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Journal articles on the topic 'Coronagraphie'

Author: Grafiati

Published: 7 July 2024

Last updated: 31 July 2025

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1

Yudaev, Andrey, Alexander Kiselev, Inna Shashkova, Alexander Tavrov, Alexander Lipatov, and Oleg Korablev. "Wavefront Sensing by a Common-Path Interferometer for Wavefront Correction in Phase and Amplitude by a Liquid Crystal Spatial Light Modulator Aiming the Exoplanet Direct Imaging." Photonics 10, no. 3 (2023): 320. http://dx.doi.org/10.3390/photonics10030320.

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We implemented the common-path achromatic interfero-coronagraph both for the wavefront sensing and the on-axis image component suppression, aiming for the stellar coronagraphy. A common-path achromatic interfero-coronagraph has its optical scheme based on a nulling rotational-shear interferometer. The angle of rotational shear can be chosen at a small angular extent of about 10 deg. Such a small angular shear maintains the coronagraphic contrast degradation known as the stellar leakage effect, caused by a finite stellar size. We study the phase and amplitude wavefront control by a liquid cryst

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Leboulleux, Lucie, Alexis Carlotti, and Mamadou N’Diaye. "Redundant apodization for direct imaging of exoplanets." Astronomy & Astrophysics 659 (March 2022): A143. http://dx.doi.org/10.1051/0004-6361/202142410.

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Context. Direct imaging and spectroscopy of Earth-like planets and young Jupiters require contrast values up to 106−1010 at angular separations of a few dozen milliarcseconds. To achieve this goal, one of the most promising approaches consists of using large segmented primary mirror telescopes with coronagraphic instruments. While they are able to reach high contrast at small angular separations, coronagraphs are highly sensitive to wavefront errors, however. The segmentation itself is responsible for phasing errors and segment-level vibrations that have to be controlled at a subnanometric acc

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3

Tokunaga, A. T., C. Ftaclas, J. R. Kuhn, and P. Baudoz. "High Dynamic Range and the Search for Planets." Symposium - International Astronomical Union 211 (2003): 487–96. http://dx.doi.org/10.1017/s0074180900211200.

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General arguments for optimized coronagraphy in the search for planets are presented. First, off-axis telescopes provide the best telescopic platforms for use with coronagraphy, and telescope fabrication technology now allows the fabrication of such telescopes with diameters of up to 6.5 m. We show that in certain circumstances a smaller telescope with an off-axis primary has a signal-to-noise advantage compared with larger Cassegrain telescopes. Second, to fully exploit the advantages of the coronagraph for suppressing stray light, it is necessary to use a high Strehl ratio adaptive optics sy

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Itoh, Satoshi, та Taro Matsuo. "A Coronagraph with a Sub-λ/D Inner Working Angle and a Moderate Spectral Bandwidth". Astronomical Journal 163, № 6 (2022): 279. http://dx.doi.org/10.3847/1538-3881/ac658a.

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Abstract Future high-contrast imaging spectroscopy with a large segmented telescope will be able to detect atmospheric molecules of Earth-like planets around G- or K-type main-sequence stars. Increasing the number of target planets will require a coronagraph with a small inner working angle (IWA), and wide spectral bandwidth is required if we enhance a variety of detectable atmospheric molecules. To satisfy these requirements, in this paper, we present a coronagraphic system that provides an IWA less than 1λ 0/D over a moderate wavelength band, where λ 0 is the design-center wavelength and D d

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5

Xin, Yinzi, Laurent Pueyo, Romain Laugier, et al. "Coronagraphic Data Post-processing Using Projections on Instrumental Modes." Astrophysical Journal 963, no. 2 (2024): 96. http://dx.doi.org/10.3847/1538-4357/ad1879.

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Abstract Directly observing exoplanets with coronagraphs is impeded by the presence of speckles from aberrations in the optical path, which can be mitigated in hardware with wave front control, as well as in post-processing. This work explores using an instrument model in post-processing to separate astrophysical signals from residual aberrations in coronagraphic data. The effect of wave front error (WFE) on the coronagraphic intensity consists of a linear contribution and a quadratic contribution. When either of the terms is much larger than the other, the instrument response can be approxima

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Leboulleux, Lucie, Jean-François Sauvage, Rémi Soummer, et al. "Experimental validation of coronagraphic focal-plane wavefront sensing for future segmented space telescopes." Astronomy & Astrophysics 639 (July 2020): A70. http://dx.doi.org/10.1051/0004-6361/202037658.

