined the sky and target sample coverage of a generic wavefront sensor in two spectral regimes, visible and near-infrared, to pre-select the spectral range for the more detailed wavefront sensor type analysis. We find that the near-infrared regime is the most suitable for METIS. We then analysed the performance of Shack-Hartmann and pyramid wavefront sensors under realistic conditions at the ELT, did a balancing with our scientific requirements, and concluded that a pyramid wavefront sensor is the best choice for METIS. For this choice we additionally examined the impact of non-common path aberrations, of vibrations, and the long-term stability of the SCAO system including high-contrast imaging performance. [less ▲]

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See detailCharacterization of low-mass companion HD 142527 B
Christiaens, Valentin ULiege; Casassus, Simon; Absil, Olivier ULiege et al

in Astronomy and Astrophysics (2018), 617

The circumstellar disk of the Herbig Fe star HD 142527 is host to several remarkable features including a warped inner disk, a 120 au-wide annular gap, a prominent dust trap and several spiral arms. A low ... [more ▼]

The circumstellar disk of the Herbig Fe star HD 142527 is host to several remarkable features including a warped inner disk, a 120 au-wide annular gap, a prominent dust trap and several spiral arms. A low-mass companion, HD 142527 B, was also found orbiting the primary star at ~14 au. This study aims to better characterize this companion, which could help explain its impact on the peculiar geometry of the disk. We observed the source with VLT/SINFONI in H+K band in pupil-tracking mode. Data were post-processed with several algorithms based on angular differential imaging (ADI). HD 142527 B is conspicuously re-detected in most spectral channels, which enables us to extract the first medium-resolution spectrum of a low-mass companion within 0.1'' from its central star. Fitting our spectrum with both template and synthetic spectra suggests that the companion is a young M2.5+-1.0 star with an effective temperature of 3500+-100 K, possibly surrounded with a hot (1700 K) circum-secondary environment. Pre-main sequence evolutionary tracks provide a mass estimate of 0.34+-0.06 MSun, independent of the presence of a hot environment. However, the estimated stellar radius and age do depend on that assumption; we find a radius of 1.37+-0.05 RSun (resp. 1.96+-0.10 RSun) and an age of ~1.8Myr (resp. ~0.75Myr) in the case of the presence (resp. absence) of a hot environment contributing in H+K. Our new values for the mass and radius of the companion yield a mass accretion rate of 2--3% that of the primary. We have constrained the physical properties of HD 142527 B, thereby illustrating the potential for SINFONI+ADI to characterize faint close-in companions. The new spectral type makes HD 142527 B a twin of the well known TW Hya T-Tauri star, and the revision of its mass to higher values further supports its role in shaping the disk. [less ▲]

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See detailCharacterizing the Performance of the NIRC2 Vortex Coronagraph at W. M. Keck Observatory
Xuan, W. Jerry; Mawet, Dimitri; Ngo, Henry et al

in Astronomical Journal (2018), 156

The NIRC2 vortex coronagraph is an instrument on Keck II designed to directly image exoplanets and circumstellar disks at mid-infrared bands L‧ (3.4–4.1 μm) and M [SUB] s [/SUB] (4.55–4.8 μm). We analyze ... [more ▼]

The NIRC2 vortex coronagraph is an instrument on Keck II designed to directly image exoplanets and circumstellar disks at mid-infrared bands L‧ (3.4–4.1 μm) and M [SUB] s [/SUB] (4.55–4.8 μm). We analyze imaging data and corresponding adaptive optics telemetry, observing conditions, and other metadata over a three-year time period to characterize the performance of the instrument and predict the detection limits of future observations. We systematically process images from 359 observations of 304 unique stars to subtract residual starlight (i.e., the coronagraphic point-spread function) of the target star using two methods: angular differential imaging (ADI) and reference star differential imaging (RDI). We find that for the typical parallactic angle (PA) rotation of our data set (∼10°), RDI provides gains over ADI for angular separations smaller than 0.″25. Furthermore, we find a power-law relation between the angular separation from the host star and the minimum PA rotation required for ADI to outperform RDI, with a power-law index of ‑1.18 ± 0.08. Finally, we use random forest models to estimate ADI and RDI post-processed detection limits a priori. These models, which we provide publicly on a website, explain 70%–80% of the variance in ADI detection limits and 30%–50% of the variance in RDI detection limits. Averaged over a range of angular separations, our models predict both ADI and RDI contrast to within a factor of 2. These results illuminate important factors in high-contrast imaging observations with the NIRC2 vortex coronagraph, help improve observing strategies, and inform future upgrades to the hardware. [less ▲]

