Adaptive optics with an infrared pyramid wavefront sensor at Keck

Bond, C.; Cetre, Sylvain; Lilley, Scott; Wizinowich, Peter; Mawet, Dimitri; Chun, Mark; Wetherell, Edward; Jacobson, Shane; Lockhart, Charles; Warmbier, Eric; Ragland, Sam; Álvarez, Carlos; Guyon, Olivier; Goebel, Sean; Delorme, Jacques Robert; Jovanović, Nemanja; Hall, Donald N. B.; Wallace, J. Kent; Taheri, Mojtaba; Plantet, Cédric; Chambouleyron, Vincent

doi:10.1117/1.jatis.6.3.039003

Cited by 62 publications

(51 citation statements)

References 38 publications

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“…The Keck near-IR PyWFS (Bond et al 2020) corrected the wavefront at 1 kHz, correcting for 349 spatial modes and NIRC2 data (2020 December 25) was taken in the L p broadband filter (λ o = 3.78 μm).…”

Section: System Properties and Observationsmentioning

confidence: 99%

SCExAO/MEC and CHARIS Discovery of a Low-mass, 6 au Separation Companion to HIP 109427 Using Stochastic Speckle Discrimination and High-contrast Spectroscopy*

Steiger

Currie

Brandt

et al. 2021

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We report the direct imaging discovery of a low-mass companion to the nearby accelerating A star, HIP 109427, with the Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) instrument coupled with the Microwave Kinetic Inductance Detector Exoplanet Camera (MEC) and CHARIS integral field spectrograph. CHARIS data reduced with reference star point spread function (PSF) subtraction yield 1.1-2.4 μm spectra. MEC reveals the companion in Y and J band at a comparable signal-to-noise ratio using stochastic speckle discrimination, with no PSF subtraction techniques. Combined with complementary follow-up L p photometry from Keck/NIRC2, the SCExAO data favors a spectral type, effective temperature, and luminosity of M4-M5.5, 3000-3200 K, and

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Section: System Properties and Observationsmentioning

confidence: 99%

SCExAO/MEC and CHARIS Discovery of a Low-mass, 6 au Separation Companion to HIP 109427 Using Stochastic Speckle Discrimination and High-contrast Spectroscopy*

Steiger

Currie

Brandt

et al. 2021

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“…SAPHIRA detectors make use of electron-avalanche mechanisms within each pixel to effectively multiply the signal without increasing the read noise and thus improving the signal-to-noise ratio (S/N). SAPHIRA detectors allow for almost noiseless signal amplification and ultralow dark currents (Atkinson et al 2017), which is especially beneficial for ground-based astronomical observations of photon-starved targets (e.g., Goebel et al 2018;Bond et al 2020;Hippler et al 2020). This type of high-speed detector is particularly useful to minimize the degrading effect of the tip-tilt displacement on image quality by taking multiple short-exposure images while adding negligible noise (Jensen-Clem et al 2018).…”

Section: Infrared Cameramentioning

confidence: 99%

Large Adaptive Optics Survey for Substellar Objects around Young, Nearby, Low-mass Stars with Robo-AO

Salama

Baranec

et al. 2021

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We present results from the Large Adaptive optics Survey for Substellar Objects, where the goal is to directly image new substellar companions (<70 M Jup ) at wide orbital separations (50 au) around young (300 Myr), nearby (<100 pc), low-mass (≈0.1-0.8 M  ) stars. We report on 427 young stars imaged in the visible (i′) and nearinfrared (J or H ) simultaneously with Robo-AO on the Kitt Peak 2.1 m telescope and later the Maunakea University of Hawaii 2.2 m telescope. To undertake the observations, we commissioned a new infrared camera for Robo-AO that uses a low-noise high-speed SAPHIRA avalanche photodiode detector. We detected 121 companion candidates around 111 stars, of which 62 companions are physically associated based on Gaia DR2 parallaxes and proper motions, another 45 require follow-up observations to confirm physical association, and 14 are background objects. The companion separations range from 2 to 1101 au and reach contrast ratios of 7.7 mag in the nearinfrared compared to the primary. The majority of confirmed and pending candidates are stellar companions, with ∼5 being potentially substellar and requiring follow-up observations for confirmation. We also detected a 43±9 M Jup and an 81±5 M Jup companion that were previously reported. We found 34 of our targets have acceleration measurements detected using Hipparcos-Gaia proper motions. Of those, -+ 58 1412 % of the 12 stars with imaged companion candidates have significant accelerations (c > 11.8 2), while only -+ 23 6 11 % of the remaining 22 stars with no detected companion have significant accelerations. The significance of the acceleration decreases with increasing companion separation. These young accelerating low-mass stars with companions will eventually yield dynamical masses with future orbit monitoring.

