根据明亮行星宿主恒星的恒星“闪烁”亮度变化推断较大的行星半径
Larger Planet Radii Inferred from Stellar "Flicker" Brightness Variations of Bright Planet Host Stars
摘要：
大多数太阳系外行星都是通过它们对母恒星的影响而被发现的，通常是通过引力（多普勒方法）或通过行星阻挡恒星的一部分时亮度的小幅下降（凌日方法）。因此，我们知道太阳系外行星的质量和半径的准确性直接取决于我们对恒星质量和半径的了解程度，后者通常由测量的恒星表面重力logg确定。最近的工作表明，恒星的短时间尺度亮度变化（“闪烁”）可用于测量logg，精度高达约0.1-0.2 dex（Bastien等人，2013年）。在这里，我们使用闪烁测量289个明亮的（Kepmag<13）候选行星宿主恒星，Teff=4500-6650 K，以重新评估恒星参数，并确定对衍生行星属性的影响。重新评估显示，对于最明亮的行星宿主恒星，存在一种天体物理学的偏差，这种偏差使恒星样本被演化的恒星污染：近50%的明亮行星宿主恒星是次巨星。因此，恒星的半径，以及围绕这些恒星运行的行星的半径，平均比以前的测量结果大20-30%。
英文摘要：
Most extrasolar planets have been detected by their influence on their parent star, typically either gravitationally (the Doppler method) or by the small dip in brightness as the planet blocks a portion of the star (the transit method). Therefore, the accuracy with which we know the masses and radii of extrasolar planets depends directly on how well we know those of the stars, the latter usually determined from the measured stellar surface gravity, logg. Recent work has demonstrated that the short-timescale brightness variations ("flicker") of stars can be used to measure logg to a high accuracy of ~0.1-0.2 dex (Bastien et al. 2013). Here, we use flicker measurements of 289 bright (Kepmag<13) candidate planet-hosting stars with Teff=4500-6650 K to re-assess the stellar parameters and determine the resulting impact on derived planet properties. This re-assessment reveals that for the brightest planet-host stars, an astrophysical bias exists that contaminates the stellar sample with evolved stars: nearly 50% of the bright planet-host stars are subgiants. As a result, the stellar radii, and hence the radii of the planets orbiting these stars, are on average 20-30% larger than previous measurements had suggested.
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