The Diversity of Cold Worlds: A Blended-light Binary Straddling the T/Y Transition in Brown Dwarfs
Abstract We present the first brown dwarf spectral binary characterized with JWST: WISE J014656.66+423410.0, the coldest blended-light brown dwarf binary straddling the T/Y transition. We obtained a moderate resolution ( R ∼ 2700) G395H spectrum of this unresolved binary with JWST/NIRSpec and we fit it to late T and Y dwarf spectra from JWST/NIRSpec, and model spectra of comparable temperatures, both as individual spectra and pairs mimicking an unresolved binary system. We find that this tightly separated binary is likely composed of two unequal-brightness sources with a magnitude difference of 0.50 ± 0.08 mag in IRAC [4.5] and a secondary 1.01 ± 0.13 mag redder than the primary in [3.6]–[4.5]. Despite the large color difference between the best-fit primary and secondary, their temperature difference is only 92 ± 23 K, a feature reminiscing of the L/T transition. Carbon disequilibrium chemistry strongly shapes the mid-infrared spectra of these sources, as a complex function of the metallicity and surface gravity. While a larger library of JWST/NIRSpec spectra is needed to conclusively examine the peculiarities of blended-light sources, this spectral binary is a crucial pathfinder to both understand the spectral features of planetary-mass atmospheres and detect binarity in unresolved, moderate-resolution spectra of the coldest brown dwarfs.
Authors
- Adam C. Schneider (ORCID: https://orcid.org/0000-0002-6294-5937)
- Melanie J. Rowland (ORCID: https://orcid.org/0000-0003-4225-6314)
- Jacqueline K. Faherty (ORCID: https://orcid.org/0000-0001-6251-0573)
- Christopher R. Gelino (ORCID: https://orcid.org/0000-0001-5072-4574)
- Johanna M. Vos (ORCID: https://orcid.org/0000-0003-0489-1528)
- Dan Caselden (ORCID: https://orcid.org/0000-0001-7896-5791)
- Ehsan Gharib-Nezhad (ORCID: https://orcid.org/0000-0002-4088-7262)
- Charles Beichman (ORCID: https://orcid.org/0000-0002-5627-5471)
- Niall Whiteford (ORCID: https://orcid.org/0000-0001-8818-1544)
- J. Davy Kirkpatrick (ORCID: https://orcid.org/0000-0003-4269-260X)
- Peter Eisenhardt
- Federico Marocco (ORCID: https://orcid.org/0000-0001-7519-1700)
- Klara Matuszewska
- Jonathan Gagné (ORCID: https://orcid.org/0000-0002-2592-9612)
- Ben Burningham (ORCID: https://orcid.org/0000-0003-4600-5627)
- Genaro Suárez (ORCID: https://orcid.org/0000-0002-2011-4924)
- Austin Rothermich (ORCID: https://orcid.org/0000-0003-4083-9962)
- Caroline Morley (ORCID: https://orcid.org/0000-0002-4404-0456)
- Aaron Meisner (ORCID: https://orcid.org/0000-0002-1125-7384)
- Rocio Kiman (ORCID: https://orcid.org/0000-0003-2102-3159)
- Sherelyn Alejandro Merchan (ORCID: https://orcid.org/0000-0003-0548-0093)
- Eileen C. Gonzales (ORCID: https://orcid.org/0000-0003-4636-6676)
- Brianna Lacy (ORCID: https://orcid.org/0000-0002-9420-4455)
- Daniella C. Bardalez Gagliuffi (ORCID: https://orcid.org/0000-0001-8170-7072)
- Marc J. Kuchner (ORCID: https://orcid.org/0000-0002-2387-5489)
Publication Details
- Journal
- The Astrophysical Journal
- Published
- 2025-04-28
- DOI
- https://doi.org/10.3847/1538-4357/adb61e
- Citations
- 3
- Primary Topic
- Stellar, planetary, and galactic studies
- Type
- article
- Field-Weighted Citation Impact
- 3.46