The Properties of the 500 K Dwarf UGPS J072227.51-054031.2, and a Study of the Far-Red Flux of Cold Brown Dwarfs
S. K. Leggett, D. Saumon, M. S. Marley, K. Lodders, J. Canty, P. Lucas, R. L. Smart, C. G. Tinney, D. Homeier, F. Allard, Ben Burningham, A. Day-Jones, B. Fegle… 展开作者
S. K. Leggett, D. Saumon, M. S. Marley, K. Lodders, J. Canty, P. Lucas, R. L. Smart, C. G. Tinney, D. Homeier, F. Allard, Ben Burningham, A. Day-Jones, B. Fegley, Miki Ishii, H. R. A. Jones, F. Marocco, D. J. Pinfield, M. Tamura
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46 pages, 5 Tables, 15 Figures; accepted for publication in ApJ, January 13 2012
We present i and z photometry for 25 T dwarfs and one L dwarf. Combined with published photometry, the data show that the i - z, z - Y and z - J colors of T dwarfs are very red, and continue to increase through to the late-type T dwarfs, with a hint of a saturation for the latest types with T_eff ~ 600 K. We present new 0.7-1.0 um and 2.8-4.2 um spectra for the very late-type T dwarf UGPS J072227.51-054031.2, as well as improved astrometry for this dwarf. Examination of the spectral energy distribution using the new and published data, with Saumon & Marley models, shows that the dwarf has T_eff = 505 +/- 10 K, a mass of 3-11 M_Jupiter and an age between 60 Myr and 1 Gyr. This young age is consistent with the thin disk kinematics of the dwarf. The mass range overlaps with that usually considered to be planetary, despite this being an unbound object discovered in the field near the Sun. This apparently young rapid rotator is also undergoing vigorous atmospheric mixing, as determined by the IRAC and WISE-2 4.5 um photometry and the Saumon & Marley models. The optical spectrum for this 500 K object shows clearly detected lines of the neutral alkalis Cs and Rb, which are emitted from deep atmospheric layers with temperatures of 900-1200 K.
\textit{Gaia} EDR3 confirms a red dwarf companion of the nearby F1 star HD 105452 and reveals a new brown dwarf companion of the M4.5 dwarf SCR J1214-2345
The Sonora Substellar Atmosphere Models VI. Red Diamondback: Extending Diamondback with SPHINX for Brown Dwarf Early Evolution
University of California, Santa Cruz（加州大学圣克鲁兹分校）；Goddard Space Flight Center（戈达德太空飞行中心）；Arizona State University（亚利桑那州立大学）；University of Texas at Austin（得克萨斯大学奥斯汀分校）；University of Arizona（亚利桑那大学）；Boston University（波士顿大学）
Phase-resolved Hubble Space Telescope WFC3 Spectroscopy of Weakly-Irradiated Brown Dwarf GD 1400 and Energy Redistribution-Irradiation Trends in Six WD$-$BD Binaries
Time-resolved Hubble Space Telescope Wide Field Camera 3 Spectrophotometry Reveals Inefficient Day-to-Night Heat Redistribution in the Highly Irradiated Brown Dwarf SDSS 1557B
The Pan-STARRS1 Proper-motion Survey for Young Brown Dwarfs in Nearby Star-forming Regions. I. Taurus Discoveries and a Reddening-free Classification Method for Ultracool Dwarfs
我们正在进行一项基于泛星1 3 $π$巡天的金牛座-御夫座分子云中年轻棕矮星的自行巡天。我们的搜索使用多波段测光和天体测量来选择候选者，并且比以前的搜索更宽（370度$^{2}$）和更深（$\approx$ 3 M $_{\rm Jup}$）。我们在这里介绍我们的搜索方法和光谱跟踪我们的高优先级候选人。由于消光使光谱分类复杂化，我们开发了一种新的方法，使用低分辨率（$R \approx 100$）近红外光谱来量化M中期至L晚期超冷矮星（金牛座的$\approx 100-3$ M $_{\rm Jup}$）的无红化光谱类型、消光和重力分类。我们已经发现了金牛座的25个低重力（VL-G）和前11个中等重力（INT-G）亚恒星（M6-L1）成员，这是迄今为止金牛座褐矮星数量增加最多的一次。我们还发现了一个新的昴星团成员和13个英仙座OB 2星协的新成员，包括一个候选的非常宽的分离（58 kAU）的二进制。我们对所有以前已知的金牛座褐矮星的光谱类型和灭绝进行了均匀的重新分类。总之，我们的发现使金牛座的亚恒星数量增加了$\approx 40\%$，并增加了三个L型成员（$\approx 5-10$ M $_{\rm Jup}$）。最值得注意的是，我们的发现揭示了金牛座中一个更古老（$>$ 1000万年）的低质量人口，与最近对高质量恒星成员的研究一致。质量函数似乎在年轻和年老的金牛座群体之间存…
Two Exciting High-redshift Galaxy Candidates Turn Out to Be Two Exciting Ultra-cool Brown Dwarfs
University of Ljubljana（卢布尔雅那大学）；University of California Davis（加州大学戴维斯分校）；NRC Herzberg（赫茨堡国家研究委员会）；Dunlap Institute for Astronomy and Astrophysics（邓普天文学与天体物理研究所）；Institut Trottier de recherche sur les exoplanètes and Département de Physique, Université de Montréal（蒙特利尔大学特鲁瓦耶系外行星研究所及物理系）；Scuola Normale Superiore（比萨高等师范学院）；University of Arizona（亚利桑那大学）