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Context. Direct imaging of Earth-like planets from space requires dedicated observatories, combining large segmented apertures with instruments and techniques such as coronagraphs, wavefront sensors, and wavefront control in order to reach the high contrast of 1010 that is required. The complexity of these systems would be increased by the segmentation of the primary mirror, which allows for the larger diameters necessary to image Earth-like planets but also introduces specific patterns in the image due to the pupil shape and segmentation and making high-contrast imaging more challenging. Amon

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Vigan, A., M. N’Diaye, K. Dohlen, et al. "Calibration of quasi-static aberrations in exoplanet direct-imaging instruments with a Zernike phase-mask sensor." Astronomy & Astrophysics 629 (August 26, 2019): A11. http://dx.doi.org/10.1051/0004-6361/201935889.

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Second-generation exoplanet imagers using extreme adaptive optics (ExAO) and coronagraphy have demonstrated their great potential for studying close circumstellar environments and for detecting new companions and helping to understand their physical properties. However, at very small angular separation, their performance in contrast is limited by several factors: diffraction by the complex telescope pupil (central obscuration and spiders) not perfectly canceled by the coronagraph, residual dynamic wavefront errors, chromatic wavefront errors, and wavefront errors resulting from noncommon path

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8

Song, Tengfei, Yu Liu, Xuefei Zhang, et al. "Toward Automated Coronal Observations: A New Integrated System Based on the Lijiang 10 cm Coronagraph." Universe 11, no. 5 (2025): 154. https://doi.org/10.3390/universe11050154.

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About ten years ago, we established the first coronagraph that has been continuously operating on the high plateau of western China. This coronagraph is an internal occulting, 10 cm aperture instrument, installed at Lijiang Station through a collaboration with the Norikura Station of the National Astronomical Observatory of Japan. To ensure high efficiency in current and future coronal observations, developing integrated observation systems is essential for reliable, autonomous, and remote operation of coronagraphs. This paper introduces an advanced integrated observation and control system, b

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9

Cagigas, Miguel A., Manuel P. Cagigal, Pedro J. Valle, Vidal F. Canales, Antonio Fuentes, and Roberto López. "Planetary system detection by estimating the covariance of coronagraphic lucky images." Monthly Notices of the Royal Astronomical Society 488, no. 3 (2019): 3262–67. http://dx.doi.org/10.1093/mnras/stz1954.

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ABSTRACT In this paper, we review two different methods to increase image contrast and propose the combination of both to detect faint companions surrounding a host star. Coronagraphy allows us to block light coming from the host star so that the residual star light can be reduced by several orders of magnitude. On the other hand, estimating the Covariance of Lucky Images (COELI) is a proven method to detect faint companions from ground-based telescope images. The dynamic range of the detection camera limits this technique. Hence, the application of COELI to coronagraphic images may increase t

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Clampin, Mark, John Krist, David R. Ardila, David A. Golimowski, Holland C. Ford, and Garth Illingworth. "ACS Coronagraphic Observations of Optically Thin Debris Disks." Symposium - International Astronomical Union 221 (2004): 449–57. http://dx.doi.org/10.1017/s0074180900241892.

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The Advanced Camera for Surveys (ACS) offers a coronagraphic imaging mode with angular resolution of 0.026″pixel−1. In combination with with the appropriate subtraction of reference star point spread functions (PSF) the coronagraph is capable of achieving contrast ratios of ∼1000. We present some of the first ACS observations of the optically thin debris disk HD141569A and discuss new results from these observations.

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11

Bos, S. P., D. S. Doelman, J. Lozi, et al. "Focal-plane wavefront sensing with the vector-Apodizing Phase Plate." Astronomy & Astrophysics 632 (November 26, 2019): A48. http://dx.doi.org/10.1051/0004-6361/201936062.

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Context. One of the key limitations of the direct imaging of exoplanets at small angular separations are quasi-static speckles that originate from evolving non-common path aberrations (NCPA) in the optical train downstream of the instrument’s main wavefront sensor split-off. Aims. In this article we show that the vector-Apodizing Phase Plate (vAPP) coronagraph can be designed such that the coronagraphic point spread functions (PSFs) can act as wavefront sensors to measure and correct the (quasi-)static aberrations without dedicated wavefront sensing holograms or modulation by the deformable mi

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12

Dube, Brandon D., A. J. Riggs, Brian D. Kern, et al. "Exascale integrated modeling of low-order wavefront sensing and control for the Roman Coronagraph instrument." Journal of the Optical Society of America A 39, no. 12 (2022): C133. http://dx.doi.org/10.1364/josaa.472364.

