AN ULTRACOOL STAR’S CANDIDATE PLANET
AN ULTRACOOL STAR’S CANDIDATE PLANET
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一颗超酷恒星的候选行星
DOI：
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发表时间：
2009
期刊：
影响因子：
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通讯作者：
S. Shaklan
中科院分区：
文献类型：
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作者：
S. Pravdo;S. Shaklan
我们在这里报道了第一颗围绕一颗超冷矮星的行星的发现。这也是通过天体测量发现的第一颗围绕主序恒星的太阳系外巨行星。检测的统计意义体现在两个方面。首先，天文测量运动符合视差和自行运动模型的概率为2×10−8。其次，周期图分析表明，虚警概率为3×10−5，表明所发现的周期是随机生成的。在最可能的模型中，行星质量为M2=6.4(+2.6，−3.1)木星质量(MJ)，轨道周期为P=0.744(+0.013，−0.008)年。在不太可能的模型中，过去的径向速度(RV)测量排除了高于13MJ行星质量极限的伴生质量，除非系统RV超过当前上限的两倍，并且从未观察到近星轨道阶段。这个新的行星系统之所以引人注目，部分原因是它的恒星VB10接近恒星的质量下限。我们的天体测量观测提供了一种动态质量测量，并将使我们能够及时地面对这些系统及其成员的形成和演化的理论模型。因此，我们增加了行星系统的多样性，增加了为数不多的已知M矮行星。像VB10b这样的行星可能是数量最多的行星类型，因为M星占所有恒星的70%。到目前为止，它们仍然是隐藏的，因为占主导地位的RV行星发现技术对这些昏暗的红色系统相对不敏感。
We report here the discovery of the first planet around an ultracool dwarf star. It is also the first extrasolar giant planet astrometrically discovered around a main-sequence star. The statistical significance of the detection is shown in two ways. First, there is a 2 × 10−8 probability that the astrometric motion fits a parallax-and-proper-motion-only model. Second, periodogram analysis shows a false alarm probability of 3 × 10−5 that the discovered period is randomly generated. The planetary mass is M2 = 6.4 (+2.6,−3.1) Jupiter-masses (MJ), and the orbital period is P = 0.744 (+0.013,−0.008) yr in the most likely model. In less likely models, companion masses that are higher than the 13 MJ planetary mass limit are ruled out by past radial velocity (RV) measurements unless the system RV is more than twice the current upper limits and the near-periastron orbital phase was never observed. This new planetary system is remarkable, in part, because its star, VB 10, is near the lower mass limit for a star. Our astrometric observations provide a dynamical mass measurement and will in time allow us to confront the theoretical models of formation and evolution of such systems and their members. We thus add to the diversity of planetary systems and to the small number of known M-dwarf planets. Planets such as VB 10b could be the most numerous type of planets because M stars comprise >70% of all stars. To date they have remained hidden since the dominant RV planet-discovery technique is relatively insensitive to these dim, red systems.