High-contrast imaging with METIS

Kenworthy, Matthew A.; Absil, Olivier; Agócs, Tibor; Pantin, É.; Quanz, Sascha P.; Stuik, Remko; Snik, Frans; Brandl, Bernhard R.

doi:10.1117/12.2233655

Cited by 10 publications

(8 citation statements)

References 18 publications

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“…Future telescopes capable of direct imaging (Dalcanton et al 2015), such as the LUVOIR (Bolcar et al 2016) or HabEx (Mennesson et al 2016) mission concepts, as well as ground-based facilities, could potentially probe down to such short wavelengths. Alternatively, sulfur hazes may be discernible by thermal emission spectroscopy in the infrared, which has been conducted on young, bright giant exoplanets by groundbased observational campaigns (e.g., Kenworthy et al 2016;Macintosh et al 2016;Wagner et al 2016) and will be especially powerful in the era of theJames Webb Space Telescope (JWST). The refractive index of sulfur is essentially featureless between 1 and 2 μm, and a gap exists in the imaginary component between 2 and 7 μm, likely indicating that it was too low to be measured precisely.…”

Section: Discussionmentioning

confidence: 99%

Sulfur Hazes in Giant Exoplanet Atmospheres: Impacts on Reflected Light Spectra

Gao

Marley

Zahnle

et al. 2017

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Recent work has shown that sulfur hazes may arise in the atmospheres of some giant exoplanets, due to the photolysis of H 2 S. We investigate the impact such a haze would have on an exoplanet's geometric albedo spectrum and how it may affect the direct imaging results of the Wide Field Infrared Survey Telescope (WFIRST), a planned NASA space telescope. For temperate (250 K<T eq <700 K) Jupiter-mass planets, photochemical destruction of H 2 S results in the production of ∼1 ppmv of S 8 between 100 and 0.1 mbar, which, if cool enough, will condense to form a haze. Nominal haze masses are found to drastically alter a planet's geometric albedo spectrum: whereas a clear atmosphere is dark at wavelengths between 0.5 and 1 μm, due to molecular absorption, the addition of a sulfur haze boosts the albedo there to ∼0.7, due to scattering. Strong absorption by the haze shortward of 0.4 μm results in albedos <0.1, in contrast to the high albedos produced by Rayleigh scattering in a clear atmosphere. As a result, the color of the planet shifts from blue to orange. The existence of a sulfur haze masks the molecular signatures of methane and water, thereby complicating the characterization of atmospheric composition. Detection of such a haze by WFIRST is possible, though discriminating between a sulfur haze and any other highly reflective, high-altitude scatterer will require observations shortward of 0.4 μm, which is currently beyond WFIRST's design.

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Section: Discussionmentioning

confidence: 99%

Sulfur Hazes in Giant Exoplanet Atmospheres: Impacts on Reflected Light Spectra

Gao

Marley

Zahnle

et al. 2017

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“…Its baseline design features vortex phase masks and apodizing phase plates (APP 1 ) for imaging and spectroscopy at L, M and N atmospheric bands. 16 The E-ELT pupil contains 798 quasi-hexagonal segments, 1.45m from side to side, divided into 6 sectors (see Fig.2, left), with six 50cm-wide spider arms. It features a large central obstruction (around 11m in diameter, 30% of the outer diameter), which is not ideal for coronagraphic applications.…”

Section: The E-elt/metis Instrumentmentioning

confidence: 99%

End-to-end simulations of the E-ELT/METIS coronagraphs

et al. 2016

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The direct detection of low-mass planets in the habitable zone of nearby stars is an important science case for future E-ELT instruments such as the mid-infrared imager and spectrograph METIS, which features vortex phase masks and apodizing phase plates (APP) in its baseline design. In this work, we present end-to-end performance simulations, using Fourier propagation, of several METIS coronagraphic modes, including focal-plane vortex phase masks and pupil-plane apodizing phase plates, for the centrally obscured, segmented E-ELT pupil. The atmosphere and the AO contributions are taken into account. Hybrid coronagraphs combining the advantages of vortex phase masks and APPs are considered to improve the METIS coronagraphic performance.

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“…Two types of coronagraphic modes will be available in METIS, based either on a focal-plane vortex phase mask [57,58], or an apodizing pupil-plane phase mask [59]. Here, we illustrate the capability of the ring-apodized vortex coronagraph [60], one of the baseline observing modes of METIS [56,61], to reject light from the on-axis light during the observations of the 51 Eri exoplanetary system. be rejected by a factor ranging from 100 to 10000 in the inner 100 mas around the star, which leads to raw contrasts of the order of 10 −4 at a few resolution elements from the star.…”

Section: The Structure Of the Metis Coronagraphic Psfmentioning

confidence: 99%

Single conjugate adaptive optics for the ELT instrument METIS

et al. 2018

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The European Extremely Large Telescope (ELT) is a 39 m 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 noncommon path aberrations, of vibrations, and the long-term stability of the SCAO system including high-contrast imaging performance.Keywords Single conjugate adaptive optics · SCAO · ELT · Pyramid wavefront sensor · Shack-Hartmann wavefront sensor · Fragmented pupil · Low wind effect · Non-common path aberrations · High-contrast imaging

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High-contrast imaging with METIS

Cited by 10 publications

References 18 publications

Sulfur Hazes in Giant Exoplanet Atmospheres: Impacts on Reflected Light Spectra

Sulfur Hazes in Giant Exoplanet Atmospheres: Impacts on Reflected Light Spectra

End-to-end simulations of the E-ELT/METIS coronagraphs

Single conjugate adaptive optics for the ELT instrument METIS

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