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Astronomical instruments to detect exoplanets require extreme wavefront stability. For these missions to succeed, comprehensive and precise modeling is required to design and analyze suitable coronagraphs and their wavefront control systems. In this paper, we describe techniques for integrated modeling at scale that is, to the best of our knowledge, 1000 times faster than previously published works. We show how this capability has been used to validate performance and perform uncertainty quantification for the Roman Coronagraph instrument. Finally, we show how this modeling capacity may be nec

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13

Galicher, R., E. Huby, P. Baudoz, and O. Dupuis. "A family of phase masks for broadband coronagraphy example of the wrapped vortex phase mask theory and laboratory demonstration." Astronomy & Astrophysics 635 (February 28, 2020): A11. http://dx.doi.org/10.1051/0004-6361/201936971.

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Context. Future instruments need efficient coronagraphs over large spectral ranges to enable broadband imaging or spectral characterization of exoplanets that are 108 times fainter than their star. Several solutions have been proposed. Pupil apodizers can attenuate the star intensity by a factor of 1010 but they only transmit a few percent of the light of the planet. Cascades of phase and/or amplitude masks can both attenuate the starlight and transmit most of the planet light, but the number of optics that require alignment makes this solution impractical for an instrument. Finally, vector ph

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14

Herscovici-Schiller, Olivier, Jean-François Sauvage, Laurent M. Mugnier, Kjetil Dohlen, and Arthur Vigan. "Coronagraphic phase diversity through residual turbulence: performance study and experimental validation." Monthly Notices of the Royal Astronomical Society 488, no. 3 (2019): 4307–16. http://dx.doi.org/10.1093/mnras/stz1986.

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Abstract Quasi-static aberrations in coronagraphic systems are the ultimate limitation to the capabilities of exoplanet imagers both ground-based and space-based. These aberrations – which can be due to various causes such as optics alignment or moving optical parts during the observing sequence – create light residuals called speckles in the focal plane. Those speckles might be mistaken for planets. For ground-based instruments, the presence of residual turbulent wavefront errors due to partial adaptive optics correction causes an additional difficulty to the challenge of measuring aberration

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Anche, Ramya M., Ewan Douglas, Kian Milani, et al. "Simulation of High-contrast Polarimetric Observations of Debris Disks with the Roman Coronagraph Instrument." Publications of the Astronomical Society of the Pacific 135, no. 1054 (2023): 125001. http://dx.doi.org/10.1088/1538-3873/ad0a72.

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Abstract The Nancy Grace Roman Space Telescope Coronagraph Instrument will enable the polarimetric imaging of debris disks and inner dust belts in the optical and near-infrared wavelengths, in addition to the high-contrast polarimetric imaging and spectroscopy of exoplanets. The Coronagraph uses two Wollaston prisms to produce four orthogonally polarized images and is expected to measure the polarization fraction with measurement errors <3% per spatial resolution element. To simulate the polarization observations through the Hybrid Lyot Coronagraph (HLC) and Shaped Pupil Coronagraph (SPC),

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Kim, I. S., and O. I. Bugaenko. "On magnetic measurements in prominences." Proceedings of the International Astronomical Union 8, S300 (2013): 426–27. http://dx.doi.org/10.1017/s1743921313011393.

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AbstractThe successes of magnetic measurements in faint objects located near very bright ones are strongly depending on the stray light in the telescope. We propose a mask with a variable transmission placed on the primary optics of a telescope. Our computations of the stray light in such a telescope indicate that the calculated coronagraphic factor of improvement, K, would increase at least by 2 orders of magnitude compared to the Lyot-type coronagraph.

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Bottom, Michael, J. Chris Shelton, James K. Wallace, et al. "Stellar Double Coronagraph: A Multistage Coronagraphic Platform at Palomar Observatory." Publications of the Astronomical Society of the Pacific 128, no. 965 (2016): 075003. http://dx.doi.org/10.1088/1538-3873/128/965/075003.

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18

Kenworthy, Matthew A., Sascha Quanz, Gilles Otten, et al. "Successes and challenges of the APP Coronagraph." Proceedings of the International Astronomical Union 8, S299 (2013): 40–41. http://dx.doi.org/10.1017/s1743921313007771.

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AbstractThe Apodizing Phase Plate (APP) coronagraph has been used to image the exoplanet β Pictoris b and the protoplanet candidate around HD 100546, and is currently in use in surveys with NaCo at the VLT. Its success is due to its tolerance to tip-tilt pointing errors in current AO systems, which degrade the performance of nearly all other coronagraphs. Currently the sensitivity of the APP is limited by non-common path errors in the science camera systems and by its chromatic behaviour. We present the achromatized Vector APP coronagraph and address how we will measure and minimise non-common

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Rivet, J. P., J. Gay, J. Dalmau, G. Cassar, and Y. Rabbia. "Stellar coronagraphy: laboratory testing of the Achromatic Interfero Coronagraph." Proceedings of the International Astronomical Union 1, no. C200 (2005): 485–88. http://dx.doi.org/10.1017/s1743921306009823.

