Enigmatic Brown Dwarf WISEA J153429.75-104303.3 (a.k.a. "The Accident")
Abstract
Continued follow-up of WISEA J153429.75−104303.3, announced in Meisner et al., has proven it to have an unusual set of properties. New imaging data from Keck/MOSFIRE and HST/WFC3 shows that this object is one of the few faint proper motion sources known with J − ch2 >8 mag, indicating a very cold temperature consistent with the latest known Y dwarfs. Despite this, it has W1−W2 and ch1−ch2 colors ~1.6 mag bluer than a typical Y dwarf. A new trigonometric parallax measurement from a combination of WISE, Spitzer, and HST astrometry confirms a nearby distance of 16.3^(+1.4)_(-1.2) pc and a large transverse velocity of 207.4 ± 15.9 km s⁻¹. The absolute J, W2, and ch2 magnitudes are in line with the coldest known Y dwarfs, despite the highly discrepant W1−W2 and ch1−ch2 colors. We explore possible reasons for the unique traits of this object and conclude that it is most likely an old, metal-poor brown dwarf and possibly the first Y subdwarf. Given that the object has an HST F110W magnitude of 24.7 mag, broadband spectroscopy and photometry from JWST are the best options for testing this hypothesis.
Additional Information
© 2021. The American Astronomical Society. Received 2021 May 10; revised 2021 May 18; accepted 2021 May 21; published 2021 June 30. This research is based on observations made under program 16243 with the NASA/ESA Hubble Space Telescope obtained from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 526555. Some of the data presented here 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 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. This publication makes use of data products from WISE/NEOWISE, which is a joint project of UCLA and JPL/Caltech, funding by NASA. Portions of this research were carried out at JPL/Caltech under contract with NASA. J.K.F. thanks the Heising Simons Foundation for research support. Facilities: HST (WFC3) - , Keck:I (MOSFIRE) - , WISE - , NEOWISE - Software: WiseView (Caselden et al. 2018).Attached Files
Published - Kirkpatrick_2021_ApJL_915_L6.pdf
Accepted Version - 2106.13408.pdf
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Additional details
- Eprint ID
- 109888
- Resolver ID
- CaltechAUTHORS:20210716-220506187
- NAS 5-26555
- NASA
- W. M. Keck Foundation
- NASA/JPL/Caltech
- Heising-Simons Foundation
- Created
-
2021-07-16Created from EPrint's datestamp field
- Updated
-
2021-07-16Created from EPrint's last_modified field
- Caltech groups
- Infrared Processing and Analysis Center (IPAC)