• DOI:10.3847/2041-8213/ac0437
• Corpus ID: 235651911

The Enigmatic Brown Dwarf WISEA J153429.75-104303.3 (a.k.a. “The Accident”)

@article{Kirkpatrick2021TheEB,
  title={The Enigmatic Brown Dwarf WISEA J153429.75-104303.3 (a.k.a. “The Accident”)},
  author={J. Davy Kirkpatrick and Federico Marocco and Dan Caselden and Aaron M. Meisner and Jacqueline K. Faherty and Adam C. Schneider and Marc J. Kuchner and Sarah L. Casewell and Christopher Ryan Gelino and Michael C. Cushing and Peter R. Eisenhardt and E. L. Wright and Steven D. Schurr},
  journal={The Astrophysical Journal Letters},
  year={2021},
  volume={915}
}

• J. Kirkpatrick, F. Marocco, +10 authors S. Schurr
• Published 25 June 2021
• Physics, Geology
• The Astrophysical Journal Letters

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 16.3−1.2+1.4 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.