The JWST Weather Report from the Nearest Brown Dwarfs. III. Heterogeneous Clouds and Thermochemical Instabilities as Possible Drivers of WISE 1049AB's Spectroscopic Variability
Abstract
We present a new analysis of the spectroscopic variability of WISE J104915.57−531906.1AB (WISE 1049AB, L7.5+T0.5), observed using the NIRSpec instrument on board the James Webb Space Telescope (GO 2965; PI: Biller). We explore the variability of the dominant molecular bands present in their 0.6–5.3 μ m spectra (H 2 O, CH 4 , and CO), finding that the B component exhibits a higher maximum deviation than the A component in all the wavelength ranges tested. The light curves reveal wavelength-dependent (atmospheric depth) and possibly chemistry-dependent variability. In particular, for the A component, the variability in the light curves at the wavelengths traced by the CH 4 and CO molecular absorption features is higher than that for of H 2 O, even when both trace similar pressure levels. We conclude that clouds alone are unlikely to explain the increased variability of CO and CH 4 with respect to H 2 O, suggesting that an additional physical mechanism is needed to explain the observed variability. This mechanism is probably due to thermochemical instabilities. Finally, we provide visual representations of the 3D atmospheric maps reconstructed for both components using the molecular band contributions at different pressure levels and the fits of planetary-scale waves.
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BibTeX
@article{oliverosgomez2026jwst,
title = {{The JWST Weather Report from the Nearest Brown Dwarfs. III. Heterogeneous Clouds and Thermochemical Instabilities as Possible Drivers of WISE 1049AB's Spectroscopic Variability}},
author = {Natalia Oliveros-Gomez and Elena Manjavacas and Theodora Karalidi and Myrla Phillippe and Beatriz Campos Estrada and Beth Biller and Johanna M. Vos and Jacqueline Faherty and Xueqing Chen and Trent J. Dupuy and Thomas Henning and Allison M. Mccarthy and Philip S. Muirhead and Elspeth K. H. Lee and Pascal Tremblin and Jasmine Ramirez and Genaro Suarez and Ben J. Sutlieff and Xianyu Tan and Nicolas Crouzet},
journal = {The Astrophysical Journal},
year = {2026},
month = nov,
doi = {10.3847/1538-4357/ae21d9},
url = {https://hal.science/hal-05851614v1},
note = {CC BY},
}
RIS
TY - JOUR
TI - The JWST Weather Report from the Nearest Brown Dwarfs. III. Heterogeneous Clouds and Thermochemical Instabilities as Possible Drivers of WISE 1049AB's Spectroscopic Variability
AU - Natalia Oliveros-Gomez
AU - Elena Manjavacas
AU - Theodora Karalidi
AU - Myrla Phillippe
AU - Beatriz Campos Estrada
AU - Beth Biller
AU - Johanna M. Vos
AU - Jacqueline Faherty
AU - Xueqing Chen
AU - Trent J. Dupuy
AU - Thomas Henning
AU - Allison M. Mccarthy
AU - Philip S. Muirhead
AU - Elspeth K. H. Lee
AU - Pascal Tremblin
AU - Jasmine Ramirez
AU - Genaro Suarez
AU - Ben J. Sutlieff
AU - Xianyu Tan
AU - Nicolas Crouzet
PY - 2026
DA - 2026/11/04
JO - The Astrophysical Journal
DO - 10.3847/1538-4357/ae21d9
UR - https://hal.science/hal-05851614v1
AB - We present a new analysis of the spectroscopic variability of WISE J104915.57−531906.1AB (WISE 1049AB, L7.5+T0.5), observed using the NIRSpec instrument on board the James Webb Space Telescope (GO 2965; PI: Biller). We explore the variability of the dominant molecular bands present in their 0.6–5.3 μ m spectra (H 2 O, CH 4 , and CO), finding that the B component exhibits a higher maximum deviation than the A component in all the wavelength ranges tested. The light curves reveal wavelength-dependent (atmospheric depth) and possibly chemistry-dependent variability. In particular, for the A component, the variability in the light curves at the wavelengths traced by the CH 4 and CO molecular absorption features is higher than that for of H 2 O, even when both trace similar pressure levels. We conclude that clouds alone are unlikely to explain the increased variability of CO and CH 4 with respect to H 2 O, suggesting that an additional physical mechanism is needed to explain the observed variability. This mechanism is probably due to thermochemical instabilities. Finally, we provide visual representations of the 3D atmospheric maps reconstructed for both components using the molecular band contributions at different pressure levels and the fits of planetary-scale waves.
SN - 0004-637X
SN - 1538-4357
ER -