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arXiv 2005.10318astro-ph.EP
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潜在宜居系外行星所在系外行星系统的潮汐演化。LHS-1140 b-c和K2-18 b-c的病例

Tidal evolution of exoplanetary systems hosting Potentially Habitable Exoplanets. The cases of LHS-1140 b-c and K2-18 b-c

Gabriel O. Gomes, Sylvio Ferraz-Mello

摘要:

我们提出了一个模型来研究由两个低质量行星绕一颗恒星旋转组成的三体系统的长期和潮汐演变,在这种情况下,机构的旋转轴总是垂直于轨道平面。潮汐理论使我们能够研究坚硬的类地行星和主要是气态的类海王星行星的自旋和轨道演化。该模型被应用于研究两个最近发现的含有潜在宜居系外行星(PHE)的系外行星系统:LHS-1140 b-c和K2-18 b-c。对于前一个系统,我们表明,LHS-1140 b和c必须在近圆轨道。对于K2-18 b-c,结合轨道演化时间尺度和目前对K2-18 b的偏心率估计,我们可以得出结论,内行星(K2-18 c)必须是一个类似海王星的气态天体。只有这样,K2-18 b的偏心率才能在最近的工作($e=0.20 \pm 0.08$)中估计的值的范围内,只要K2-18 b的均匀粘性系数大于$2.4 \times 10^{19} \ \textrm{Pa s}$(这是刚体的一个特征值),并假定这种系统的年龄为某个Gyr。

英文摘要:

We present a model to study secularly and tidally evolving three-body systems composed by two low-mass planets orbiting a star, in the case where the bodies rotation axes are always perpendicular to the orbital plane. The tidal theory allows us to study the spin and orbit evolution of both stiff Earth-like planets and predominantly gaseous Neptune-like planets. The model is applied to study two recently-discovered exoplanetary systems containing potentially habitable exoplanets (PHE): LHS-1140 b-c and K2-18 b-c. For the former system, we show that both LHS-1140 b and c must be in nearly-circular orbits. For K2-18 b-c, the combined analysis of orbital evolution timescales with the current eccentricity estimation of K2-18 b allows us to conclude that the inner planet (K2-18 c) must be a Neptune-like gaseous body. Only this would allow for the eccentricity of K2-18 b to be in the range of values estimated in recent works ($e=0.20 \pm 0.08$), provided that the uniform viscosity coefficient of K2-18 b is greater than $2.4 \times 10^{19} \ \textrm{Pa s}$ (which is a value characteristic of stiff bodies) and supposing that such system has an age of some Gyr.

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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