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Higher Compact Multiple Occurrence around Metal-poor M-dwarfs and Late-K-dwarfs
The Astronomical Journal ( IF 5.3 ) Pub Date : 2021-03-25 , DOI: 10.3847/1538-3881/abe70b
Sophie G. Anderson 1 , Jason A. Dittmann 2 , Sarah Ballard 3 , Megan Bedell 4
Affiliation  

The planet–metallicity correlation serves as a potential link between exoplanet systems as we observe them today and the effects of bulk composition on the planet formation process. Many observers have noted a tendency for Jovian planets to form around stars with higher metallicities; however, there is no consensus on a trend for smaller planets. Here, we investigate the planet–metallicity correlation for rocky planets in single- and multi-planet systems around Kepler M-dwarf and late-K-dwarf stars. Due to molecular blanketing and the dim nature of these low-mass stars, it is difficult to make direct elemental abundance measurements via spectroscopy. We instead use a combination of accurate and uniformly measured parallaxes and photometry to obtain relative metallicities and validate this method with a subsample of spectroscopically determined metallicities. We use the Kolmogorov–Smirnov (K-S) test, Mann–Whitney U-test, and Anderson–Darling (AD) test to compare the compact multiple planetary systems with single-transiting planet systems and systems with no detected transiting planets. We find that the compact multiple planetary systems are derived from a statistically more metal-poor population, with a p-value of 0.015 in the K-S test, a p-value of 0.005 in the Mann–Whitney U-test, and a value of 2.574 in the AD test statistic, which exceeds the derived threshold for significance by a factor of 25. We conclude that metallicity plays a significant role in determining the architecture of rocky planet systems. Compact multiples either form more readily, or are more likely to survive on gigayear timescales, around metal-poor stars.



中文翻译:

贫金属 M 矮星和晚 K 矮星周围的高致密多次出现

行星金属丰度相关性是我们今天观察到的系外行星系统与大块组成对行星形成过程的影响之间的潜在联系。许多观察者已经注意到,木星行星倾向于在金属丰度较高的恒星周围形成。然而,对于较小行星的趋势尚未达成共识。在这里,我们研究了围绕开普勒 M 矮星和晚 K 矮星的单行星和多行星系统中岩石行星的行星金属丰度相关性。由于这些低质量恒星的分子覆盖和暗淡的性质,很难通过光谱法进行直接的元素丰度测量。相反,我们使用准确且均匀测量的视差和光度法的组合来获得相对金属丰度,并使用光谱确定的金属丰度子样本验证该方法。我们使用 Kolmogorov-Smirnov (KS) 检验、Mann-Whitney U-test 和 Anderson-Darling (AD) 检验来比较紧凑的多行星系统与单凌日行星系统和未检测到凌日行星的系统。我们发现紧凑的多行星系统来自统计上更缺乏金属的人口,具有p在KS测试0.015 -值,一个p 0.005在曼-惠特尼U检验-值,并在AD检验统计量的一个值2.574,其通过一个25系数超过意义派生阈我们得出结论,金属丰度在确定岩石行星系统的结构中起着重要作用。致密倍数要么更容易形成,要么更有可能在缺乏金属的恒星周围以千兆年的时间尺度生存。

更新日期:2021-03-25
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