ON THE ANOMALOUS RADII OF THE TRANSITING EXTRASOLAR PLANETS
ON THE ANOMALOUS RADII OF THE TRANSITING EXTRASOLAR PLANETS
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DOI：
10.1088/2041-8205/729/1/l7
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发表时间：
2011-01
期刊：
影响因子：
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通讯作者：
G. Laughlin;M. Crismani;F. Adams
中科院分区：
文献类型：
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作者：
G. Laughlin;M. Crismani;F. Adams
我们提出了一个系统的评价90个良好的特征凌日系外巨行星的观测半径和相应的模型半径之间的协议。我们的模型半径是从以前发表的计算无核巨行星，已达到其渐近半径，并已列出了一系列的行星质量和平衡温度。(We报告准确表示模型的二维多项式拟合函数。）正如预期的那样，模型半径提供了一个统计上显着的改进，超过了巨行星的大小完全独立于质量和有效温度的零假设。然而，众所周知，基准模型提供的解释是不够的;行星半径异常与行星平衡温度密切相关。我们发现，半径异常有一个最佳拟合依赖，α = 1.4 ± 0.6。将该关系扩展到模型半径中导致半径相关性中的基本上更少的分散。额外的温度依赖性代表了对热超导体理论模型的重要约束。使用简单的缩放参数，我们发现支持Batygin和史蒂文森的假设，这种相关性可以归因于行星加热机制，是介导的行星磁场和近地表流之间的磁流体动力学耦合，伴随着欧姆耗散在绝热深度。此外，我们发现，温度的依赖性可能太强，承认动能加热作为异常能量产生的主要来源，在大多数观察到的过境行星。
We present a systematic evaluation of the agreement between the observed radii of 90 well-characterized transiting extrasolar giant planets and their corresponding model radii. Our model radii are drawn from previously published calculations of coreless giant planets that have attained their asymptotic radii, and which have been tabulated for a range of planet masses and equilibrium temperatures. (We report a two-dimensional polynomial fitting function that accurately represents the models.) As expected, the model radii provide a statistically significant improvement over a null hypothesis that the sizes of giant planets are completely independent of mass and effective temperature. As is well known, however, fiducial models provide an insufficient explanation; the planetary radius anomalies, , are strongly correlated with planetary equilibrium temperature. We find that the radius anomalies have a best-fit dependence, , with α = 1.4 ± 0.6. Incorporating this relation into the model radii leads to substantially less scatter in the radius correlation. The extra temperature dependence represents an important constraint on theoretical models for hot Jupiters. Using simple scaling arguments, we find support for the hypothesis of Batygin & Stevenson that this correlation can be attributed to a planetary heating mechanism that is mediated by magnetohydrodynamic coupling between the planetary magnetic field and near-surface flow that is accompanied by ohmic dissipation at adiabatic depth. Additionally, we find that the temperature dependence is likely too strong to admit kinetic heating as the primary source of anomalous energy generation within the majority of the observed transiting planets.