The N2K Consortium. II. A Transiting Hot Saturn around HD 149026 with a Large Dense Core
The N2K Consortium. II. A Transiting Hot Saturn around HD 149026 with a Large Dense Core
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DOI：
10.1086/449306
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发表时间：
2005-06
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影响因子：
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通讯作者：
B. Sato;Debra A. Fischer;Gregory W. Henry;G. Laughlin;R. P. Butler;Geoffrey W Marcy;S. Vogt;P. Bodenheimer;Shigeru Ida;Shigeru Ida;E. Toyota;A. Wolf;J. A. Valenti;Louis J. Boyd;John A. Johnson;Jason T. Wright;M. Ammons;S. Robinson;J. Strader;C. McCarthy;K. Tah;D. Minniti
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文献类型：
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作者：
B. Sato;Debra A. Fischer;Gregory W. Henry;G. Laughlin;R. P. Butler;Geoffrey W Marcy;S. Vogt;P. Bodenheimer;Shigeru Ida;Shigeru Ida;E. Toyota;A. Wolf;J. A. Valenti;Louis J. Boyd;John A. Johnson;Jason T. Wright;M. Ammons;S. Robinson;J. Strader;C. McCarthy;K. Tah;D. Minniti
Subaru和Keck的多普勒测量显示，V = 8.15，G 0 IV星星HD 149026的径向速度变化与土星质量的行星在2.8766天的轨道上一致。费尔伯恩天文台的测光观测在预测的会合时间探测到了三个深度为0.003等的完整凌日事件。HD 149026现在是第二亮的星星，有一颗凌日系外行星。根据恒星演化模型的插值，该星星的质量为1.3 ± 0.1 M，结合多普勒振幅K1 = 43.3 m s-1，我们得到行星质量Msin i = 0.36 MJ，轨道半径为0.042 Au。HD 149026不具有色球活性且富含金属，光谱推导的[Fe/H] =+0.36，Teff = 6147 K，log g = 4.26，v sin i = 6.0 km s-1。基于Teff和2.72 L的光度，我们推导出恒星半径为1.45 R。三次测光凌日的模型提供了85.°3 ± 1.°0的轨道倾角和（包括恒星半径的不确定性）（0.725 ± 0.05）RJ的行星半径。这颗行星的质量和半径的模型表明存在一个由比氢和氦重的元素组成的~67 M的核心。这个巨大的行星核心很难通过引力不稳定性来构建。
Doppler measurements from Subaru and Keck have revealed radial velocity variations in the V = 8.15, G0 IV star HD 149026 consistent with a Saturn-mass planet in a 2.8766 day orbit. Photometric observations at Fairborn Observatory have detected three complete transit events with depths of 0.003 mag at the predicted times of conjunction. HD 149026 is now the second-brightest star with a transiting extrasolar planet. The mass of the star, based on interpolation of stellar evolutionary models, is 1.3 ± 0.1 M☉; together with the Doppler amplitude K1 = 43.3 m s-1, we derive a planet mass M sin i = 0.36MJ and orbital radius 0.042 AU. HD 149026 is chromospherically inactive and metal-rich with spectroscopically derived [Fe/H] = +0.36, Teff = 6147 K, log g = 4.26, and v sin i = 6.0 km s-1. Based on Teff and the stellar luminosity of 2.72 L☉, we derive a stellar radius of 1.45 R☉. Modeling of the three photometric transits provides an orbital inclination of 85.°3 ± 1.°0 and (including the uncertainty in the stellar radius) a planet radius of (0.725 ± 0.05)RJ. Models for this planet mass and radius suggest the presence of a ~67 M⊕ core composed of elements heavier than hydrogen and helium. This substantial planet core would be difficult to construct by gravitational instability.