Infrared spectroscopy of a brown dwarf companion candidate near the young star GSC 08047-00232 in Horologium
Infrared spectroscopy of a brown dwarf companion candidate near the young star GSC 08047-00232 in Horologium
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钟表中年轻恒星 GSC 08047-00232 附近一颗褐矮星候选伴星的红外光谱
DOI：
10.1051/0004-6361:20035713
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发表时间：
2004
影响因子：
6.5
通讯作者：
E. Guenther
中科院分区：
文献类型：
--
作者：
R. Neuhaeuser;E. Guenther
我们给出了位于年轻星星GSC 08047-00232以北3 °的伴星候选者的红外H -和Nd K-波段光谱，它可能是附近年轻的钟表星协的成员。根据先前获得的JHK波段颜色和主星与伴星之间的星等差异，后者很可能是亚恒星（诺伊豪泽等人，2000），光谱类型大致为JHK颜色的M 7−L 9（Chauvin等人，2003）。现在用ISAAC在VLT上获得的H -a ndK波段光谱，发现伴星的光谱类型是M 6−9.5。假设它的年龄和距离与主星星相同（50 ~ 85秒差距），则伴星的质量为木星质量的1.25倍，因此它确实是亚恒星。在TWA-5 B和HR 7329 B之后，这是第三颗围绕附近（≤100 pc）年轻（≤ 1亿年）星星的褐矮星伴星。在三个年轻的近星协中的79颗恒星周围，总共有三颗被证实的褐矮星伴星（任何质量，间隔≥50 Au），对应的频率为6 ± 4%（对缺失的伴星进行了校正，这些伴星几乎与主星星在同一视线上，而不是被很好地分离），如果双星与场星具有相同的质量函数，则与预期一致。因此，似乎在宽距离上没有棕矮星沙漠。
We present infrared H -a ndK-band spectra of a companion candidate 3 �� north of the young star GSC 08047-00232, a probable member of the nearby young Horologium association. From previously obtained JHK-band colors and the magnitude difference between primary and companion candidate, the latter could well be substellar (Neuhauser et al. 2000) with the spectral type being roughly M 7−L 9 from the JHK colors (Chauvin et al. 2003). With the H -a ndK-band spectra now obtained with ISAAC at the VLT, the spectral type of the companion candidate is found to be M 6−9.5. Assuming the same age and distance as for the primary star (∼35 Myr, 50 to 85 pc), this yields a mass of ∼25 Jupiter masses for the companion, hence indeed substellar. After TWA-5 B and HR 7329 B, this is the third brown dwarf companion around a nearby (≤100 pc) young (≤100 Myr) star. A total of three confirmed brown dwarf companions (any mass, separation ≥50 AU) around 79 stars surveyed in three young nearby associations corresponds to a frequency of 6 ± 4% (with a correction for missing companions which are almost on the same line-of-sight as the primary star instead of being separated well), consistent with the expectation, if binaries have the same mass function as field stars. Hence, it seems that there is no brown dwarf desert at wide separations.