We present the discovery of two brown dwarfs in the UKIRT Infrared Deep Sky Survey (UKIDSS) Deep Extragalactic Survey (DXS) Data Release 2. Both objects were selected photometrically from six square degrees in DXS for their blue J-K colour and the lack of optical counterparts in the Sloan Digital Sky Survey (SDSS) Stripe 82. Additional optical photometry provided by the Canada-France-Hawaii Telescope Legacy Survey (CFHT-LS) corroborated the possible substellarity of these candidates. Subsequent methane imaging of UDXS J221611.51+003308.1 and UDXS J221903.10+002418.2, has confirmed them as T7$\pm$1 and T6$\pm$1 dwarfs at photometric distances of 81 (52-118 pc) and 60 (44-87 pc; 2 sigma confidence level). A similar search in the second data release of the Ultra Deep Survey over a smaller area (0.77 square degree) and shallower depth didn't return any late-T dwarf candidate. The numbers of late-T dwarfs in our study are broadly in line with a declining mass function when considering the current area and depth of the DXS and UDS. These brown dwarfs are the first discovered in the VIMOS 4 field and among the few T dwarfs found in pencil-beam surveys. They are valuable to investigate the scale height of T dwarfs.
JADES: An Abundance of Ultra-Distant T- and Y-Dwarfs in Deep Extragalactic Data
University of Arizona（亚利桑那大学）；The Pennsylvania State University（宾夕法尼亚州立大学）；Lunar & Planetary Laboratory, University of Arizona（亚利桑那大学月球与行星实验室）；University of California, Santa Cruz（加州大学圣克鲁斯分校）；NASA Ames Research Center（美国宇航局艾姆斯研究中心）；University of Oxford（牛津大学）；University of Cambridge（剑桥大学）；University College London（伦敦大学学院）
我们从斯隆数字巡天（SDSS DR 7）的第七次数据发布中选择了棕矮星候选者，新的光度选择标准是基于著名的L和T矮星的参数化。然后我们用SDSS光谱确认了它们的状态。没有SDSS光谱的候选者在2微米全天巡天（2MASS）和UKIRT红外深空巡天（UKIDSS DR 4）的第四次数据发布中进行交叉匹配。在基于SDSS、2MASS和UKIDSS的颜色的帮助下，我们能够估计候选者的光谱类型。我们获得可靠的自行使用直接从调查数据库下载的位置和历元信息。
White Dwarfs with Infrared Excess from LAMOST Data Release 11
College of Physics, Guizhou University（贵州大学物理学院）；Gemini Observatory/NSF’s NOIRLab（吉米天文台/美国国家科学基金会NOIRLab）；Departament de Física, Universitat Politècnica de Catalunya（加泰罗尼亚理工大学物理系）；Institut d’Estudis Espacials de Catalunya（加泰罗尼亚空间研究所）
