论文标题
关于行星含性对系外行星研究的影响
On the Effects of Planetary Oblateness on Exoplanet Studies
论文作者
论文摘要
在研究转运系外行星时，通常假设球形行星形状。但是，短期旋转周期会导致行星在其赤道上凸起，就像土星一样，赤道半径比其极性半径大10％。随着新一代工具的在线，重要的是要持续评估模型的基本假设，以确保可靠和准确的推论。我们分析已知的过渡行星的大量样品，并计算其预期信号强度，如果它们要植入。我们发现，对于低于100ppm的噪声水平，多达100个行星可能具有可检测到的底漆。我们还研究了拟合球形行星模型对合成扁平曲面的影响。我们发现，这会偏向于检索到的参数，几个标准偏差> 0.1-0.2。当试图将污垢模型拟合到球形和扁平曲线时，我们发现这种拟合的敏感性与SNR以及数据的时间采样都相关，这可以掩盖涂抹信号。对于这些数量的开普勒观察值的典型值，很难排除小于〜0.25的填充值。这可能使行星密度的精度为10-15％，这可能是植物的。最后，我们发现，一个进攻剂的行星具有通过过境时序变化模仿长周期伴侣的签名，从而在10秒钟的水平上引起偏移。
When studying transiting exoplanets it is common to assume a spherical planet shape. However short rotational periods can cause a planet to bulge at its equator, as is the case with Saturn whose equatorial radius is almost 10% larger than its polar radius. As a new generation of instruments comes online, it is important to continually assess the underlying assumptions of models to ensure robust and accurate inferences. We analyze bulk samples of known transiting planets and calculate their expected signal strength if they were to be oblate. We find that for noise levels below 100ppm, as many as 100 planets could have detectable oblateness. We also investigate the effects of fitting spherical planet models to synthetic oblate lightcurves. We find that this biases the retrieved parameters by several standard deviations for oblateness values > 0.1-0.2. When attempting to fit an oblateness model to both spherical and oblate lightcurves, we find that the sensitivity of such fits is correlated with both the SNR as well as the time sampling of the data, which can mask the oblateness signal. For typical values of these quantities for Kepler observations, it is difficult to rule out oblateness values less than ~0.25. This results in an accuracy wall of 10-15% for the density of planets which may be oblate. Finally, we find that a precessing oblate planet has the ability to mimic the signature of a long-period companion via transit timing variations, inducing offsets at the level of 10s of seconds.
