# Tracing the Top-of-the-atmosphere and Vertical Cloud Structure of a fast-rotating late T-dwarf

**Authors:** Elena Manjavacas, Theodora Karalidi, Xianyu Tan, Johanna M. Vos, Ben W. P. Lew, Beth A. Biller, Natalia Oliveros-Gomez  
**arXiv:** [2206.07566](https://arxiv.org/abs/2206.07566)  
**Date:** 2022-06-15  
**Summary page:** https://www.summarizepaper.com/en/paper/2206.07566v1/

## Key points

- Study focuses on atmospheric cloud structures of late-T brown dwarfs
- Monitored 2MASSJ00501994-332240, a T7.0 rapidly rotating field brown dwarf with low-level photometric variability
- Used MOSFIRE installed at the Keck I telescope to measure near-infrared spectro-photometric variability
- Detected peak-to-peak amplitudes of fluctuations in different light curves:
- 1.48±0.75% in J-band photometric light curve
- 0.62±0.18% in J-band spectro-photometric light curve
- 1.26±0.93% in H-band light curve
- 5.33±2.02% in CH_4–H_2O band light curve
- Bayesian Information Criterion did not detect significant variability due to detection limitations from MOSFIRE sensitivity; therefore only tentative low-level variability could be claimed for 2M0050–3322 under best-case scenarios.
- Amplitudes of peak-to-peak fluctuations measured for 2MASSJ00501994–332240 agree with General Circulation Models' predictions for a T7.0 brown dwarf for an edge-on object's variability amplitude prediction.
- Radiative-transfer models predict that Na_2S and KCl clouds condense at pressures lower than that traced by CH_4–H_2O bands which might explain higher peak-to-peak fluctuations measured for this light curve.
- Authors provide visual recreation of maps provided by General Circulation Models and vertical structure provided by radiative transfer models comparing their results with other late T brown dwarfs and found several differences and commonalities between them such as only two other late T dwarfs have been monitored for spectro photometric variability: 2MASS J22282889 – 431026 (T6 .5) and Ross 458c (T7 .5).

## Summary

This study focuses on the atmospheric cloud structures of late-T brown dwarfs, which share temperatures with cold, directly-imaged exoplanets. The authors monitored 2MASSJ00501994-332240, a T7.0 rapidly rotating field brown dwarf that showed low-level photometric variability in data obtained with the Spitzer Space Telescope. They used MOSFIRE installed at the Keck I telescope to constrain its near-infrared spectro-photometric variability and measured fluctuations with peak-to-peak amplitudes of 1.48±0.75% in the J-band photometric light curve, 0.62±0.18% in the J-band spectro-photometric light curve, 1.26±0.93% in the H-band light curve, and 5.33±2.02% in the CH_4–H_2O band light curve. However, despite these measurements, the Bayesian Information Criterion did not detect significant variability in any of the light curves due to detection limitations from MOSFIRE sensitivity; therefore they could only claim tentative low–level variability for 2M0050–3322 under best–case scenarios. The amplitudes of peak–to–peak fluctuations measured for 2MASSJ00501994–332240 agree with General Circulation Models' predictions for a T7.0 brown dwarf for an edge–on object's variability amplitude prediction. Radiative–transfer models predict that Na_2S and KCl clouds condense at pressures lower than that traced by CH_4–H_2O bands which might explain higher peak–to–peak fluctuations measured for this light curve. The authors also provide a visual recreation of maps provided by General Circulation Models and vertical structure provided by radiative transfer models comparing their results with other late T brown dwarfs and found several differences and commonalities between them such as only two other late T dwarfs have been monitored for spectro photometric variability: 2MASS J22282889 – 431026 (T6 .5) and Ross 458c (T7 .5).