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Published July 2018 | public
Journal Article

A Secure W2 Detection of WD 0806-661B from CatWISE


The WD 0806-661 system consists of a DQ white dwarf primary at 19.26 pc (Gaia Collaboration et al. 2018) and an extremely cold common proper motion companion at 130'' separation (WD 0806-661B; Luhman et al. 2011). Given its absolute magnitude at Spitzer [4.5], the cold companion is presumed to be either a Y type brown dwarf or giant planet. At a projected physical separation of ~2500 au, WD 0806-661B represents the widest known definitively planetary-mass companion, and may provide important insights into the processes of star and planet formation. Unlike most Y dwarfs, WD 0806-661B has lacked a secure detection at 4.6 μm in the Wide-field Infrared Survey Explorer (WISE; Wright et al. 2010) W2 channel. WD 0806-661B was reported as a low-significance detection in the WISE All-Sky Source Catalog (Cutri et al. 2012), with W2 = 17.68 ± 0.41 (J080715.32-661851.6, w2snr = 2.5). No detection of a WD 0806-661B counterpart is reported in the AllWISE Source Catalog, although the AllWISE Reject Table contains a low-significance positional match (J080715.34-661852.1) with W2 = 17.85 ± 0.41 (Cutri et al. 2013). Both the All-Sky and AllWISE Reject best-fit W2 magnitudes, if taken at face value, would make WD 0806-661B a very blue outlier among Y dwarfs in [4.5]−W2 color, given that the W2 and [4.5] magnitudes of known Y dwarfs generally agree to within ~0.1 mag.

Additional Information

© 2018 The American Astronomical Society. Received 2018 August 1; Accepted 2018 August 2; Published 2018 August 7. This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. CatWISE is funded by NASA under Proposal No. 16-ADAP16-0077 issued through the Astrophysics Data Analysis Program, and uses data from the NASA-funded WISE and NEOWISE projects. This work has also been supported by Hubble Fellowship HST-HF2-51415.001-A, NASA ADAP grant NNH17AE75I, and has benefited from the Y Dwarf Compendium maintained by Michael Cushing at https://sites.google.com/view/ydwarfcompendium.

Additional details

August 19, 2023
October 18, 2023