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Published January 2017 | Published
Journal Article Open

The W. M. Keck Observatory Infrared Vortex Coronagraph and a First Image of HIP 79124 B


An optical vortex coronagraph has been implemented within the NIRC2 camera on the Keck II telescope and used to carry out on-sky tests and observations. The development of this new L'-band observational mode is described, and an initial demonstration of the new capability is presented: a resolved image of the low-mass companion to HIP 79124, which had previously been detected by means of interferometry. With HIP 79124 B at a projected separation of 186.5 mas, both the small inner working angle of the vortex coronagraph and the related imaging improvements were crucial in imaging this close companion directly. Due to higher Strehl ratios and more relaxed contrasts in L' band versus H band, this new coronagraphic capability will enable high-contrast, small-angle observations of nearby young exoplanets and disks on a par with those of shorter-wavelength extreme adaptive optics coronagraphs.

Additional Information

© 2017. The American Astronomical Society. Received 2016 August 3; revised 2016 October 26; accepted 2016 November 21; published 2017 January 4. We thank the Keck Science Steering Committee for their approval of this project, and especially J. Cohen for her support in getting this project off the drawing board. We also thank the director of the Caltech Optical Observatories, Shri Kulkarni, for providing test time for this new mode. Finally, we thank the W.M. Keck Observatory staff for their able and enthusiastic assistance with the observations. The data presented herein were obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W.M. Keck Foundation. The research leading to these results has received funding from the European Research Council under the European Union's Seventh Framework Programme (ERC Grant Agreement n. 337569), the French Community of Belgium through an ARC grant for Concerted Research Action, and the Swedish Research Council (VR) through project grant 621-2014-5959. Part of this work was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA.

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