scholarly journals Adaptive Optics Imaging of Circumstellar Environments

2004 ◽  
Vol 221 ◽  
pp. 307-312
Author(s):  
Dániel Apai ◽  
Ilaria Pascucci ◽  
Hongchi Wang ◽  
Wolfgang Brandner ◽  
Thomas Henning ◽  
...  
Keyword(s):  
High Resolution ◽  
Adaptive Optics ◽  
Near Infrared ◽  
Infrared Imaging ◽  
Circumstellar Disks ◽  
Circumstellar Envelope ◽  
High Contrast ◽  
Contrast Imaging ◽  
High Contrast Imaging ◽  
Circumstellar Environments

We present results from our high-resolution, high-contrast imaging campaign targeting the circumstellar environments of young, nearby stars of different masses. The observations have been conducted using the ALFA/CA 3.5m and NACO UT4/VLT adaptive optics systems. In order to enhance the contrast we applied the methods PSF-subtraction and polarimetric differential imaging (PDI). The observations of young stars yielded the identification of numerous new companion candidates, the most interesting one being ∼ 0.5″ from FU Ori. We also obtained high-resolution near-infrared imaging of the circumstellar envelope of SU Aur and AB Aur. Our PDI of the TW Hya circumstellar disk traced back the disk emission as close as 0.1″ ≃ 6 AU from the star, the closest yet. Our results demonstrate the potential of the adaptive optics systems in achieving high-resolution and high-contrast imaging and thus in the study of circumstellar disks, envelopes and companions.

scholarly journals Origin of the asymmetry of the wind driven halo observed in high-contrast images

2018 ◽  
Vol 620 ◽  
pp. L10 ◽  
Author(s):  
F. Cantalloube ◽  
E. H. Por ◽  
K. Dohlen ◽  
J.-F. Sauvage ◽  
A. Vigan ◽  
...  
Keyword(s):  
Adaptive Optics ◽  
Predictive Control ◽  
Near Infrared ◽  
Control Algorithms ◽  
Circumstellar Disk ◽  
High Contrast ◽  
Contrast Imaging ◽  
High Contrast Imaging ◽  
The Asymmetry ◽  
Processing Techniques

The latest generation of high-contrast instruments dedicated to exoplanets and circumstellar disk imaging are equipped with extreme adaptive optics and coronagraphs to reach contrasts of up to 10−4 at a few tenths of arcseconds in the near-infrared. The resulting image shows faint features, only revealed with this combination, such as the wind driven halo. The wind driven halo is due to the lag between the adaptive optics correction and the turbulence speed over the telescope pupil. However, we observe an asymmetry of this wind driven halo that was not expected when the instrument was designed. In this letter, we describe and demonstrate the physical origin of this asymmetry and support our explanation by simulating the asymmetry with an end-to-end approach. From this work, we find that the observed asymmetry is explained by the interference between the AO-lag error and scintillation effects, mainly originating from the fast jet stream layer located at about 12 km in altitude. Now identified and interpreted, this effect can be taken into account for further design of high-contrast imaging simulators, next generation or upgrade of high-contrast instruments, predictive control algorithms for adaptive optics, or image post-processing techniques.

scholarly journals A high-contrast imaging survey of nearby red supergiants

2016 ◽  
Vol 12 (S329) ◽  
pp. 166-170
Author(s):  
Peter Scicluna ◽  
Ralf Siebenmorgen ◽  
Joris Blommaert ◽  
Francisca Kemper ◽  
Roger Wesson ◽  
...  
Keyword(s):  
Mass Loss ◽  
Adaptive Optics ◽  
Near Infrared ◽  
Infrared Imaging ◽  
Contrast Imaging ◽  
High Contrast Imaging ◽  
Show Evidence ◽  
Red Supergiants ◽  
Nearby Stars ◽  
Discrete Mass

AbstractMass-loss in cool supergiants remains poorly understood, but is one of the key elements in their evolution towards exploding as supernovae. Some show evidence of asymmetric mass loss, discrete mass-ejections and outbursts, with seemingly little to distinguish them from more quiescent cases. To explore the prevalence of discrete ejections and companions we have conducted a high-constrast survey using near-infrared imaging and optical polarimetric imaging of nearby southern and equatorial red supergiants, using the extreme adaptive optics instrument SPHERE, which was designed to image planets around nearby stars. We present the initial results of this survey, including the detection of large (500 nm) dust grains in the ejecta of VY CMa and a candidate dusty torus aligned with the maser ring of VX Sgr. We briefly speculate on the consequences for our understanding of mass loss in these extreme stars.

scholarly journals Direct imaging and spectroscopy of exoplanets with the ELT/HARMONI high-contrast module

2021 ◽  
Author(s):  
Mathis Houllé ◽  
Arthur Vigan ◽  
Alexis Carlotti ◽  
Élodie Choquet ◽  
Faustine Cantalloube ◽  
...  
Keyword(s):  
Adaptive Optics ◽  
Near Infrared ◽  
Direct Detection ◽  
Imaging Techniques ◽  
High Contrast ◽  
Contrast Imaging ◽  
High Contrast Imaging ◽  
Medium Resolution ◽  
Imaging And Spectroscopy ◽  
Integral Field Spectrograph

