Hokupa’a-Gemini Discovery of Two Ultracool Companions to the Young Star HD 130948
Hokupa’a-Gemini Discovery of Two Ultracool Companions to the Young Star HD 130948
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Hokupa’a-双子座发现年轻恒星的两个超酷伴侣 HD 130948
DOI：
10.1086/339999
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发表时间：
2002
期刊：
影响因子：
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通讯作者：
R. Neuhäuser
中科院分区：
文献类型：
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作者：
D. Potter;E. L. Martín;M. Cushing;P. Baudoz;W. Brandner;W. Brandner;O. Guyon;R. Neuhäuser
我们报告使用安装在双子座北 8 m 望远镜上的 Hokupa'a 自适应光学 (AO) 仪器发现了附近 (d ~ 17.9 pc) 年轻 G2 V 星 HD 130948 (HR 5534, HIP 72567) 的两颗微弱超冷伴星。从 7 个月的基线来看，这两个天体都具有与主恒星相同的共同自行，并且具有与早期 L 分类一致的近红外光度颜色。使用 Keck II 望远镜上的 NIRSPEC AO 仪器拍摄的近红外光谱揭示了 K I 线、FeH 和 H2O 带头。根据这些光谱，我们确定两个物体的光谱类型均为 dL2，并且具有两个光谱子类的不确定性。与理论模型相比，新伴星在赫罗图上的位置与根据 X 射线活动、锂丰度和快速自转估计的主星的年轻年龄（<0.8 Gyr）一致。 HD 130948B和C可能构成一对年轻的收缩褐矮星，轨道周期约为10年，并将在不久的将来产生L矮星的动力质量。
We report the discovery of two faint ultracool companions to the nearby (d ~ 17.9 pc) young G2 V star HD 130948 (HR 5534, HIP 72567) using the Hokupa'a adaptive optics (AO) instrument mounted on the Gemini North 8 m telescope. Both objects have the same common proper motion as the primary star as seen over a 7 month baseline and have near-IR photometric colors that are consistent with an early L classification. Near-IR spectra taken with the NIRSPEC AO instrument on the Keck II telescope reveal K I lines, FeH, and H2O band heads. Based on these spectra, we determine that both objects have a spectral type of dL2 with an uncertainty of two spectral subclasses. The position of the new companions on the H-R diagram in comparison with theoretical models is consistent with the young age of the primary star (<0.8 Gyr) estimated on the basis of X-ray activity, lithium abundance, and fast rotation. HD 130948B and C likely constitute a pair of young contracting brown dwarfs with an orbital period of about 10 yr and will yield dynamical masses for L dwarfs in the near future.