A Unique Solution of Planet and Star Parameters from an Extrasolar Planet Transit Light Curve
A Unique Solution of Planet and Star Parameters from an Extrasolar Planet Transit Light Curve
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DOI：
10.1086/346105
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发表时间：
2002-06
期刊：
影响因子：
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通讯作者：
S. Seager;G. Mallén-Ornelas
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文献类型：
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作者：
S. Seager;G. Mallén-Ornelas
如果行星具有圆形轨道，并且在临边变暗可忽略不计的带通中观察到光变曲线，则来自具有两次或多次凌日的行星过日光变曲线有行星和恒星参数的唯一解。由于多种原因，这种独特解决方案的存在对于当前的行星凌日调查非常有用。首先，有一个解析解可以快速估计参数，特别是 Rp。其次，恒星密度可以仅从凌日光曲线中得出。然后，恒星密度可用于立即排除巨星（因此比行星伴星大得多），并且即使考虑到稍微进化的恒星，也可用于设定恒星和行星半径的上限。第三，考虑到中心恒星的光谱类型，可以在很大程度上从凌日光曲线中排除存在污染食系统以模拟行星凌日的额外完全混合恒星的存在。第四，可以根据单次凌日光曲线和测量的光谱类型来估计周期。所有这些应用程序都可以用来选择最佳的行星凌日候选者，以便通过径向速度跟踪进行质量测定。为了在实践中使用这些应用，光变曲线的光度精度和时间采样必须很高（两次凌日光变曲线的精度优于 0.005 mag 精度和 5 分钟时间采样）。
There is a unique solution of the planet and star parameters from a planet transit light curve with two or more transits if the planet has a circular orbit and the light curve is observed in a bandpass where limb darkening is negligible. The existence of this unique solution is very useful for current planet transit surveys for several reasons. First, there is an analytic solution that allows a quick parameter estimate, in particular of Rp. Second, the stellar density can be uniquely derived from the transit light curve alone. The stellar density can then be used to immediately rule out a giant star (and hence a much larger than planetary companion) and can also be used to put an upper limit on the stellar and planet radius even considering slightly evolved stars. Third, the presence of an additional fully blended star that contaminates an eclipsing system to mimic a planet transit can be largely ruled out from the transit light curve given a spectral type for the central star. Fourth, the period can be estimated from a single-transit light curve and a measured spectral type. All of these applications can be used to select the best planet transit candidates for mass determination by radial velocity follow-up. To use these applications in practice, the photometric precision and time sampling of the light curve must be high (better than 0.005 mag precision and 5 minute time sampling for a two-transit light curve).