The 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 ${16.3}_{-1.2}^{+1.4}$ 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.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- July 2021
- DOI:
- 10.3847/2041-8213/ac0437
- arXiv:
- arXiv:2106.13408
- Bibcode:
- 2021ApJ...915L...6K
- Keywords:
-
- Stellar types;
- T dwarfs;
- Y dwarfs;
- Proper motions;
- Metallicity;
- 1634;
- 1679;
- 1827;
- 1295;
- 1031;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- 8 pages, 4 figures, accepted for publication in The Astrophysical Journal Letters