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Published February 20, 2022 | Accepted Version + Published
Journal Article Open

CWISE J014611.20–050850.0AB: The Widest Known Brown Dwarf Binary in the Field

Abstract

While stars are often found in binary systems, brown dwarf binaries are much rarer. Brown dwarf–brown dwarf pairs are typically difficult to resolve because they often have very small separations. Using brown dwarfs discovered with data from the Wide-field Infrared Survey Explorer (WISE) via the Backyard Worlds: Planet 9 citizen science project, we inspected other, higher-resolution, sky surveys for overlooked cold companions. During this process, we discovered the brown dwarf binary system CWISE J0146−0508AB, which we find has a very small chance alignment probability based on the similar proper motions of the components of the system. Using follow-up near-infrared spectroscopy with Keck/NIRES, we determined component spectral types of L4 and L8 (blue), making CWISE J0146−0508AB one of only a few benchmark systems with a blue L dwarf. At an estimated distance of ∼40 pc, CWISE J0146−0508AB has a projected separation of ∼129 au, making it the widest-separation brown dwarf pair found to date. We find that such a wide separation for a brown dwarf binary may imply formation in a low-density star-forming region.

Additional Information

© 2022. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Received 2022 January 3; revised 2022 January 31; accepted 2022 February 3; published 2022 February 17. The Backyard Worlds: Planet 9 team would like to thank the many Zooniverse volunteers who have participated in this project. We would also like to thank the Zooniverse web development team for their work creating and maintaining the Zooniverse platform and the Project Builder tools. This research was supported by NASA grant 2017-ADAP17-0067. This material is based upon work supported by the National Science Foundation under grant Nos. 2007068, 2009136, and 2009177. Some of 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. This publication makes use of data products from the Wide-field Infrared Survey Explorer, which is a joint project of the University of California, Los Angeles, and the Jet Propulsion Laboratory/California Institute of Technology, and NEOWISE, which is a project of the Jet Propulsion Laboratory/California Institute of Technology. WISE and NEOWISE are funded by the National Aeronautics and Space Administration. 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. The Pan-STARRS1 Surveys (PS1) and the PS1 public science archive have been made possible through contributions by the Institute for Astronomy, the University of Hawaii, the Pan-STARRS1 Project Office, the Max Planck Society and its participating institutes, the Max Planck Institute for Astronomy, Heidelberg, and the Max Planck Institute for Extraterrestrial Physics, Garching, The Johns Hopkins University, Durham University, the University of Edinburgh, the Queen's University Belfast, the Harvard-Smithsonian Center for Astrophysics, the Las Cumbres Observatory Global Telescope Network Incorporated, the National Central University of Taiwan, the Space Telescope Science Institute, the National Aeronautics and Space Administration under grant No. NNX08AR22G issued through the Planetary Science Division of the NASA Science Mission Directorate, National Science Foundation grant No. AST-1238877, the University of Maryland, Eotvos Lorand University (ELTE), Los Alamos National Laboratory, and the Gordon and Betty Moore Foundation. Facility: Keck (NIRES). - Software: SpeXTool (Cushing et al. 2010); SPLAT (Burgasser & Splat Development Team 2017); CoMover (Gagné et al. 2021).

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Published - Softich_2022_ApJL_926_L12.pdf

Accepted Version - 2202.02315.pdf

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Additional details

Created:
August 22, 2023
Modified:
October 23, 2023