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20

Vaughan, Sophia R., Timothy D. Gebhard, Kimberly Bott, et al. "Chasing rainbows and ocean glints: Inner working angle constraints for the Habitable Worlds Observatory." Monthly Notices of the Royal Astronomical Society 524, no. 4 (2023): 5477–85. http://dx.doi.org/10.1093/mnras/stad2127.

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ABSTRACT NASA is engaged in planning for a Habitable Worlds Observatory (HabWorlds ), a coronagraphic space mission to detect rocky planets in habitable zones and establish their habitability. Surface liquid water is central to the definition of planetary habitability. Photometric and polarimetric phase curves of starlight reflected by an exoplanet can reveal ocean glint, rainbows, and other phenomena caused by scattering by clouds or atmospheric gas. Direct imaging missions are optimized for planets near quadrature, but HabWorlds ’ coronagraph may obscure the phase angles where such optical f

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Baudoz, P., A. Boccaletti, Y. Rabbia, and J. Gay. "Stellar Coronagraphy: Study and Test of a Hybrid Interfero‐Coronagraph." Publications of the Astronomical Society of the Pacific 117, no. 835 (2005): 1004–11. http://dx.doi.org/10.1086/432565.

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22

Vogt, Frédéric P. A., Frantz Martinache, Olivier Guyon, et al. "Coronagraphic Low-Order Wavefront Sensor: Postprocessing Sensitivity Enhancer for High-Performance Coronagraphs." Publications of the Astronomical Society of the Pacific 123, no. 910 (2011): 1434–41. http://dx.doi.org/10.1086/663723.

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23

Mawet, Dimitri, and Pierre Riaud. "Subwavelength gratings for phase mask coronagraphy: the 4QZOG and AGPM coronagraphs." Proceedings of the International Astronomical Union 1, no. C200 (2005): 361–66. http://dx.doi.org/10.1017/s1743921306009598.

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Gay, J., J. P. Rivet, Y. Rabbia, et al. "Stellar coronagraphy: two mono-axial configurations for the Achromatic Interfero Coronagraph." Proceedings of the International Astronomical Union 1, no. C200 (2005): 473–76. http://dx.doi.org/10.1017/s1743921306009793.

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Por, E. H., and S. Y. Haffert. "The Single-mode Complex Amplitude Refinement (SCAR) coronagraph." Astronomy & Astrophysics 635 (March 2020): A55. http://dx.doi.org/10.1051/0004-6361/201731616.

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Context. The recent discovery of an Earth-mass exoplanet around the nearby star Proxima Centauri provides a prime target for the search for life on planets outside our solar system. Atmospheric characterization of these planets has been proposed by blocking the starlight with a stellar coronagraph and using a high-resolution spectrograph to search for reflected starlight off the planet. Aims. Due to the large flux ratio and small angular separation between Proxima b and its host star (≲10−7 and ≲2.2λ/D respectively; at 750 nm for an 8 m-class telescope) the coronagraph requires high starlight

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Mierla, M., B. Inhester, A. Antunes, et al. "On the 3-D reconstruction of Coronal Mass Ejections using coronagraph data." Annales Geophysicae 28, no. 1 (2010): 203–15. http://dx.doi.org/10.5194/angeo-28-203-2010.

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Abstract. Coronal Mass ejections (CMEs) are enormous eruptions of magnetized plasma expelled from the Sun into the interplanetary space, over the course of hours to days. They can create major disturbances in the interplanetary medium and trigger severe magnetic storms when they collide with the Earth's magnetosphere. It is important to know their real speed, propagation direction and 3-D configuration in order to accurately predict their arrival time at the Earth. Using data from the SECCHI coronagraphs onboard the STEREO mission, which was launched in October 2006, we can infer the propagati

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Bemporad, A., P. Pagano, and S. Giordano. "Measuring the electron temperatures of coronal mass ejections with future space-based multi-channel coronagraphs: a numerical test." Astronomy & Astrophysics 619 (November 2018): A25. http://dx.doi.org/10.1051/0004-6361/201833058.

