LHS 2803 B：一个非常宽的中T矮星伴星，是一个老M矮星的伴星，从Pan-STARRS1中识别出来。
LHS 2803B: A very wide mid-T dwarf companion to an old M dwarf identified from Pan-STARRS1
摘要：
我们报告发现了一个宽的（约400 AU的投影分离），共同的自行伴星附近的M矮星LHS 2803（PSO J207.0300-13.7422）。这个物体是在我们使用Pan-STARRS 1和2 MASS数据对当地T矮人人口进行普查时发现的。使用IRTF/SpeX近红外光谱，我们将次级分类为光谱类型T5.5。夏威夷大学的2.2m/SNIFS光谱分析表明，该恒星的光谱类型为M4.5，具有近似太阳的金属丰度，没有可测量的H_α辐射。我们利用这种缺乏活动的情况为3.5 Gyr系统设定了一个较低的年龄限制。通过与褐矮星和附近恒星的随机排列进行比较，我们得出结论，这两个物体不太可能是一个偶然的协会。主星的测光距离为21秒差距，其自行意味着薄盘运动学。根据这些运动学和它的金属丰度，我们为10 Gyr系统设定了年龄上限。演化模型的计算结果表明，次级星系的质量为72^+4_-7 M_Jup，温度为1120+-80 K，log g=5.4+-0.1 dex。模型大气拟合近红外光谱给出了类似的物理参数为1100 K和log g=5.0。
英文摘要：
We report the discovery of a wide (approximately 400 AU projected separation), common proper motion companion to the nearby M dwarf LHS 2803 (PSO J207.0300-13.7422). This object was discovered during our census of the local T dwarf population using Pan-STARRS1 and 2MASS data. Using IRTF/SpeX near-infrared spectroscopy, we classify the secondary to be spectral type T5.5. University of Hawai`i 2.2m/SNIFS optical spectroscopy indicates the primary has a spectral type of M4.5, with approximately solar metallicity and no measurable H_alpha emission. We use this lack of activity to set a lower age limit for the system of 3.5 Gyr. Using a comparison with chance alignments of brown dwarfs and nearby stars, we conclude that the two objects are unlikely to be a chance association. The primary's photometric distance of 21 pc and its proper motion implies thin disk kinematics. Based on these kinematics and its metallicity, we set an upper age limit for the system of 10 Gyr. Evolutionary model calculations suggest the secondary has a mass of 72^+4_-7 M_Jup, temperature of 1120+-80 K, and log g=5.4+-0.1 dex. Model atmosphere fitting to the near-IR spectrum gives similar physical parameters of 1100 K and log g=5.0.
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