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See detailReview of high-contrast imaging systems for current and future ground- and space-based telescopes I: coronagraph design methods and optical performance metrics
Ruane, G.; Riggs, A.; Mazoyer, J. et al

in Lystrup, M.; MacEwen, H.; Fazio, G. (Eds.) et al Space Telescopes and Instrumentation 2018: Optical, Infrared, and Millimeter Wave (2018, August 21)

The Optimal Optical Coronagraph (OOC) Workshop at the Lorentz Center in September 2017 in Leiden, the Netherlands gathered a diverse group of 25 researchers working on exoplanet instrumentation to ... [more ▼]

The Optimal Optical Coronagraph (OOC) Workshop at the Lorentz Center in September 2017 in Leiden, the Netherlands gathered a diverse group of 25 researchers working on exoplanet instrumentation to stimulate the emergence and sharing of new ideas. In this first installment of a series of three papers summarizing the outcomes of the OOC workshop, we present an overview of design methods and optical performance metrics developed for coronagraph instruments. The design and optimization of coronagraphs for future telescopes has progressed rapidly over the past several years in the context of space mission studies for Exo-C, WFIRST, HabEx, and LUVOIR as well as ground-based telescopes. Design tools have been developed at several institutions to optimize a variety of coronagraph mask types. We aim to give a broad overview of the approaches used, examples of their utility, and provide the optimization tools to the community. Though it is clear that the basic function of coronagraphs is to suppress starlight while maintaining light from off-axis sources, our community lacks a general set of standard performance metrics that apply to both detecting and characterizing exoplanets. The attendees of the OOC workshop agreed that it would benefit our community to clearly define quantities for comparing the performance of coronagraph designs and systems. Therefore, we also present a set of metrics that may be applied to theoretical designs, testbeds, and deployed instruments. We show how these quantities may be used to easily relate the basic properties of the optical instrument to the detection significance of the given point source in the presence of realistic noise. [less ▲]

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See detailProspects for the characterisation of exo-zodiacal dust with the VLTI
Ertel, S.; Absil, Olivier ULiege; Defrere, Denis ULiege et al

in Experimental Astronomy (2018), 46(3), 401411

Exo-zodiacal dust, exozodi for short, is warm (∼300 K) or hot (up to ∼2000 K) dust found in the inner regions of planetary systems around main sequence stars. In analogy to our own zodiacal dust, it may ... [more ▼]

Exo-zodiacal dust, exozodi for short, is warm (∼300 K) or hot (up to ∼2000 K) dust found in the inner regions of planetary systems around main sequence stars. In analogy to our own zodiacal dust, it may be located in or near the habitable zone or closer in, down to the dust sublimation distance. The study of the properties, distribution, and evolution of exozodis can inform about the architecture and dynamics of the innermost regions of planetary systems, close to their habitable zones. On the other hand, the presence of large amounts of exo-zodiacal dust may be an obstacle for future space missions aiming to image Earth-like exoplanets. The dust can be the most luminous component of extrasolar planetary systems, but predominantly emits in the near- to mid-infrared where it is outshone by the host star. Interferometry provides a unique method of separating the dusty from the stellar emission. We discuss the prospects of exozodi observations with the next generation VLTI instruments and summarize critical instrument specifications. © 2018, Springer Nature B.V. [less ▲]

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See detailHigh contrast imaging for the enhanced resolution imager and spectrometer (ERIS)
Kenworthy, M. A.; Snik, F.; Keller, C. U. et al

in Evans, C.; Simard, L.; Takami, H. (Eds.) Ground-based and Airborne Instrumentation for Astronomy VII (2018, July 27)

ERIS is a diffraction limited thermal infrared imager and spectrograph for the Very Large Telescope UT4. One of the science cases for ERIS is the detection and characterization of circumstellar structures ... [more ▼]

