Toward Detection of Exoplanetary Rings via Transit Photometry: Methodology and a Possible Candidate
Toward Detection of Exoplanetary Rings via Transit Photometry: Methodology and a Possible Candidate
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通过凌日光度法检测系外行星环：方法论和可能的候选者
DOI：
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发表时间：
2017
期刊：
影响因子：
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通讯作者：
Y. Suto
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文献类型：
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作者：
M. Aizawa;S. Uehara;K. Masuda;H. Kawahara;Y. Suto
系外行星环的探测仍然是系外行星科学领域最具吸引力但具有挑战性的目标之一。我们提出了一种方法，通过对长周期行星的凌日光度测量来实现对系外环的系统搜索。这种方法依赖于我们开发的一种精确的积分方案，该方案用于计算环形行星的过境光曲线。我们将这种方法应用于开普勒数据中的89个长周期行星候选，以便估计和/或设定可能环的参数上限。虽然我们的大多数样本没有足够的信噪比(S/NS)来对环参数施加有意义的限制，但我们发现，假设一个掠食轨道和一个倾斜的环，具有较高S/NS的六个系统与存在大于行星半径1.5倍的环是不一致的。此外，我们确定了五个初步候选系统，它们的光曲线呈现环状特征。在排除了由于附近恒星的污染而导致的四个假阳性后，我们确定KIC 10403228是一个合理的环状行星候选者。它的光曲线与环形行星模型的系统参数拟合表明，有两种可能的解决方案对应于一颗带有倾斜光环的类似土星的行星。还有另外两种可能的情况来解释这些数据；一个是环绕恒星的圆盘，另一个是三层结构。由于不确定因素很大，我们不能在三种模式中选择一种具体的模式。
The detection of a planetary ring of exoplanets remains one of the most attractive, but challenging, goals in the field of exoplanetary science. We present a methodology that implements a systematic search for exoplanetary rings via transit photometry of long-period planets. This methodology relies on a precise integration scheme that we develop to compute a transit light curve of a ringed planet. We apply the methodology to 89 long-period planet candidates from the Kepler data so as to estimate, and/or set upper limits on, the parameters of possible rings. While the majority of our samples do not have sufficient signal-to-noise ratios (S/Ns) to place meaningful constraints on ring parameters, we find that six systems with higher S/Ns are inconsistent with the presence of a ring larger than 1.5 times the planetary radius, assuming a grazing orbit and a tilted ring. Furthermore, we identify five preliminary candidate systems whose light curves exhibit ring-like features. After removing four false positives due to the contamination from nearby stars, we identify KIC 10403228 as a reasonable candidate for a ringed planet. A systematic parameter fit of its light curve with a ringed planet model indicates two possible solutions corresponding to a Saturn-like planet with a tilted ring. There also remain two other possible scenarios accounting for the data; a circumstellar disk and a hierarchical triple. Due to large uncertain factors, we cannot choose one specific model among the three.