The determination of the fundamental properties (mass, separation, age, gravity and atmospheric properties) of brown dwarf companions allows us to infer crucial informations on their formation and evolution mechanisms. Spectroscopy of substellar companions is available to date only for a limited number of objects (and mostly at very low resolution, R<50) because of technical limitations, i.e., contrast and angular resolution. We present medium resolution (R=350), coronagraphic long-slit spectroscopic observations with SPHERE of two substellar companions, HD 1160 B and HD 19467 B. We found that HD 1160 B has a peculiar spectrum that cannot be fitted by spectra in current spectral libraries. A good fit is possible only considering separately the Y+J and the H spectral band. The spectral type is between M5 and M7. We also estimated a T_eff of 2800-2900 K and a log(g) of 3.5-4.0 dex. The low surface gravity seems to favour young age (10-20 Myr) and low mass (~20 M Jup ) for this object. HD 19467 B is instead a fully evolved object with a T_eff of ~1000 K and log g of ~5.0 dex. Its spectral type is T6+/-1.

中文翻译：

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使用 IRDIS 长缝光谱表征褐矮星伴星：HD 1160 B 和 HD 19467 B

确定褐矮星伴星的基本特性（质量、分离度、年龄、重力和大气特性）使我们能够推断出有关它们的形成和演化机制的关键信息。由于技术限制，即对比度和角分辨率，迄今为止，只能对有限数量的物体（并且大多数分辨率非常低，R<50）进行亚星伴星的光谱分析。我们提出了中等分辨率 (R=350) 的日冕长缝光谱观测和两个亚星伴星 HD 1160 B 和 HD 19467 B 的 SPHERE。我们发现 HD 1160 B 有一个特殊的光谱，无法通过当前光谱中的光谱拟合图书馆。只有分别考虑 Y+J 和 H 光谱带才能实现良好的拟合。光谱类型介于 M5 和 M7 之间。我们还估计了 2800-2900 K 的 T_eff 和 3.5-4.0 dex 的 log(g)。低表面重力似乎有利于这个物体的年轻（10-20 Myr）和低质量（~20 M Jup）。HD 19467 B 是一个完全进化的物体，其 T_eff 为 ~1000 K，log g 为 ~5.0 dex。它的光谱类型是T6+/-1。