Sara Seager2014-03-17 4:57 PM

源自外太阳系行星穿越光变曲线的行星和恒星参数的唯一解  On the Unique Solution of Planet and Star Parameters from an Extrasolar Planet Transit Light Curve 

论文摘要

假如该行星具有圆形轨道且光变曲线能够在可忽略临边变暗的带通中观测到,则源自具有两个以上行星穿越的光变曲线的行星和恒星参数具有唯一解。这种唯一解的存在对当前行星过境探索有以极有用的几个原因。

首先存在允许快速参数估计尤其是Rp的解析解。

其次,恒星密度可以单独从穿越光变曲线中独自导出。这一恒星密度可以立即排除巨恒星(因此远大于类行星伴星)且还可用来给恒星和行星半径设置上限,甚至可将微演化恒星考虑在内。

第三, 我们可以基于中央恒星特定光谱类型根据传播光变曲线来极大排除那些额外存在的会对模拟行星过境食变星系统产生损害的充分混合恒星。

第四,我们可以从单一传播光变曲线和测得光谱类型来估计周期。利用所有这些应用,我们可以通过随后径向速度来选择用于质量测定的最佳穿越行星。在实践应用中,测光精度和光变曲线的时间取样必须要高(最好高于0.005 MAG精度以及对双传播光曲线的5分钟采样计时)。


Abstract

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).

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Sara Seager

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