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Context. The determination from coronagraphic observations of physical parameters of the plasma embedded in coronal mass ejections (CMEs) is of crucial importance for our understanding of the origin and evolution of these phenomena. Aims. The aim of this work is to perform the first ever numerical simulations of a CME as it will be observed by future two-channel (visible light VL and UV Ly-α) coronagraphs, such as the Metis instrument on-board ESA-Solar Orbiter mission, or any other future coronagraphs with the same spectral band-passes. These simulations are then used to test and optimize the

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Sasso, C., R. F. Pinto, V. Andretta, et al. "Comparing extrapolations of the coronal magnetic field structure at 2.5R⊙with multi-viewpoint coronagraphic observations." Astronomy & Astrophysics 627 (June 25, 2019): A9. http://dx.doi.org/10.1051/0004-6361/201834125.

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The magnetic field shapes the structure of the solar corona, but we still know little about the interrelationships between the coronal magnetic field configurations and the resulting quasi-stationary structures observed in coronagraphic images (such as streamers, plumes, and coronal holes). One way to obtain information on the large-scale structure of the coronal magnetic field is to extrapolate it from photospheric data and compare the results with coronagraphic images. Our aim is to verify whether this comparison can be a fast method to systematically determine the reliability of the many me

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Yudaev, A. V., I. A. Shashkova, A. V. Kiselev, A. A. Komarova, and A. V. Tavrov. "Korrektsiya volnovogo fronta dlya nablyudeniya ekzoplanety na fone difraktsionnoy okrestnosti zvezdy." Журнал экспериментальной и теоретической физики 163, no. 2 (2023): 131–52. http://dx.doi.org/10.31857/s0044451023020013.

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We propose and investigate a precise wavefront correction method for the astronomical observation of exoplanets in the diffraction stellar vicinity. We show the applicability of the method for measuring and correcting the wavefront in the scheme of a telescope and an interferometric coronagraph without applying any Hartmann wavefront sensors. In our laboratory experiment we achieved a correction accuracy ~λ/50 and a coronagraphic contrast better than 105. We outline the prospects for increasing the correction accuracy to a target value of λ/500 to visualize the Earth in the vicinity of the Sun

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Shan 单, Jiahui 家辉, Huapeng 化鹏 Zhang 张, Lei 磊. Lu 卢, et al. "CAMEL. II. A 3D Coronal Mass Ejection Catalog Based on Coronal Mass Ejection Automatic Detection with Deep Learning." Astrophysical Journal Supplement Series 272, no. 1 (2024): 18. http://dx.doi.org/10.3847/1538-4365/ad37bc.

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Abstract Coronal mass ejections (CMEs) are major drivers of geomagnetic storms, which may cause severe space weather effects. Automating the detection, tracking, and three-dimensional (3D) reconstruction of CMEs is important for operational predictions of CME arrivals. The COR1 coronagraphs on board the Solar Terrestrial Relations Observatory spacecraft have facilitated extensive polarization observations, which are very suitable for the establishment of a 3D CME system. We have developed such a 3D system comprising four modules: classification, segmentation, tracking, and 3D reconstructions.

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Kühn, J., E. Serabyn, J. Lozi, et al. "An H-band Vector Vortex Coronagraph for the Subaru Coronagraphic Extreme Adaptive Optics System." Publications of the Astronomical Society of the Pacific 130, no. 985 (2018): 035001. http://dx.doi.org/10.1088/1538-3873/aa9fe5.

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Song, Hongqiang, Leping Li, Zhenjun Zhou, Lidong Xia, Xin Cheng, and Yao Chen. "The Structure of Coronal Mass Ejections Recorded by the K-Coronagraph at Mauna Loa Solar Observatory." Astrophysical Journal Letters 952, no. 1 (2023): L22. http://dx.doi.org/10.3847/2041-8213/ace422.

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Abstract Previous survey studies reported that coronal mass ejections (CMEs) can exhibit various structures in white-light coronagraphs, and ∼30% of them have the typical three-part feature in the high corona (e.g., 2–6 R ⊙), which has been taken as the prototypical structure of CMEs. It is widely accepted that CMEs result from eruption of magnetic flux ropes (MFRs), and the three-part structure can be understood easily by means of the MFR eruption. It is interesting and significant to answer why only ∼30% of CMEs have the three-part feature in previous studies. Here we conduct a synthesis of

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Loutsenko, Igor, and Oksana Yermolayeva. "Quasi-Band-Limited Coronagraph for Extended Sources." Journal of Astronomical Instrumentation 10, no. 01 (2021): 2150002. http://dx.doi.org/10.1142/s2251171721500021.