ERIS is a diffraction limited thermal infrared imager and spectrograph for the Very Large Telescope UT4. One of the science cases for ERIS is the detection and characterization of circumstellar structures and exoplanets around bright stars that are typically much fainter than the stellar diffraction halo. Enhanced sensitivity is provided through the combination of (i) suppression of the diffraction halo of the target star using coronagraphs, and (ii) removal of any residual diffraction structure through focal plane wavefront sensing and subsequent active correction. In this paper we present the two coronagraphs used for diffraction suppression and enabling high contrast imaging in ERIS. © 2018 SPIE. [less ▲]

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See detailA review of high contrast imaging modes for METIS
Kenworthy, M. A.; Absil, Olivier ULiege; Carlomagno, Brunella ULiege et al

in Evans, C.; Simard, L.; Takami, H. (Eds.) Ground-based and Airborne Instrumentation for Astronomy VII (2018, July 16)

The Mid-infrared E-ELT Imager and Spectrograph (METIS) for the European Extremely Large Telescope (E- ELT) consists of diffraction-limited imagers that cover 3 to 14 microns with medium resolution (R ∼ ... [more ▼]

The Mid-infrared E-ELT Imager and Spectrograph (METIS) for the European Extremely Large Telescope (E- ELT) consists of diffraction-limited imagers that cover 3 to 14 microns with medium resolution (R ∼ 5000) long slit spectroscopy, and an integral field spectrograph for high spectral resolution spectroscopy (R ∼ 100,000) over the L and M bands. We present our approach for high contrast imaging with METIS, covering diffraction suppression with coronagraphs, the removal of residual aberrations using QACITS1, 2 and Phase Sorting Interferometry (PSI),3 and simulations demonstrating the expected contrast. [less ▲]

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See detailStatus of the mid-IR ELT imager and spectrograph (METIS)
Brandl, B. R.; Absil, Olivier ULiege; Agócs, T. et al

in Evans, C.; Simard, L.; Takami, H. (Eds.) Ground-based and Airborne Instrumentation for Astronomy VII (2018, July 12)

The Mid-Infrared ELT Imager and Spectrograph (METIS) is one of three first light instruments on the ELT. It will provide high-contrast imaging and medium resolution, slit-spectroscopy from 3 - 19um, as ... [more ▼]

The Mid-Infrared ELT Imager and Spectrograph (METIS) is one of three first light instruments on the ELT. It will provide high-contrast imaging and medium resolution, slit-spectroscopy from 3 - 19um, as well as high resolution (R ∼ 100,000) integral field spectroscopy from 2.9-5.3μm. All modes observe at the diffraction limit of the ELT, by means of adaptive optics, yielding angular resolutions of a few tens of milliarcseconds. The range of METIS science is broad, from Solar System objects to active galactic nuclei (AGN). We will present an update on the main science drivers for METIS: circum-stellar disks and exoplanets. The METIS project is now in full steam, approaching its preliminary design review (PDR) in 2018. In this paper we will present the current status of its optical, mechanical and thermal design as well as operational aspects. We will also discuss the challenges of building an instrument for the ELT, and the required technologies. © 2018 SPIE. [less ▲]

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See detailPreliminary design of SALTO, the Belgian adaptive optics demonstrator
Orban De Xivry, Gilles ULiege; Absil, Olivier ULiege; Lismont, Marjorie et al

in Close, Laird; Schreiber, Laura; Schmidt, Dirk (Eds.) Adaptive Optics System VI (2018, July 11)

SALTO is a Belgian project aiming to build a complete 1 m telescope demonstrator including a single-conjugated adaptive optics (AO) system together with a Rayleigh laser guide star system. The underlying ... [more ▼]

SALTO is a Belgian project aiming to build a complete 1 m telescope demonstrator including a single-conjugated adaptive optics (AO) system together with a Rayleigh laser guide star system. The underlying objective of SALTO consists in developing the Belgian expertise regarding AO systems for medium size telescopes (i.e. diameter from 1 to 4m), for application in astronomy, optical communication or detection of low-Earth orbit objects. The project approach is to base the design on COTS components, in order to reduce complexity, and to favor both robustness and automation of the system over performance. The SALTO demonstrator will be located at Redu Space Services in the Belgian countryside. Therefore the major challenge of the project will be to deal with poor seeing, far worst than astronomical standards, while preserving robust and reasonable correction in the red-visible and near-infrared wavelength range. Here, we present our system baseline, the expected performance, and the preliminary design of the AO system. We conclude with the current prospects for the project. [less ▲]

