| 1. |
- Absil, Olivier, et al.
(författare)
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An update on the VORTEX project
- 2015
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Ingår i: Techniques and Instrumentation for Detection of Exoplanets VII. - : SPIE.
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Konferensbidrag (refereegranskat)abstract
- In this talk, we will review the on-going activities within the VORTEX teamat the University of Liège and Uppsala University. The VORTEX project aimsto design, manufacture, test, and exploit vector vortex phase masks madeof sub-wavelength gratings (aka the Annular Groove Phase Mask, AGPM)for the direct detection and characterization of extrasolar planets. This talkwill specifically report on the commissioning of several AGPMs on infraredcameras equipping 10-m class telescopes, including the VLT, the LBT andthe Keck. We will describe the in-lab and on-sky performance of the AGPMs,and discuss first scientific observations. We will also report on the lessonslearned from the on-sky operation of our vortices, and discuss ways toimprove their performance. The potential of our coronagraphic devices inthe context of future extremely large telescopes and space missions will alsobe addressed.
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| 2. |
- Absil, Oliver, et al.
(författare)
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Three years of harvest with the vector vortex coronagraph in the thermal infrared
- 2016
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Ingår i: Ground-Based and Airborne Instrumentation for Astronomy VI. - : SPIE - International Society for Optical Engineering. - 9781510601963 ; , s. 1-14
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Konferensbidrag (refereegranskat)abstract
- For several years, we have been developing vortex phase masks based on sub-wavelength gratings, known as Annular Groove Phase Masks. Etched onto diamond substrates, these AGPMs are currently designed to be used in the thermal infrared (ranging from 3 to 13 μm). Our AGPMs were first installed on VLT/NACO and VLT/VISIR in 2012, followed by LBT/LMIRCam in 2013 and Keck/NIRC2 in 2015. In this paper, we review the development, commissioning, on-sky performance, and early scientific results of these new coronagraphic modes and report on the lessons learned. We conclude with perspectives for future developments and applications.
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| 3. |
- Carlomagno, Brunella, et al.
(författare)
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End-to-end simulations of the E-ELT/METIS coronagraphs
- 2016
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Ingår i: Adaptive Optics Systems V. - : SPIE - International Society for Optical Engineering. ; , s. 1-10
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Konferensbidrag (refereegranskat)abstract
- 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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| 4. |
- Carlomagno, Brunella, et al.
(författare)
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Performance evaluation of mid-IR vortex coronagraphs with centrally obscured segmented pupils
- 2015
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Konferensbidrag (refereegranskat)abstract
- In its original design, the E-ELT/Metis instrument envisages a vortex coronagraph in the mid-IR regime for detection and characterization of exoplanets, with a contrast of 1e-4 at 2 lambda/D (~40 mas in L band). The AGPM (Annular Groove Phase Mask) is a vortex phase mask with impressive characteristics: small inner working angle, high throughput, achromaticity. A non-perfectly circular pupil and non-flat input wavefront result in a starlight leakage, degrading the performance of the vortex coronagraph. In this work, we present end-to-end performance simulations using Fourier optical propagation to determine the quality of the starlight rejection obtained with an infrared vortex coronagraph. We first analyse the performance facing E-ELT pupil variations (segmentations, central obscuration, spiders, missing segments), then pointing jitter and random adaptive optics residual phase screens are introduced to derive more realistic performance. Finally, more advanced concepts of the infrared vortex coronagraph are presented, in order to compensate for performance degradation.
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| 5. |
- Delacroix, Christian, et al.
(författare)
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A family of subwavelength grating vortexcoronagraphs (SGVCs) with higher topological charge
- 2015
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Ingår i: Techniques and Instrumentation for Detection of Exoplanets VII. - : SPIE.