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We propose a class of graded coronagraphic “amplitude” image masks for a high throughput Lyot-type coronagraph that transmits light from an annular region around an extended source and suppresses light, with extremely high ratio, from elsewhere. The interior radius of the region is comparable with its exterior radius. The masks are designed using an idea inspired by approach due M. J. Kuchner and W. A. Traub (“band-limited” masks) and approach to optimal apodization by D. Slepian. One potential application of our masks is direct high-resolution imaging of exo-planets with the help of the Solar

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Smartt, Raymond N., Serge Koutchmy, and Jacques-Clair NoëNs. "Near-IR Solar Coronal Observations with New-Technology Reflecting Coronographs." Symposium - International Astronomical Union 154 (1994): 603–8. http://dx.doi.org/10.1017/s0074180900124908.

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Emission-line and K-coronal observations in the IR have the significant advantage of reduced sky brightness compared with the visible, while the effects of seeing are also reduced. Moreover, strong lines are available in the near-IR. Examples of the current capabilities of IR coronal observations using conventional Lyot coronagraphs are discussed briefly. Photometric measurements using the two IR lines of Fe XIII (10,747 Å and 10,798 Å), together with the Fe XIII 3,388 Å line, have provided a valuable electron-density diagnostic, but with low-angular-resolution. The 10,747 Å line has high intr

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Schmid, H. M., A. Bazzon, R. Roelfsema, et al. "SPHERE/ZIMPOL high resolution polarimetric imager." Astronomy & Astrophysics 619 (November 2018): A9. http://dx.doi.org/10.1051/0004-6361/201833620.

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Context. The SPHERE “planet finder” is an extreme adaptive optics (AO) instrument for high resolution and high contrast observations at the Very Large Telescope (VLT). We describe the Zurich Imaging Polarimeter (ZIMPOL), the visual focal plane subsystem of SPHERE, which pushes the limits of current AO systems to shorter wavelengths, higher spatial resolution, and much improved polarimetric performance. Aims. We present a detailed characterization of SPHERE/ZIMPOL which should be useful for an optimal planning of observations and for improving the data reduction and calibration. We aim to provi

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Guyon, Olivier, Taro Matsuo, and Roger Angel. "CORONAGRAPHIC LOW-ORDER WAVE-FRONT SENSOR: PRINCIPLE AND APPLICATION TO A PHASE-INDUCED AMPLITUDE CORONAGRAPH." Astrophysical Journal 693, no. 1 (2009): 75–84. http://dx.doi.org/10.1088/0004-637x/693/1/75.

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Liu, Yu, and Xuefei Zhang. "The coronal green line monitoring: a traditional but powerful tool for coronal physics." Proceedings of the International Astronomical Union 13, S340 (2018): 169–70. http://dx.doi.org/10.1017/s1743921318001382.

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AbstractThe particular environment with high temperature and low plasma density in the corona results to the formation of some forbidden emission lines, in which the well-known green line at 530.3 nm has been utilized to diagnose the corona for a few decades. For the green line, besides its contribution on revealing the long-term coronal cycles as well as their relationship to the other solar phenomena, it is also helpful to detect limb coronal waves and ejections originated from the lower corona which seems not to be paid close attention to. Suggestions are presented that we not only need to

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Morgan, Rachel E., Ewan S. Douglas, Gregory W. Allan, et al. "MEMS Deformable Mirrors for Space-Based High-Contrast Imaging." Micromachines 10, no. 6 (2019): 366. http://dx.doi.org/10.3390/mi10060366.

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Micro-Electro-Mechanical Systems (MEMS) Deformable Mirrors (DMs) enable precise wavefront control for optical systems. This technology can be used to meet the extreme wavefront control requirements for high contrast imaging of exoplanets with coronagraph instruments. MEMS DM technology is being demonstrated and developed in preparation for future exoplanet high contrast imaging space telescopes, including the Wide Field Infrared Survey Telescope (WFIRST) mission which supported the development of a 2040 actuator MEMS DM. In this paper, we discuss ground testing results and several projects whi

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Lucas, Miles, Barnaby Norris, Olivier Guyon, et al. "Visible-light High-contrast Imaging and Polarimetry with SCExAO/VAMPIRES." Publications of the Astronomical Society of the Pacific 136, no. 11 (2024): 114504. http://dx.doi.org/10.1088/1538-3873/ad89af.