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“…We compared this unsaturated PSF with the simulated ideal PSF at the L′ band, where we took into account throughput loss by the vortex mask (see Figure 1), and we obtained a Strehl ratio of ∼87% (approximately equivalent to the rms of the wave front errors ;200 nm). The current throughput of the NIRC2-PWFS is ∼9% and the maximum elevation of SR21 was ∼45°during our observations, which affected the AO performance compared with the ideal case (Bond et al 2018(Bond et al , 2020. The data were taken as a part of a shared-risk program using the NIR-PWFS (PI: Dimitri Mawet) which was aimed at science verification with redder targets.…”

Section: Observationsmentioning

confidence: 99%

“…However, for some specific science targets such as M-type stars or extincted young stellar objects (YSOs) that are faint at optical wavelengths while bright in the near-infrared (NIR), wave front sensing at NIR wavelengths provides better AO performance. Recently, an NIR pyramid wave front sensor (PWFS) was installed in the AO system at Keck II (Bond et al 2018(Bond et al , 2020 as part of the Keck Planet Imager and Characterizer (KPIC; Mawet et al 2016). Science operations using the NIR-PWFS with Keck/ NIRC2 began in early 2019.…”

Section: Introductionmentioning

confidence: 99%

Early High-contrast Imaging Results with Keck/NIRC2-PWFS: The SR 21 Disk

Uyama

Ren

Mawet

et al. 2020

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High-contrast imaging of exoplanets and protoplanetary disks depends on wavefront sensing and correction made by adaptive optics instruments. Classically, wavefront sensing has been conducted at optical wavelengths, which made high-contrast imaging of red targets such as M-type stars or extincted T Tauri stars challenging. Keck/NIRC2 has combined near-infrared (NIR) detector technology with the pyramid wavefront sensor (PWFS). With this new module we observed SR 21, a young star that is brighter at NIR wavelengths than at optical wavelengths. Compared with the archival data of SR 21 taken with the optical wavefront sensing we achieved ∼20% better Strehl ratio in similar natural seeing conditions. Further post-processing utilizing angular differential imaging and reference-star differential imaging confirmed the spiral feature reported by the VLT/SPHERE polarimetric observation, which is the first detection of the SR 21 spiral in total intensity at L band. We also compared the contrast limit of our result (10 −4 at 0. 4 and 2 × 10 −5 at 1. 0) with the archival data that were taken with optical wavefront sensing and confirmed the improvement, particularly at ≤ 0. 5. Our observation demonstrates that the NIR PWFS improves AO performance and will provide more opportunities for red targets in the future.

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Adaptive optics with an infrared pyramid wavefront sensor at Keck

Cited by 62 publications

References 38 publications

SCExAO/MEC and CHARIS Discovery of a Low-mass, 6 au Separation Companion to HIP 109427 Using Stochastic Speckle Discrimination and High-contrast Spectroscopy*

SCExAO/MEC and CHARIS Discovery of a Low-mass, 6 au Separation Companion to HIP 109427 Using Stochastic Speckle Discrimination and High-contrast Spectroscopy*

Large Adaptive Optics Survey for Substellar Objects around Young, Nearby, Low-mass Stars with Robo-AO

Early High-contrast Imaging Results with Keck/NIRC2-PWFS: The SR 21 Disk

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