We report the discovery of a photometric variability in the bright T2.5 brown dwarf SIMP J013656.5+093347. Continuous J-band photometry has been obtained for several hours on four different nights. The light curves show a periodic modulation with a period of ~2.4 hours, a peak-to-peak amplitude of ~50 mmag and significant night-to-night evolution. We suggest that the light curve modulation is due to the brown dwarf's rotation and that the longer term variations come from surface features evolution and/or differential rotation. We obtained complementary observations over a single night in the J and Ks bands; the object displays correlated photometric variability in both bands, albeit with smaller Ks-band amplitude. The ratio of the Ks and J variability amplitudes puts strong constraints on the physical mechanisms at play. Based on theoretical models of brown dwarf atmospheres, our results suggest that the atmosphere of SIMP0136 is comprised of both grain-free and colder (by ~100 K) grain-bearing cloudy regions. This discovery, and its interpretation, provide a natural explanation of the so-called J-band brightening.
The JWST weather report from the nearest brown dwarfs II: Consistent variability mechanisms over 7 months revealed by 1-14 $μ$m NIRSpec + MIRI monitoring of WISE 1049AB
The JWST weather report from the nearest brown dwarfs III: Heterogeneous clouds and Thermochemical instabilities as possible drivers of WISE 1049AB's spectroscopic variability
Johns Hopkins University（约翰斯·霍普金斯大学）；Space Telescope Science Institute（太空望远镜科学研究所）；University of Central Florida（中佛罗里达大学）；University of Edinburgh（爱丁堡大学）；Trinity College Dublin, The University of Dublin（都柏林三一学院，都柏林大学）；American Museum of Natural History（美国自然历史博物馆）；Boston University（波士顿大学）；University of Bern（伯尔尼大学）；The Graduate Center, City University of New York（纽约市立大学研究生中心）；Shanghai Jiao Tong University（上海交通大学）；Rijksuniversiteit Groningen（格罗宁根大学）
多普勒成像使用高色散光谱技术生成旋转物体的2D全球地图。当应用于褐矮星和太阳系外行星时，这种技术可以以前所未有的细节约束全球大气动力学和/或磁场对这些物体的影响。我提出了第一个定量评估的前景多普勒成像的亚恒星物体与现有的设施和未来的巨型地面望远镜。K波段的观测灵敏度最高，但H和L波段也可用于这些目的。为了评估目标的数量和可用性，我还提出了一个汇编的光度变化，旋转周期（P）和投影旋转速度（v sin i）的棕矮星和系外行星的所有测量。几个明亮的物体已经可以用现有的仪器进行多普勒成像。随着巨大的地面望远镜的发展，多普勒成像将成为可行的几十个棕矮星和少数最明亮的直接成像的太阳系外行星（如β Pic b）。目前对P、v sin i和变异性的测量对于许多天体来说是不完整的，并且样本强烈地偏向于早期类型的天体（< L5）。因此，测量晚型物体的这些量的调查将特别有助于扩大通过多普勒成像进行全球天气监测的候选样本。
The JWST weather report: Unravelling the atmospheric variability of isolated worlds using principal component analysis
Trinity College Dublin, The University of Dublin（都柏林三一学院，都柏林大学）；American Museum of Natural History（美国自然历史博物馆）；McGill University（麦吉尔大学）；University of Edinburgh（爱丁堡大学）；University of Hertfordshire（赫特福德大学）
Tempawral: A Time-Resolved Retrieval Framework for Variable Brown Dwarfs and Exoplanets
University of Hertfordshire（赫特福德大学）；University of Sheffield（谢菲尔德大学）；Université de Montréal（蒙特利尔大学）；National Astronomical Observatory of Japan（日本国立天文台）；SOKENDAI（综合研究大学院大学）；American Museum of Natural History（美国自然历史博物馆）；The Graduate Center City University of New York（纽约市立大学研究生中心）；Trinity College Dublin, The University of Dublin（都柏林三一学院，都柏林大学）
