A Determination of the Spin-Orbit Alignment of the Anomalously Dense Planet Orbiting HD 149026
A Determination of the Spin-Orbit Alignment of the Anomalously Dense Planet Orbiting HD 149026
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异常致密行星轨道 HD 149026 的自旋轨道对准的测定
DOI：
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发表时间：
2007
期刊：
影响因子：
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通讯作者：
S. Vogt
中科院分区：
文献类型：
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作者：
A. Wolf;G. Laughlin;G. Henry;D. Fischer;G. Marcy;P. Butler;S. Vogt
我们报告了用凯克望远镜对HD 149026进行的35次径向速度测量。在这些测量中，有15次是在2005年6月25日伴随行星HD 149026 b过境时进行的。这些速度提供了罗西特-麦克劳克林效应的高节奏观测，当行星遮住旋转恒星表面的一部分时，光球线轮廓发生变化。我们结合这些径向速度与以前公布的径向速度和光度数据集，并得出一个复合的最佳拟合模型的恒星-行星系统联合收割机。该模型证实并改进了先前发表的轨道参数，包括非常小的行星半径，行星质量和轨道倾角，发现Rp/RJup = 0.718 ± 0.065，Mp/MJup = 0.352 ± 0.025，和I = 86.1° ± 1.4°。行星的质量和半径的测定意味着行星的平均密度为1.18 g cm-3。新的数据还允许确定视恒星赤道和轨道平面之间的角度，我们将其限制为λ = -12° ± 15°。
We report 35 radial velocity measurements of HD 149026 taken with the Keck Telescope. Of these measurements, 15 were made during the transit of the companion planet HD 149026b, which occurred on 2005 June 25. These velocities provide a high-cadence observation of the Rossiter-McLaughlin effect, the shifting of photospheric line profiles that occurs when a planet occults a portion of the rotating stellar surface. We combine these radial velocities with previously published radial velocity and photometric data sets and derive a composite best-fit model for the star-planet system. This model confirms and improves previously published orbital parameters, including the remarkably small planetary radius, the planetary mass, and the orbital inclination, found to be Rp/RJup = 0.718 ± 0.065, Mp/MJup = 0.352 ± 0.025, and I = 86.1° ± 1.4°, respectively. Together the planetary mass and radius determinations imply a mean planetary density of 1.18 g cm-3. The new data also allow for the determination of the angle between the apparent stellar equator and the orbital plane, which we constrain to be λ = -12° ± 15°.