Homogeneous studies of transiting extrasolar planets - III. Additional planets and stellar models
Homogeneous studies of transiting extrasolar planets - III. Additional planets and stellar models
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DOI：
10.1111/j.1365-2966.2010.17231.x
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发表时间：
2010-06
影响因子：
4.8
通讯作者：
J. Southworth
中科院分区：
文献类型：
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作者：
J. Southworth
通过对已发表数据的均匀分析，我得出了30个凌日系外行星系统的物理特性。用jktebop代码对光曲线进行建模，特别注意了边暗化处理、轨道偏心和误差分析。一些星系发出的光受到附近微弱恒星的污染，如果忽略这些污染，结果就会出现系统性偏差。我指出，仅用过境光曲线来解释这一点实际上是不可能的：光曲线的解必须受到污染光量的测量的限制。5%的污染足以使行星半径2%的测量值过低。这30个凌日系统的物理性质是通过将理论恒星模型的预测表内插得到的，以找到与光曲线参数和测量的恒星速度振幅、温度和金属丰度的最佳匹配。统计误差通过摄动分析传播，该分析为每个输出参数构建完整的误差预算。这些误差预算用于编制一份系统清单，这些系统将受益于额外的光度或光谱测量。通过使用五组独立的低质量恒星的理论预测来评估由于包含恒星模型而产生的系统误差。这种模型依赖性为测量系统物理性质的准确性设定了一个下限，从恒星质量的1%到行星质量的0.6%，以及其他量的0.3%不等。恒星密度、行星表面重力和平衡温度不受这种模型依赖性的影响。通过比较WASP-11/HAT-P-10系统的两篇发现论文，对这些系统误差进行了外部测试：这两篇研究在评估组件半径的比例和恒星的有效温度方面存在差异。我发现行星表面重力和质量与轨道周期的相关性分别只有3.1σ和2.3σ的显著性水平。自第二篇论文以来，后者的重要性并没有随着新数据的增加而增加。基于萨夫诺夫数的两类行星的划分越来越模糊。这里研究的大多数天体都将受益于光度和光谱观测的改进，以及我们对低质量恒星及其有效温标的理解的改进。
I derive the physical properties of 30 transiting extrasolar planetary systems using a homogeneous analysis of published data. The light curves are modelled with the jktebop code, with special attention paid to the treatment of limb darkening, orbital eccentricity and error analysis. The light from some systems is contaminated by faint nearby stars, which if ignored will systematically bias the results. I show that it is not realistically possible to account for this using only transit light curves: light-curve solutions must be constrained by measurements of the amount of contaminating light. A contamination of 5 per cent is enough to make the measurement of a planetary radius 2 per cent too low. The physical properties of the 30 transiting systems are obtained by interpolating in tabulated predictions from theoretical stellar models to find the best match to the light-curve parameters and the measured stellar velocity amplitude, temperature and metal abundance. Statistical errors are propagated by a perturbation analysis which constructs complete error budgets for each output parameter. These error budgets are used to compile a list of systems which would benefit from additional photometric or spectroscopic measurements. The systematic errors arising from the inclusion of stellar models are assessed by using five independent sets of theoretical predictions for low-mass stars. This model dependence sets a lower limit on the accuracy of measurements of the physical properties of the systems, ranging from 1 per cent for the stellar mass to 0.6 per cent for the mass of the planet and 0.3 per cent for other quantities. The stellar density and the planetary surface gravity and equilibrium temperature are not affected by this model dependence. An external test on these systematic errors is performed by comparing the two discovery papers of the WASP-11/HAT-P-10 system: these two studies differ in their assessment of the ratio of the radii of the components and the effective temperature of the star. I find that the correlations of planetary surface gravity and mass with orbital period have significance levels of only 3.1σ and 2.3σ, respectively. The significance of the latter has not increased with the addition of new data since Paper II. The division of planets into two classes based on Safronov number is increasingly blurred. Most of the objects studied here would benefit from improved photometric and spectroscopic observations, as well as improvements in our understanding of low-mass stars and their effective temperature scale.