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arXiv 2310.18754astro-ph.EP
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可能宜居的行星K2-18 b在有无拟议内部伴星情况下的长期轨道动力学

Secular Orbital Dynamics of the Possibly Habitable Planet K2-18 b with and without the Proposed Inner Companion

Valeri V. Makarov, Alexey Goldin

AI总结:

本文研究可能宜居行星K2-18 b在单行星和含4:1共振内部伴星两种构型下的长期轨道动力学,揭示伴星导致数千年尺度的偏心率和倾角周期性交换,并讨论其对气候宜居性和米兰科维奇周期的影响。

摘要:

凌星行星K2-18 b是相对邻近的、可能孕育生物生命的世界中最具希望的候选体之一。本文利用理论方法和纯数值技术,针对两种可能的构型研究了该行星的长期轨道演化:一种是单一行星绕主星运行,另一种是包含拟议内部行星的双行星系统,该内部行星接近4:1平均运动共振关系。研究重点放在偏心率和轨道倾角的长期变化上,这些变化对该行星的气候稳定性至关重要。研究证明,带有内部伴星的行星K2-18 b的长期轨道动力学可以通过在数千年时间尺度上的周期性偏心率和倾角交换来准确表示。预计单一行星不会经历快速的轨道变化,因为弱得多的潮汐和自转驱动的摄动主要体现在缓慢的近日点进动和交点进动上。在恒星年龄的时间尺度上,轨道的潮汐衰减过于微小,可以忽略不计。然而,如果单一行星K2-18 b像地球一样自转速度快于平均运动,并且其自转轴倾角受到一颗假想卫星的影响而发生倾斜,那么该行星的宜居性条件将得到显著改善。本文还讨论了两种构型下该宜居行星气候的米兰科维奇周期。

英文摘要:

The transiting planet K2-18 b is one of the best candidates for a relatively nearby world harboring biological life. The long-term orbital evolution of this planet is investigated using theoretical and purely numerical techniques for two possible configurations: a single planet orbiting the host star, and a two-planet system including the proposed inner planet close to the 4:1 mean motion rationalization. The emphasis is made on the secular changes of eccentricity and orbital inclination, which are important for the climate stability of the planet. It is demonstrated that the secular orbital dynamics of planet K2-18 b with an internal companion are accurately represented by the periodic eccentricity and inclination exchange on the time scales of a few Kyr. A single planet is not expected to experience fast orbital changes, with the much weaker tidal and rotation-driven perturbations mostly reflecting in a slow periastron and nodal precession. The tidal decay of the orbit is too insignificant on the time scale of the stellar age. However, the conditions for the habitability of a single K2-18 b planet are much improved if, like the Earth, it rotates faster than the mean motion and its rotation angle is tilted by a hypothetical moon. Milankovi{ć}'s cycles of the habitable planet's climate are discussed for both configurations.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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