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See detailSingle conjugate adaptive optics for METIS
Bertram, Thomas; Absil, Olivier ULiege; Bizenberger, Peter et al

in Close, L.; Schreiber, L.; Schmidt, D. (Eds.) Adaptive Optics Systems VI (2018, July 10)

METIS is the Mid-infrared Extremely large Telescope Imager and Spectrograph, one of the first generation instruments of ESO's 39m ELT. All scientific observing modes of METIS require adaptive optics (AO ... [more ▼]

METIS is the Mid-infrared Extremely large Telescope Imager and Spectrograph, one of the first generation instruments of ESO's 39m ELT. All scientific observing modes of METIS require adaptive optics (AO) correction close to the diffraction limit. Demanding constraints are introduced by the foreseen coronagraphy modes, which require highest angular resolution and PSF stability. Further design drivers for METIS and its AO system are imposed by the wavelength regime: observations in the thermal infrared require an elaborate thermal, baffling and masking concept. METIS will be equipped with a Single-Conjugate Adaptive Optics (SCAO) system. An integral part of the instrument is the SCAO module. It will host a pyramid type wavefront sensor, operating in the near-IR and located inside the cryogenic environment of the METIS instrument. The wavefront control loop as well as secondary control tasks will be realized within the AO Control System, as part of the instrument. Its main actuators will be the adaptive quaternary mirror and the field stabilization mirror of the ELT. In this paper we report on the phase B design work for the METIS SCAO system; the opto-mechanical design of the SCAO module as well as the control loop concepts and analyses. Simulations were carried out to address a number of important aspects, such as the impact of the fragmented pupil of the ELT on wavefront reconstruction. The trade-off that led to the decision for a pyramid wavefront sensor will be explained, as well as the additional control tasks such as pupil stabilization and compensation of non-common path aberrations. [less ▲]

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See detailReview of high-contrast imaging systems for current and future ground-based and space-based telescopes: Part II. Common path wavefront sensing/control and coherent differential imaging
Jovanovic, Nemanja; Absil, Olivier ULiege; Baudoz, Pierre et al

in Close, L.; Schreiber, L.; Schmidt, D. (Eds.) Adaptive Optics Systems VI (2018, July 10)

The Optimal Optical Coronagraph (OOC) Workshop held at the Lorentz Center in September 2017 in Leiden, the Netherlands, gathered a diverse group of 25 researchers working on exoplanet instrumentation to ... [more ▼]

The Optimal Optical Coronagraph (OOC) Workshop held at the Lorentz Center in September 2017 in Leiden, the Netherlands, gathered a diverse group of 25 researchers working on exoplanet instrumentation to stimulate the emergence and sharing of new ideas. In this second installment of a series of three papers summarizing the outcomes of the OOC workshop, we present an overview of common path wavefront sensing/control and Coherent Differential Imaging techniques, highlight the latest results, and expose their relative strengths and weaknesses. We layout critical milestones for the field with the aim of enhancing future ground/space based high contrast imaging platforms. Techniques like these will help to bridge the daunting contrast gap required to image a terrestrial planet in the zone where it can retain liquid water, in reflected light around a G type star from space. [less ▲]

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See detailReview of high-contrast imaging systems for current and future ground-based and space-based telescopes III: technology opportunities and pathways
Snik, Frans; Absil, Olivier ULiege; Baudoz, Pierre et al

in Navarro, R.; Geyl, R. (Eds.) Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation III (2018, July 10)

The Optimal Optical CoronagraphWorkshop at the Lorentz Center in September 2017 in Leiden, the Netherlands gathered a diverse group of 30 researchers working on exoplanet instrumentation to stimulate the ... [more ▼]