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Konferensbidrag (refereegranskat)abstract
- The subwavelength grating vortex coronagraph (SGVC) is a focal-planespiral-like phase mask whose key benefit is to allow high contrast imaging atsmall angles. Directly etched onto a CVD diamond substrate, it is well suitedto perform in the mid-infrared domain. It provides a continuous helicalphase ramp with a dark singularity in its center, and is characterized by itsnumber of phase revolutions, called the topological charge. Over the pasttwo years, we have manufactured several charge-2 SGVCs (a.k.a. annulargroove phase masks) and successfully demonstrated their performanceson 10-m class telescopes (LBT, VLT/NaCo, VLT/VISIR). To prevent stellarleakage on future 30-m class telescopes (E-ELT, TMT, GMT), a broaderoff-axis extinction is required, which can be achieved by increasing thetopological charge. We have recently proposed an original design for acharge-4 SGVC allowing less starlight to leak through the coronagraph, atthe cost of a degraded inner working angle. In this talk, we report on ourlatest development of higher charge SGVCs. From 3D rigorous numericalsimulations using a finite-difference time-domain (FDTD) algorithm, weConference 9605: Techniques and Instrumentationfor Detection of Exoplanets VIIR eturn to Contents +1 360 676 3290 · help@spie.org 647have derived a family of coronagraphs with higher topological charge(SGVC4/6/8). Our new optimization method addresses the principallimitation of such space-variant polarization state manipulation, i.e., theinconvenient discontinuities in the discrete grating pattern. The resultinggratings offer improved precision to the phase modulation compared toprevious designs. Finally, we present our preliminary manufacturing andmetrology results for infrared components down to the K-band.
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| 6. |
- Kaeufl, Hans Ulrich, et al.
(författare)
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NEAR : New Earths in the Alpha Cen Region (bringing VISIR as a "visiting instrument" to ESO-VLT-UT4)
- 2018
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Ingår i: Ground-Based And Airborne Instrumentation For Astronomy VII. - : SPIE. - 9781510619586
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Konferensbidrag (refereegranskat)abstract
- ESO in collaboration with the Breakthrough Initiatives, is adding a dedicated coronagraph to the Very Large Telescope mid-IR imager (VISIR) to further boost the high dynamic range imaging capability of this instrument. 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, even at wavelengths as long as 10 mu m, critically needs adaptive optics. 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 alpha-Cen(1) and alpha-Cen(2). Meaningful here means, achieving a contrast of approximate to 10(-6) within approximate to 0.8 arcsec from the star. Various measures to improve the sensitivity of VISIR will be applied, especially a dedicated filter, faster chopping and a Strehl-ratio close to 100% thanks to extreme adaptive optics. This should allow to detect a planet twice the diameter of Earth in 50 h on source integration time. 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 microwave background. For risk mitigation all components are being tested and quali fi ed under realistic conditions in the lab at ESO headquarters before integration into the instrument. The performance or suppression of the coronagraph is so good, that a non-thermal source (vulgo a laser) is needed on the test-bench. We will give an overview of the optical changes to VISIR, the implementation of wave front sensing, the Dicke switch design and laboratory testing, the AGPM design and laboratory testing, non common path error control with a ZELDA mask, sensitivity and contrast estimates, data flow and analysis, the overall project status, plan and outlook Needless to say that this project is of critical interest for future infrared instrumentation at the next generation of extremely large telescopes aiming at surveying the solar neighborhood for terrestrial planets by detecting and characterizing them based on their mid-IR fluxes.
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| 7. |
- Llop-Sayson, Jorge, et al.
