论文标题
K2-290A中逆行多个星际系统的混乱历史由遥远的恒星驱动
The chaotic history of the retrograde multi-planet system in K2-290A driven by distant stars
论文作者
论文摘要
最近发现，Star K2-290a的赤道倾向于124 +/- 6度，相对于其两个已知的过渡行星的轨道。在〜100 au处的伴侣恒星B的存在表明，原始磁盘的出生可能已经倾斜，从而为该多行星系统的特殊逆行状态提供了解释。在这项工作中，我们表明不需要原始的未对准，并且观察到的逆行状态是混乱的恒星倾斜的倾斜进化的自然结果，这是由于磁盘分散后很久以来〜2000 au驱动的。恒星C驱动内部二进制轨道上的偏心率和/或倾斜度振荡，从而导致恒星自旋和行星世俗模式之间的周期性共振通道的广泛混乱。基于人群综合研究，我们发现观察到的恒星斜率在系统的40-70％中达到了，使该机制成为世俗动力学的强大结果，无论中心恒星的旋转历史如何。这项工作突出了非常遥远的同伴在近距离行星和宿主恒星的旋转演变上可以发挥的异常作用，并在数十亿轨道上连接了四个数量级的距离。我们最终评论了其他系外行星系统的应用程序，包括广泛的二进制文件的多行星系统。
The equator of star K2-290A was recently found to be inclined by 124+/-6 degrees relative to the orbits of both its known transiting planets. The presence of a companion star B at ~100 au suggested that the birth protoplanetary disk could have tilted, thus providing an explanation for the peculiar retrograde state of this multi-planet system. In this work, we show that a primordial misalignment is not required and that the observed retrograde state is a natural consequence of the chaotic stellar obliquity evolution driven by a wider-orbit companion C at ~2000 au long after the disk disperses. The star C drives eccentricity and/or inclination oscillations on the inner binary orbit, leading to widespread chaos from the periodic resonance passages between the stellar spin and planetary secular modes. Based on a population synthesis study, we find that the observed stellar obliquity is reached in ~40-70% of the systems, making this mechanism a robust outcome of the secular dynamics,regardless of the spin-down history of the central star. This work highlights the unusual role that very distant companions can have on the orbits of close-in planets and the host star's spin evolution, connecting four orders of magnitude in distance scale over billions of orbits. We finally comment on the application to other exoplanet systems, including multi-planet systems in wide binaries.