The Optimal Optical CoronagraphWorkshop at the Lorentz Center in September 2017 in Leiden, the Netherlands gathered a diverse group of 30 researchers working on exoplanet instrumentation to stimulate the emergence and sharing of new ideas. This contribution is the final part of a series of three papers summarizing the outcomes of the workshop, and presents an overview of novel optical technologies and systems that are implemented or considered for high-contrast imaging instruments on both ground-based and space telescopes. The overall objective of high contrast instruments is to provide direct observations and characterizations of exoplanets at contrast levels as extreme as 10[SUP]-10[/SUP]. We list shortcomings of current technologies, and identify opportunities and development paths for new technologies that enable quantum leaps in performance. Specifically, we discuss the design and manufacturing of key components like advanced deformable mirrors and coronagraphic optics, and their amalgamation in "adaptive coronagraph" systems. Moreover, we discuss highly integrated system designs that combine contrast-enhancing techniques and characterization techniques (like high-resolution spectroscopy) while minimizing the overall complexity. Finally, we explore extreme implementations using all-photonics solutions for ground-based telescopes and dedicated huge apertures for space telescopes. [less ▲]

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See detailExoplanet science with a space-based mid-infrared nulling interferometer
Quanz, S. P.; Kammerer, J.; Defrere, Denis ULiege et al

in Creech-Eakman, M.; Tuthill, P.; Mérand, A. (Eds.) Optical and Infrared Interferometry and Imaging VI (2018, July 09)

One of the long-term goals of exoplanet science is the (atmospheric) characterization of a large sample (>100) of terrestrial planets to assess their potential habitability and overall diversity. Hence ... [more ▼]

One of the long-term goals of exoplanet science is the (atmospheric) characterization of a large sample (>100) of terrestrial planets to assess their potential habitability and overall diversity. Hence, it is crucial to quantitatively evaluate and compare the scientific return of various mission concepts. Here we discuss the exoplanet yield of a space-based mid-infrared (MIR) nulling interferometer. We use Monte-Carlo simulations, based on the observed planet population statistics from the Kepler mission, to quantify the number and properties of detectable exoplanets (incl. potentially habitable planets) and we compare the results to those for a large aperture optical/NIR space telescope. We investigate how changes in the underlying technical assumptions (sensitivity and spatial resolution) impact the results and discuss scientific aspects that influence the choice for the wavelength coverage and spectral resolution. Finally, we discuss the advantages of detecting exoplanets at MIR wavelengths, summarize the current status of some key technologies, and describe what is needed in terms of further technology development to pave the road for a space-based MIR nulling interferometer for exoplanet science. © 2018 SPIE. [less ▲]

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See detailHi-5: A potential high-contrast thermal near-infrared imager for the VLTI
Defrere, Denis ULiege; Ireland, M.; Absil, Olivier ULiege et al

in Proceedings of SPIE: The International Society for Optical Engineering (2018, July 09), 10701

Hi-5 is a high-contrast (or high dynamic range) infrared imager project for the VLTI. Its main goal is to characterize young extra-solar planetary systems and exozodiacal dust around southern main ... [more ▼]

Hi-5 is a high-contrast (or high dynamic range) infrared imager project for the VLTI. Its main goal is to characterize young extra-solar planetary systems and exozodiacal dust around southern main-sequence stars. In this paper, we present an update of the project and key technology pathways to improve the contrast achieved by the VLTI. 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 μm) and advanced fringe tracking strategies. We also address the strong exoplanet science case (young exoplanets, planet formation, and exozodiacal disks) offered by this wavelength regime as well as other possible science cases such as 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. © 2018 SPIE. [less ▲]

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See detailCharacterizing the atmosphere of Proxima b with a space-based mid-infrared nulling interferometer
Defrere, Denis ULiege; Léger, A.; Absil, Olivier ULiege et al

in Proceedings of SPIE: The International Society for Optical Engineering (2018, July 09), 10701

Proxima b is our nearest potentially rocky exoplanet and represents a formidable opportunity for exoplanet science and possibly astrobiology. With an angular separation of only 35 mas (or 0.05 AU) from ... [more ▼]

Proxima b is our nearest potentially rocky exoplanet and represents a formidable opportunity for exoplanet science and possibly astrobiology. With an angular separation of only 35 mas (or 0.05 AU) from its host star, Proxima b is however hardly observable with current imaging telescopes and future space-based coronagraphs. One way to separate the photons of the planet from those of its host star is to use an interferometer that can easily resolve such spatial scales. In addition, its proximity to Earth and its favorable contrast ratio compared with its host M dwarf (approximately 10-5 at 10 microns) makes it an ideal target for a space-based nulling interferometer with relatively small apertures. In this paper, we present the motivation for observing this planet in the mid-infrared (5-20 microns) and the corresponding technological challenges. Then, we describe the concept of a space-based infrared interferometer with relatively small (<1m in diameter) apertures that can measure key details of Proxima b, such as its size, temperature, climate structure, as well as the presence of important atmospheric molecules such as H2O, CO2, O3, and CH4. Finally, we illustrate the concept by showing realistic observations using synthetic spectra of Proxima b computed with coupled climate chemistry models. © 2018 SPIE. [less ▲]