<p>Combining high-contrast imaging with medium-resolution spectroscopy has recently been shown to significantly boost the direct detection of exoplanets. In this optic, HARMONI, one of the first-light instruments to be mounted on ESO's ELT, will be equipped with a single-conjugated adaptive optics system to reach the diffraction limit of the ELT in H and K bands, a high-contrast module dedicated to exoplanet imaging, and a medium-resolution (up to R = 17 000) optical and near-infrared integral field spectrograph. When combined, these systems will provide unprecedented contrast limits at separations between 50 and 400 mas. We will present in this talk the results of extensive simulations of exoplanet observations with the HARMONI high-contrast module. We used an end-to-end model of the instrument to simulate observations based on realistic observing scenarios and conditions. We then analyzed these observations with the so-called "molecule mapping" technique, which has shown in recent studies its efficiency to disentangle planetary companions from their host star and boost their signal. Although HARMONI has not been fully designed for high-contrast imaging, we will show that it should greatly outperform the current dedicated instruments, such as SPHERE on the VLT. We detect planets above 5σ in 2 hours at contrasts up to 16 mag and separations down to 75 mas in several spectral configurations of the instrument. Simulating planets from population synthesis models, we could image in this amount of time companions as close as 1 AU from a host star at 30 pc and as light as 2 M<sub>Jup</sub>. We show that taking advantage of the combination of high-contrast imaging and medium-resolution spectroscopy through molecule mapping allows us to access much fainter planets (up to 2.5 mag) than the standard high-contrast imaging techniques. We also demonstrate that HARMONI should be available for near-critical exoplanet observations with this method during 60 to 70% of telescope time at the ELT.</p>

Realizing the Potential of JWST High Contrast Imaging with Coronagraphic Phase-Retrieval

2021 ◽  
Author(s):  
Marie Ygouf ◽  
Charles A Beichman ◽  
Graça M Rocha ◽  
Joseph J Green ◽  
Jewell Jeffrey B ◽  
...  
Keyword(s):  
Phase Retrieval ◽  
High Contrast ◽  
California Institute ◽  
Systematic Observation ◽  
Contrast Imaging ◽  
Space Telescope ◽  
California Institute Of Technology ◽  
High Contrast Imaging ◽  
Circumstellar Environments ◽  
Institute Of Technology

<div>  The James Webb Space Telescope (JWST) will probe circumstellar environments at an unprecedented sensitivity. However, the performance of high-contrast imaging instruments is limited by the residual light from the star at close separations (<2-3”), where the incidence of exoplanets increases rapidly. There is currently no solution to get rid of the residual light down to the photon noise level at those separations, which may prevent some crucial discoveries.</div> <div>  We are further developing and implementing a potentially game-changing technique of post-processing that does not require the systematic observation of a reference star, but instead directly uses data from the science target by taking advantage of the technique called “phase retrieval”. This technique is built on a Bayesian framework that provides a more robust determination of faint astrophysical structures around a bright source.</div> <div>  This approach uses a model of instrument that takes advantage of prior information, such as data from wavefront sensing operations on JWST, to estimate instrumental aberrations and further push the limits of high-contrast imaging. With this approach, our goal is to improve the contrast that can be achieved with JWST instruments.</div> <div>  We were awarded a JWST GO-Calibration proposal to implement, test and validate this approach on NIRCam imaging and coronagraphic imaging. This work will pave the way for the future space-based high-contrast imaging instruments such as the Nancy Grace Roman Space Telescope Coronagraph Instrument (Roman CGI). This technique will be crucial to make the best use of the telemetry data that will be collected during the CGI operations.</div> <div>  <br />“© 2021 California Institute of Technology. Government sponsorship acknowledged. The research was carried out in part at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. This document has been reviewed and determined not to contain export controlled data.”</div>

High Contrast Imaging for Python (HCIPy): an open-source adaptive optics and coronagraph simulator

2018 ◽  
Author(s):  
Emiel H. Por ◽  
Sebastiaan Y. Haffert ◽  
Vikram Mark Radhakrishnan ◽  
David S. Doelman ◽  
Maaike van Kooten ◽  
...  
Keyword(s):  
Open Source ◽  
Adaptive Optics ◽  
High Contrast ◽  
Contrast Imaging ◽  
High Contrast Imaging

scholarly journals precision: a fast python pipeline for high-contrast imaging – application to SPHERE observations of the red supergiant VX Sagitariae

2020 ◽  
Vol 494 (3) ◽  
pp. 3200-3211
Author(s):  
P Scicluna ◽  
F Kemper ◽  
R Siebenmorgen ◽  
R Wesson ◽  
J A D L Blommaert ◽  
...  
Keyword(s):  
Near Infrared ◽  
Extrasolar Planets ◽  
Asymmetric Structure ◽  
High Contrast ◽  
Contrast Imaging ◽  
Near Ir ◽  
High Contrast Imaging ◽  
Infrared Imager ◽  
Imaging Application ◽  
Efficient Reduction

ABSTRACT The search for extrasolar planets has driven rapid advances in instrumentation, resulting in cameras such as SPHERE at the VLT, GPI at Gemini South and SCExAO at Subaru, capable of achieving very high contrast (∼106) around bright stars with small inner working angles (${\sim}0.1\,{\rm arcsec}$). The optimal exploitation of data from these instruments depends on the availability of easy-to-use software to process and analyse their data products. We present a pure-python pipeline, precision, which provides fast, memory-efficient reduction of data from the SPHERE/IRDIS near-infrared imager, and can be readily extended to other instruments. We apply precision to observations of the extreme red supergiant VX Sgr, the inner outflow of which is revealed to host complex, asymmetric structure in the near-IR. In addition, optical polarimetric imaging reveals clear extended polarized emission on ∼0.5 arcsec scales that varies significantly with azimuth, confirming the asymmetry. While not conclusive, this could suggest that the ejecta are confined to a disc or torus, which we are viewing nearly face on, although other non-spherical or clumpy configurations remain possible. VX Sgr has no known companions, making such a geometry difficult to explain, as there is no obvious source of angular momentum in the system.

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