The Diversity of Cold Worlds: a blended-light binary straddling the T/Y transition in brown dwarfs
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| Main Authors: | , , , , , , , , , , , , , , , , , , , , , , , , |
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| Format: | Preprint |
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2025
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| author | Gagliuffi, Daniella C. Bardalez Faherty, Jacqueline K. Suarez, Genaro Merchan, Sherelyn Alejandro Lacy, Brianna Burningham, Ben Matuszewska, Klara Kiman, Rocio Vos, Johanna M. Rothermich, Austin Gagne, Jonathan Morley, Caroline Rowland, Melanie J. Caselden, Dan Meisner, Aaron Schneider, Adam C. Kuchner, Marc J. Beichman, Charles A. Eisenhardt, Peter R. Gelino, Christopher R. Gharib-Nezhad, Ehsan Gonzales, Eileen C. Marocco, Federico Whiteford, Niall Kirkpatrick, J. Davy |
| author_facet | Gagliuffi, Daniella C. Bardalez Faherty, Jacqueline K. Suarez, Genaro Merchan, Sherelyn Alejandro Lacy, Brianna Burningham, Ben Matuszewska, Klara Kiman, Rocio Vos, Johanna M. Rothermich, Austin Gagne, Jonathan Morley, Caroline Rowland, Melanie J. Caselden, Dan Meisner, Aaron Schneider, Adam C. Kuchner, Marc J. Beichman, Charles A. Eisenhardt, Peter R. Gelino, Christopher R. Gharib-Nezhad, Ehsan Gonzales, Eileen C. Marocco, Federico Whiteford, Niall Kirkpatrick, J. Davy |
| contents | 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$\sim$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 $0.50\pm0.08$ mag in IRAC [4.5] and a secondary $1.01\pm0.13$ 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 $92\pm23$\,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 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. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2503_02025 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | The Diversity of Cold Worlds: a blended-light binary straddling the T/Y transition in brown dwarfs Gagliuffi, Daniella C. Bardalez Faherty, Jacqueline K. Suarez, Genaro Merchan, Sherelyn Alejandro Lacy, Brianna Burningham, Ben Matuszewska, Klara Kiman, Rocio Vos, Johanna M. Rothermich, Austin Gagne, Jonathan Morley, Caroline Rowland, Melanie J. Caselden, Dan Meisner, Aaron Schneider, Adam C. Kuchner, Marc J. Beichman, Charles A. Eisenhardt, Peter R. Gelino, Christopher R. Gharib-Nezhad, Ehsan Gonzales, Eileen C. Marocco, Federico Whiteford, Niall Kirkpatrick, J. Davy Solar and Stellar Astrophysics Earth and Planetary Astrophysics 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$\sim$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 $0.50\pm0.08$ mag in IRAC [4.5] and a secondary $1.01\pm0.13$ 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 $92\pm23$\,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 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. |
| title | The Diversity of Cold Worlds: a blended-light binary straddling the T/Y transition in brown dwarfs |
| topic | Solar and Stellar Astrophysics Earth and Planetary Astrophysics |
| url | https://arxiv.org/abs/2503.02025 |