Wind-driven halo in high-contrast images
Astronomy and Astrophysics, vol. 638, pp. A98
Abstract
Context.The wind-driven halo is a feature that is observed in images that were delivered by the latest generation of ground-based instruments that are equipped with an extreme adaptive optics system and a coronagraphic device, such as SPHERE at the Very Large Telescope (VLT). This signature appears when the atmospheric turbulence conditions vary faster than the adaptive optics loop can correct for. The wind-driven halo is observed as a radial extension of the point spread function along a distinct direction (this is sometimes referred to as the butterfly pattern). When this is present, it significantly limits the contrast capabilities of the instrument and prevents the extraction of signals at close separation or extended signals such as circumstellar disks. This limitation is consequential because it contaminates the data for a substantial fraction of the time: about 30% of the data produced by the VLT/SPHERE instrument are affected by the wind-driven halo. Aims.This paper reviews the causes of the wind-driven halo and presents a method for analyzing its contribution directly from the scientific images. Its effect on the raw contrast and on the final contrast after post-processing is demonstrated. Methods.We used simulations and on-sky SPHERE data to verify that the parameters extracted with our method can describe the wind-driven halo in the images. We studied the temporal, spatial, and spectral variation of these parameters to point out its deleterious effect on the final contrast. Results.The data-driven analysis we propose provides information to accurately describe the wind-driven halo contribution in the images. This analysis confirms that this is a fundamental limitation of the finally reached contrast performance. Conclusions.With the established procedure, we will analyze a large sample of data delivered by SPHERE in order to propose post-processing techniques that are tailored to removing the wind-driven halo.
Authors 12
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Max Planck Institute for Astronomy
Affiliation as printed
Max Planck Institute for Astronomy, Königstuhl 17, 69117 Heidelberg, Germany
MPIA - Max-Planck-Institut für Astronomie (Königstuhl 17, 69117 Heidelberg - Germany)
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University of New Hampshire · Durham University
Affiliation as printed
Centre for Advanced Instrumentation (CfAI), Department of Physics, Durham University, Durham DH1 3LE, UK
Department of Physics [Durham] (University of New Hampshire, 9 Library Way, Durham, NH 03824 - United States)
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Centre National de la Recherche Scientifique · Institut de Planétologie et d'Astrophysique de Grenoble · European Southern Observatory · Université Grenoble Alpes
Affiliation as printed
European Southern Observatory (ESO), Alonso de Córdova 3107, Vitacura, Casilla 19001, Santiago, Chile
Université Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France
ESO - European Southern Observatory [Santiago] (Casilla 19001, Santiago 19 - Chile)
IPAG - Institut de Planétologie et d'Astrophysique de Grenoble (414, Rue de la Piscine BP 53 38041 Grenoble Cedex 9 - France)
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University of New Hampshire · Durham University
Affiliation as printed
Centre for Advanced Instrumentation (CfAI), Department of Physics, Durham University, Durham DH1 3LE, UK
Department of Physics [Durham] (University of New Hampshire, 9 Library Way, Durham, NH 03824 - United States)
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Max Planck Institute for Astronomy
Affiliation as printed
Max Planck Institute for Astronomy, Königstuhl 17, 69117 Heidelberg, Germany
MPIA - Max-Planck-Institut für Astronomie (Königstuhl 17, 69117 Heidelberg - Germany)
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Centre National de la Recherche Scientifique · Aix-Marseille Université · W.M. Keck Observatory · Laboratoire d’Astrophysique de Marseille
Affiliation as printed
Aix Marseille Univ, CNRS, CNES, LAM, Marseille, France
W. M. Keck Observatory, 65-1120 Mamalahoa Highway, Kamuela, HI 96743, USA
LAM - Laboratoire d'Astrophysique de Marseille (Pôle de l'Étoile Site de Château-Gombert 38, rue Frédéric Joliot-Curie 13388 Marseille cedex 13 - France)
W.M. Keck Observatory (65-1120 Mamalahoa Hwy, Kamuela, HI 96743 - United States)
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Centre National de la Recherche Scientifique · Aix-Marseille Université · Laboratoire d’Astrophysique de Marseille
Affiliation as printed
Aix Marseille Univ, CNRS, CNES, LAM, Marseille, France
LAM - Laboratoire d'Astrophysique de Marseille (Pôle de l'Étoile Site de Château-Gombert 38, rue Frédéric Joliot-Curie 13388 Marseille cedex 13 - France)
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Max Planck Institute for Astronomy
Affiliation as printed
Max Planck Institute for Astronomy, Königstuhl 17, 69117 Heidelberg, Germany
MPIA - Max-Planck-Institut für Astronomie (Königstuhl 17, 69117 Heidelberg - Germany)
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University of New Hampshire · Durham University
Affiliation as printed
Centre for Advanced Instrumentation (CfAI), Department of Physics, Durham University, Durham DH1 3LE, UK
Department of Physics [Durham] (University of New Hampshire, 9 Library Way, Durham, NH 03824 - United States)
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Leiden University · Leiden Observatory
Affiliation as printed
Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands
Leiden Observatory [Leiden] (P.O. Box 9513, NL-2300 RA Leiden - Netherlands)
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Affiliation as printed
European Southern Observatory (ESO), Karl-Schwarzschild-Str. 2, 85748 Garching, Germany
ESO - European Southern Observatory (Karl-Schwarzchild Str. 2 D-85748 Garching bei München - Germany)
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Centre National de la Recherche Scientifique · Aix-Marseille Université · Laboratoire d’Astrophysique de Marseille
Affiliation as printed
Aix Marseille Univ, CNRS, CNES, LAM, Marseille, France
LAM - Laboratoire d'Astrophysique de Marseille (Pôle de l'Étoile Site de Château-Gombert 38, rue Frédéric Joliot-Curie 13388 Marseille cedex 13 - France)
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