Using Stellar Limb-Darkening to Refine the Properties of HD 209458b
Using Stellar Limb-Darkening to Refine the Properties of HD 209458b
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使用 Stellar Limb-Darkening 来优化 HD 209458b 的属性
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发表时间：
2006
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通讯作者：
R. Gilliland
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作者：
H. Knutson;D. Charbonneau;R. Noyes;T. Brown;R. Gilliland
我们使用多波段测光，以完善过境行星系统HD 209458的行星半径和轨道倾角的估计。我们收集了1066光谱在四个不同的过渡与STIS光谱仪的哈勃太空望远镜使用两个光栅的分辨率R = 1500和组合波长范围为290-1030 nm。我们将光谱分成10个分光光度带通，每个光栅5个，每个光栅内的波长跨度相等，并同时在所有带通上拟合过渡曲线。在我们的拟合中，我们使用恒星边缘变暗的理论值来进一步限制行星半径。我们发现HD 209458 b的半径为（1.320 ± 0.025）RJup，比目前的估计精确2倍。我们还得到了改进的估计轨道周期P和过境中心的时间TC。虽然原则上STIS数据的光子限制精度应该允许我们测量单个凌日的时间到2-7 s的精度，但我们发现恒星边缘变暗系数的不确定性和数据中的残余噪声使这些测量降低到±14 s的典型精度。在这个水平的误差，我们发现没有显着的变化，在这项工作中检查的八个事件的时间。
We use multiband photometry to refine estimates for the planetary radius and orbital inclination of the transiting planet system HD 209458. We gathered 1066 spectra over four distinct transits with the STIS spectrometer on the Hubble Space Telescope using two gratings with a resolution R = 1500 and a combined wavelength range of 290-1030 nm. We divide the spectra into 10 spectrophotometric bandpasses, five for each grating, of equal wavelength span within each grating, and fit a transit curve over all bandpasses simultaneously. In our fit we use theoretical values for the stellar limb-darkening to further constrain the planetary radius. We find that the radius of HD 209458b is (1.320 ± 0.025)RJup, which is a factor of 2 more precise than current estimates. We also obtain improved estimates for the orbital period P and time of center of transit TC. Although in principle the photon-limited precision of the STIS data should allow us to measure the timing of individual transits to a precision of 2-7 s, we find that uncertainties in the stellar limb-darkening coefficients and residual noise in the data degrade these measurements to a typical precision of ±14 s. Within this level of error, we find no significant variations in the timing of the eight events examined in this work.