(författare)
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Constraining the Orbit and Mass of epsilon Eridani b with Radial Velocities, Hipparcos IAD-Gaia DR2 Astrometry, and Multiepoch Vortex Coronagraphy Upper Limits
- 2021
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Ingår i: Astronomical Journal. - : Institute of Physics Publishing (IOPP). - 0004-6256 .- 1538-3881. ; 162:5
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Tidskriftsartikel (refereegranskat)abstract
- epsilon Eridani is a young planetary system hosting a complex multibelt debris disk and a confirmed Jupiter-like planet orbiting at 3.48 au from its host star. Its age and architecture are thus reminiscent of the early Solar System. The most recent study of Mawet et al., which combined radial-velocity data and Ms-band direct imaging upper limits, started to constrain the planet's orbital parameters and mass, but are still affected by large error bars and degeneracies. Here we make use of the most recent data compilation from three different techniques to further refine epsilon Eridani b's properties: RVs, absolute astrometry measurements from the Hipparcos and Gaia missions, and new Keck/NIRC2 Ms-band vortex coronagraph images. We combine this data in a Bayesian framework. We find a new mass, M-b = 0.66(-0.09)(+0.12) M-Jup, and inclination, i = 78.81(-22.41 degrees)(+29.34), with at least a factor 2 of improvement over previous uncertainties. We also report updated constraints on the longitude of the ascending node, the argument of the periastron, and the time of periastron passage. With these updated parameters, we can better predict the position of the planet at any past and future epoch, which can greatly help define the strategy and planning of future observations and with subsequent data analysis. In particular, these results can assist the search for a direct detection with JWST and the Nancy Grace Roman Space Telescope's coronagraph instrument.
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| 8. |
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| 9. |
- Wagner, Kevin, et al.
(författare)
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Imaging low-mass planets within the habitable zone of α Centauri
- 2021
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Ingår i: Nature Communications. - : Springer Nature. - 2041-1723. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- Giant exoplanets on wide orbits have been directly imaged around young stars. If the thermal background in the mid-infrared can be mitigated, then exoplanets with lower masses can also be imaged. Here we present a ground-based mid-infrared observing approach that enables imaging low-mass temperate exoplanets around nearby stars, and in particular within the closest stellar system, alpha Centauri. Based on 75-80% of the best quality images from 100h of cumulative observations, we demonstrate sensitivity to warm sub-Neptune-sized planets throughout much of the habitable zone of alpha Centauri A. This is an order of magnitude more sensitive than state-of-the-art exoplanet imaging mass detection limits. We also discuss a possible exoplanet or exozodiacal disk detection around alpha Centauri A. However, an instrumental artifact of unknown origin cannot be ruled out. These results demonstrate the feasibility of imaging rocky habitable-zone exoplanets with current and upcoming telescopes. Imaging of low-mass exoplanets can be achieved once the thermal background in the mid-infrared (MIR) wavelengths can be mitigated. Here, the authors present a ground-based MIR observing approach enabling imaging low-mass temperate exoplanets around nearby stars.
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| 10. |
- Wang, Jason J., et al.
(författare)
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Keck/NIRC2 L'-Band Imaging of Jovian-Mass Accreting Protoplanets around PDS 70
- 2020
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Ingår i: Astronomical Journal. - : American Astronomical Society. - 0004-6256 .- 1538-3881. ; 159:6
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Tidskriftsartikel (refereegranskat)abstract
- We present L'-band imaging of the PDS 70 planetary system with Keck/NIRC2 using the new infrared pyramid wave front sensor. We detected both PDS 70 b and c in our images, as well as the front rim of the circumstellar disk. After subtracting off a model of the disk, we measured the astrometry and photometry of both planets. Placing priors based on the dynamics of the system, we estimated PDS 70 b to have a semimajor axis of au and PDS 70 c to have a semimajor axis of au (95% credible interval). We fit the spectral energy distribution (SED) of both planets. For PDS 70 b, we were able to place better constraints on the red half of its SED than previous studies and inferred the radius of the photosphere to be 2–3 R Jup. The SED of PDS 70 c is less well constrained, with a range of total luminosities spanning an order of magnitude. With our inferred radii and luminosities, we used evolutionary models of accreting protoplanets to derive a mass of PDS 70 b between 2 and 4 M Jup and a mean mass accretion rate between 3 × 10−7 and 8 × 10−7 M Jup/yr. For PDS 70 c, we computed a mass between 1 and 3 M Jup and mean mass accretion rate between 1 × 10−7 and 5 × 10−7 M Jup/yr. The mass accretion rates imply dust accretion timescales short enough to hide strong molecular absorption features in both planets' SEDs.
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