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Abstract We present significant upgrades to the Visible Aperture-Masking Polarimetric Imager/Interferometer for Resolving Exoplanetary Signatures (VAMPIRES) instrument, a visible-light (600–800 nm) high-contrast imaging polarimeter integrated within SCExAO on the Subaru telescope. Key enhancements include new qCMOS detectors, coronagraphs, polarization optics, and a multiband imaging mode, improving sensitivity, resolution, and efficiency. These upgrades position VAMPIRES as a powerful tool for studying sub-stellar companions, accreting protoplanets, circumstellar disks, stellar jets, stellar

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Rahman, Sumiaya, Seungheon Shin, Hyun-jin Jeong, et al. "Fast Reconstruction of 3D Density Distribution around the Sun Based on the MAS by Deep Learning." Astrophysical Journal 948, no. 1 (2023): 21. http://dx.doi.org/10.3847/1538-4357/acbd3c.

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Abstract This study is the first attempt to generate a three-dimensional (3D) coronal electron density distribution based on the pix2pixHD model, whose computing time is much shorter than that of the magnetohydrodynamic (MHD) simulation. For this, we consider photospheric solar magnetic fields as input, and electron density distribution simulated with the MHD Algorithm outside a Sphere (MAS) at a given solar radius is taken as output. We consider 155 pairs of Carrington rotations as inputs and outputs from 2010 June to 2022 April for training and testing. We train 152 deep-learning models for

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Poletto, G., A. Bemporad, F. Landini, and M. Romoli. "Reconnection in a slow Coronal Mass Ejection." Annales Geophysicae 26, no. 10 (2008): 3067–75. http://dx.doi.org/10.5194/angeo-26-3067-2008.

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Abstract. This paper aims at studying reconnection occurring in the aftermath of the 28 May 2004, CME, first imaged by the LASCO (Large Angle and Spectrometric Coronagraph) C2 at 11:06 UT. The CME was observed in White Light and UV radiation: images acquired by the LASCO C2 and C3 coronagraphs and spectra acquired by UVCS (Ultraviolet Coronagraph Spectrometer) allowed us to identify the level at which field lines, stretched outwards by the CME ejection, reconnect below the CME bubble. As the CME propagates outwards, reconnection occurs at increasingly higher levels. The process goes on at a lo

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Xin, Yinzi, Nemanja Jovanovic, Garreth Ruane, et al. "Efficient Detection and Characterization of Exoplanets within the Diffraction Limit: Nulling with a Mode-selective Photonic Lantern." Astrophysical Journal 938, no. 2 (2022): 140. http://dx.doi.org/10.3847/1538-4357/ac9284.

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Abstract Coronagraphs allow for faint off-axis exoplanets to be observed, but are limited to angular separations greater than a few beam widths. Accessing closer-in separations would greatly increase the expected number of detectable planets, which scales inversely with the inner working angle. The vortex fiber nuller (VFN) is an instrument concept designed to characterize exoplanets within a single beam width. It requires few optical elements and is compatible with many coronagraph designs as a complementary characterization tool. However, the peak throughput for planet light is limited to ab

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Sanghi, Aniket, Charles Beichman, Dimitri Mawet та ін. "A Preliminary Search for Planets and Exozodiacal Emission Around α Centauri A with JWST/MIRI". Research Notes of the AAS 9, № 5 (2025): 119. https://doi.org/10.3847/2515-5172/add880.

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Abstract We present F1550C (15.5 μm) coronagraphic imaging observations of the nearest solar-type star α Cen A using the James Webb Space Telescope (JWST) Mid-InfraRed Instrument (MIRI). The observations, executed in 2025 February, were compromised by having only one successful roll and degraded performance due to a position mismatch (Δr ∼ 10 mas) between α Cen A and the best-matching reference observation behind the MIRI coronagraph. We set preliminary upper limits on both the presence of a planet and an exozodiacal dust disk. The observations are sensitive to a planet heated by α Cen A (200–

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Low, B. C. "The Dynamics of Solar Coronal Magnetic Fields." Symposium - International Astronomical Union 140 (1990): 13–15. http://dx.doi.org/10.1017/s0074180900189387.

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The solar corona is a hot (106K) highly ionized plasma structured by its magnetic field into open regions where the solar wind escapes and closed regions where relatively dense plasma is trapped in near static equilibrium. Observed in Thomson-scattered light at times of solar eclipse or by artificial occultation using a coronagraph, these closed regions show up conspicuously as helmet-shaped bright structures. The large scale corona evolves in time in response to the solar dynamo that continually injects new magnetic flux into the corona with the eventual reversal of the global magnetic polari

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Slemzin, V., O. Bougaenko, A. Ignatiev, et al. "Off-limb EUV observations of the solar corona and transients with the CORONAS-F/SPIRIT telescope-coronagraph." Annales Geophysicae 26, no. 10 (2008): 3007–16. http://dx.doi.org/10.5194/angeo-26-3007-2008.