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See detailNEAR: New earths in the Alpha Cen Region (bringing VISIR as a "visiting instrument" to ESO-VLT-UT4)
Käufl, H.-U.; Kasper, M.; Arsenault, R. et al

in Evans, C.; Simard, L.; Takami (Eds.) Ground-based and Airborne Instrumentation for Astronomy VII (2018, July 06)

By adding a dedicated coronagraph, ESO in collaboration with the Breakthrough Initiatives, modifies the Very Large Telescope mid-IR imager (VISIR) to further boost the high dynamic range imaging ... [more ▼]

By adding a dedicated coronagraph, ESO in collaboration with the Breakthrough Initiatives, modifies the Very Large Telescope mid-IR imager (VISIR) to further boost the high dynamic range imaging capability this instru- ment has. After the VISIR upgrade in 2012, where coronagraphic masks were first added to VISIR, it became evident that coronagraphy at a ground-based 8m-class telescope critically needs adaptive optics, even at wavelengths as long as 10μm. For VISIR, a work-horse observatory facility instrument in normal operations, this is "easiest" achieved by bringing VISIR as a visiting instrument to the ESO-VLT-UT4 having an adaptive M2. This "visit" enables a meaningful search for Earth-like planets in the habitable zone around both α-Cen1,2. Meaningful here means, achieving a contrast of ∼ 10-6 within ∼ 0.8arcsec from the star while maintaining basically the normal sensitivity of VISIR. This should allow to detect a planet twice the diameter of Earth. Key components will be a diffractive coronagraphic mask, the annular groove phase mask (AGPM), optimized for the most sensitive spectral band-pass in the N-band, complemented by a sophisticated apodizer at the level of the Lyot stop. For VISIR noise filtering based on fast chopping is required. A novel internal chopper system will be integrated into the cryostat. This chopper is based on the standard technique from early radio astronomy, conceived by the microwave pioneer Robert Dicke in 1946, which was instrumental for the discovery of the 3K radio background. © 2018 SPIE. [less ▲]

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See detailDesign of the ERIS instrument control software
Baruffolo, A.; Salasnich, B.; Puglisi, A. et al

in Guzman, J.; Ibsen, J. (Eds.) Software and Cyberinfrastructure for Astronomy V (2018, July 06)

The Enhanced Resolution Imager and Spectrograph (ERIS) is a next-generation, adaptive optics assisted, near-IR imager and integral field spectrograph (IFS) for the Cassegrain focus of the Very Large ... [more ▼]

The Enhanced Resolution Imager and Spectrograph (ERIS) is a next-generation, adaptive optics assisted, near-IR imager and integral field spectrograph (IFS) for the Cassegrain focus of the Very Large Telescope (VLT) Unit Telescope 4. It will make use of the Adaptive Optics Facility (AOF), comprising the Deformable Secondary Mirror (DSM) and the UT4 Laser Guide Star Facility (4LGSF). It is a rather complex instrument, with its state of the art AO system and two science channels. It is also meant to be a «workhorse» instrument and offers many observation modes. ERIS is being built by a Consortium of European Institutes comprising MPE Garching (D), ATC (UK), ETH Zürich (CH), Leiden University (NL) and INAF (I) in collaboration with ESO. The instrument passed Final Design Review in mid-2017 and is now in the MAIT phase. In this paper we describe the design of the ERIS Instrument Software (INS), which is in charge of controlling all instrument functions and implementing observation, calibration and maintenance procedures. The complexity of the instrument is reflected in the architecture of its control software and the number of templates required for operations. After a brief overview of the Instrument, we describe the general architecture of the ERIS control network and software. We then discuss some of the most interesting aspects of ERIS INS, like the wavefront sensors function control, AO secondary loops, IFS quick-look processing and the on-line processing for high-contrast imaging observations. Finally, we provide some information about our development process, including software quality assurance activities. © 2018 SPIE. [less ▲]

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