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Reference Star Differential Imaging of Close-in Companions and Circumstellar Disks with the NIRC2 Vortex Coronagraph at the W. M. Keck Observatory

Ruane, Garreth and Ngo, Henry and Mawet, Dimitri and Absil, Olivier and Choquet, Élodie and Cook, Therese and Gomez Gonzalez, Carlos A. and Huby, Elsa and Matthews, Keith and Meshkat, Tiffany and Reggiani, Maddalena and Serabyn, Eugene and Wallack, Nicole and Xuan, W. Jerry (2019) Reference Star Differential Imaging of Close-in Companions and Circumstellar Disks with the NIRC2 Vortex Coronagraph at the W. M. Keck Observatory. Astronomical Journal, 157 (3). Art. No. 118. ISSN 1538-3881. doi:10.3847/1538-3881/aafee2.

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Reference star differential imaging (RDI) is a powerful strategy for high-contrast imaging. Using example observations taken with the vortex coronagraph mode of Keck/NIRC2 in L' band, we demonstrate that RDI provides improved sensitivity to point sources at small angular separations compared to angular differential imaging (ADI). Applying RDI to images of the low-mass stellar companions HIP 79124 C (192 mas separation, ΔL' = 4.01) and HIP 78233 B (141 mas separation, ΔL' = 4.78), the latter a first imaging detection, increases the significance of their detections by up to a factor of 5 with respect to ADI. We compare methods for reference frame selection and find that pre-selection of frames improves detection significance of point sources by up to a factor of 3. In addition, we use observations of the circumstellar disks around MWC 758 and 2MASS J16042165−2130284 to show that RDI allows for accurate mapping of scattered light distributions without self-subtraction artifacts.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Ruane, Garreth0000-0003-4769-1665
Ngo, Henry0000-0001-5172-4859
Mawet, Dimitri0000-0002-8895-4735
Absil, Olivier0000-0002-4006-6237
Choquet, Élodie0000-0002-9173-0740
Gomez Gonzalez, Carlos A.0000-0003-2050-1710
Meshkat, Tiffany0000-0001-6126-2467
Reggiani, Maddalena0000-0003-2911-0898
Wallack, Nicole0000-0003-0354-0187
Xuan, W. Jerry0000-0002-6618-1137
Additional Information:© 2019 The American Astronomical Society. Received 2018 November 28; revised 2019 January 13; accepted 2019 January 14; published 2019 February 14. G.R. is supported by an NSF Astronomy and Astrophysics Postdoctoral Fellowship under award AST-1602444. 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 (NASA). The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. Facility: Keck:II (NIRC2). - Software: VIP (Gomez Gonzalez et al. 2017), QACITS (Huby et al. 2015, 2017), Astropy (The Astropy Collaboration et al. 2018), orbitize (Blunt et al. 2018).
Group:Infrared Processing and Analysis Center (IPAC), Astronomy Department
Funding AgencyGrant Number
NSF Astronomy and Astrophysics FellowshipAST-1602444
W. M. Keck FoundationUNSPECIFIED
Issue or Number:3
Record Number:CaltechAUTHORS:20190214-105330131
Persistent URL:
Official Citation:Garreth Ruane et al 2019 AJ 157 118
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:92934
Deposited By: Tony Diaz
Deposited On:14 Feb 2019 19:41
Last Modified:16 Nov 2021 16:54

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