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Abstract. The SPIRIT telescope aboard the CORONAS-F satellite (in orbit from 26 July 2001 to 5 December 2005), observed the off-limb solar corona in the 175 Å (Fe IX, X and XI lines) and 304 Å (He II and Si XI lines) bands. In the coronagraphic mode the mirror was tilted to image the corona at the distance of 1.1...5 Rsun from the solar center, the outer occulter blocked the disk radiation and the detector sensitivity was enhanced. This intermediate region between the fields of view of ordinary extreme-ultraviolet (EUV) telescopes and most of the white-light (WL) coronagraphs is responsible fo

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St. Cyr, O. C., and T. Warner. "SMM Coronagraph Observations of Particulate Contamination." International Astronomical Union Colloquium 112 (1991): 126–38. http://dx.doi.org/10.1017/s0252921100003870.

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ABSTRACTSome recent images taken by the white light coronagraph telescope aboard the Solar Maximum Mission (SMM) observatory show bright streaks that are apparently caused by particles associated with the spacecraft. In this report we describe these observations, and we analyze the times of their occurrence. We demonstrate that the sightings occur most often near SMM’s orbital dawn, and we speculate that thermal shock is the mechanism that produces the particles. Although these sightings have not seriously affected the coronagraph’s scientific operations, the unexpected passage of bright mater

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Greenbaum, Alexandra Z., Jorge Llop-Sayson, Ben W. P. Lew, et al. "First Observations of the Brown Dwarf HD 19467 B with JWST." Astrophysical Journal 945, no. 2 (2023): 126. http://dx.doi.org/10.3847/1538-4357/acb68b.

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Abstract We observed HD 19467 B with JWST’s NIRCam in six filters spanning 2.5–4.6 μm with the long-wavelength bar coronagraph. The brown dwarf HD 19467 B was initially identified through a long-period trend in the radial velocity of the G3V star HD 19467. HD 19467 B was subsequently detected via coronagraphic imaging and spectroscopy, and characterized as a late-T type brown dwarf with an approximate temperature ∼1000 K. We observed HD 19467 B as a part of the NIRCam GTO science program, demonstrating the first use of the NIRCam Long Wavelength Bar coronagraphic mask. The object was detected

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Bemporad, A., S. Pennella, K. Battams, et al. "Analysis of the first coronagraphic multi-band observations of a sungrazing comet." Astronomy & Astrophysics 680 (December 2023): A90. http://dx.doi.org/10.1051/0004-6361/202346881.

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Context. Between 24 and 25 December 2021 a sungrazing comet (SOHO-4341) approached the Sun, being observed by “classical” visible light (VL) coronagraphs on board the SOHO and STEREO missions, and also by the innovative Metis coronagraph on board the ESA-NASA Solar Orbiter mission in the VL and ultraviolet (UV H I Lyman-α) band. Aims. We show how VL data acquired by the Metis coronagraph can be combined with those provided by other space-based coronagraphs to reconstruct the comet orbit, but also to provide information on the dust composition from the polarized VL emission. Moreover, we show h

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Herscovici-Schiller, O., L. M. Mugnier, P. Baudoz, R. Galicher, J. F. Sauvage, and B. Paul. "Experimental validation of joint phase and amplitude wave-front sensing with coronagraphic phase diversity for high-contrast imaging." Astronomy & Astrophysics 614 (June 2018): A142. http://dx.doi.org/10.1051/0004-6361/201732439.

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Context. The next generation of space-borne instruments dedicated to the direct detection of exoplanets requires unprecedented levels of wavefront control precision. Coronagraphic wavefront sensing techniques for these instruments must measure both the phase and amplitude of the optical aberrations using the scientific camera as a wavefront sensor. Aims. In this paper, we develop an extension of coronagraphic phase diversity to the estimation of the complex electric field, that is, the joint estimation of phase and amplitude. Methods. We introduced the formalism for complex coronagraphic phase

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Qian, Lulu, Min Huang, Wenhao Zhao, et al. "High-Precision Pointing and Tracking System Design for Near-Space Balloon-Based Optical Observation." Applied Sciences 14, no. 15 (2024): 6531. http://dx.doi.org/10.3390/app14156531.

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Near-space high-altitude balloon-based platforms have a series of advantages and provide superior conditions for optical observation. In order to ensure the stability of the optical axis of the optical detection load and stable tracking of the target, a near-space high-altitude balloon-based high-precision pointing and tracking system was designed, which can compensate for changes in the pitch angle and azimuth angle of the platform during flight. The system includes a primary platform stable pointing system and a secondary precise tracking system. In the finished flight experiment, the primar

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