Two massive rocky planets transiting a K-dwarf 6.5 parsecs away
Two massive rocky planets transiting a K-dwarf 6.5 parsecs away
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两颗巨大的岩石行星凌日距离为 6.5 秒差距
DOI：
10.1038/s41550-017-0056
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发表时间：
2017
期刊：
影响因子：
14.1
通讯作者：
A. Sozzetti
中科院分区：
文献类型：
--
作者：
M. Gillon;B. Demory;V. Van Grootel;F. Motalebi;C. Lovis;A. Cameron;D. Charbonneau;D. Latham;E. Molinari;F. Pepe;D. Ségransan;D. Sasselov;S. Udry;M. Mayor;G. Micela;G. Piotto;A. Sozzetti
HD 219134是一颗距离为6.5 秒的K矮星，最近在其周围发现了几颗低质量行星1，2。斯皮策太空望远镜探测到了这些行星中最内部的HD 219134 b，它的质量和半径(分别为4.5 M⊕和1.6 R⊕)与岩石成分1一致。在这里，我们报道了用斯皮策获得的新的高精度时间序列测光技术，揭示了该系统第二内部的行星HD 219134c也在凌日。对斯皮策凌日光曲线和最新的HARPS-N速度数据集的全球分析得出HD 219134 b的质量和半径估计为4.74±0.19 M⊕和1.602±0.055 R⊕，HD 219134 c的质量和半径估计为4.36±0.22 M⊕和1.511±0.047 R⊕。这两颗凌日系外行星是迄今发现的距离地球最近的凌日系外行星，由于其主恒星距离地球很近，而且体积很小(0.778±0.005 R⊙)，因此非常适合进行详细的描述(例如，质量和半径的精度只有百分之几，以及对大气性质的限制)，这可能会对几个地球质量的普遍存在的短周期行星的性质和形成机制提出重要限制。作者发现，附近的一个行星系统有两颗类地行星从它们的恒星前面经过(从我们的角度来看)。凌日的类地行星受到追捧，因为它们可以被详细描述，包括它们的大气层。在同一系统中有两个是非常罕见的。
HD 219134 is a K-dwarf star at a distance of 6.5 parsecs around which several low-mass planets were recently discovered1,2. The Spitzer Space Telescope detected a transit of the innermost of these planets, HD 219134 b, whose mass and radius (4.5 M⊕ and 1.6 R⊕ respectively) are consistent with a rocky composition1. Here, we report new high-precision time-series photometry of the star acquired with Spitzer revealing that the second innermost planet of the system, HD 219134c, is also transiting. A global analysis of the Spitzer transit light curves and the most up-to-date HARPS-N velocity data set yields mass and radius estimations of 4.74 ± 0.19 M⊕ and 1.602 ± 0.055 R⊕ for HD 219134 b, and of 4.36 ± 0.22 M⊕ and 1.511 ± 0.047 R⊕ for HD 219134 c. These values suggest rocky compositions for both planets. Thanks to the proximity and the small size of their host star (0.778 ± 0.005 R⊙)3, these two transiting exoplanets — the nearest to the Earth yet found — are well suited for a detailed characterization (for example, precision of a few per cent on mass and radius, and constraints on the atmospheric properties) that could give important constraints on the nature and formation mechanism of the ubiquitous short-period planets of a few Earth masses. The authors find that a nearby planetary system has two terrestrial planets that transit in front of their star (from our perspective). Transiting terrestrial planets are sought after, as they can be characterized in detail, including their atmospheres. Having two in the same system is very rare.
DOI：
10.1146/annurev-astro-081811-125523
发表时间：
2012-03
影响因子：
33.3
作者：
W. Kley;R. Nelson
通讯作者：
W. Kley;R. Nelson