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arXiv 1807.01474astro-ph.SRastro-ph.EP
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恒星与行星的相互作用五.对流区的动力潮汐和平衡潮汐

Star-planet interactions. V. Dynamical and equilibrium tides in convective zones

Suvrat Rao, Georges Meynet, Patrick Eggenberger, Lionel Haemmerlé, Giovanni Privitera, Cyril Georgy, Sylvia Ekström, Christoph Mordasini

摘要:

当行星从原行星盘形成,并且在盘消散之后,它们的轨道演化受潮汐相互作用、摩擦和引力拖曳以及恒星和行星质量变化的控制。这些相互作用可能会改变行星与其主星之间距离的初始分布,通过扩大原始轨道,通过收缩它(这可能会导致行星被恒星吞没)或摧毁行星。我们研究了行星在平衡潮汐、动力潮汐、阻力(摩擦力和引力)以及恒星质量损失的影响下绕其主星运行的轨道演化。我们使用Geneva恒星演化程序计算了初始质量为1和1.5太阳质量的恒星在太阳金属丰度下不同自转速率的演化。这颗恒星是从前主序星(PMS)演化到红巨星分支的尖端。我们使用这些模型作为输入来计算行星轨道的演变。我们探索了改变行星质量(1个地球质量到20个木星质量),行星和恒星之间的距离(0.015和3个天文单位以上),质量和恒星自旋的影响。我们目前的结果时,只有平衡潮汐占平衡和动态潮汐占。动力潮汐的表达式是潮汐激发的惯性波的频率平均耗散,从分段均匀的两层恒星模型获得。忽略了重力波阻尼。对流区的动力潮汐只有在PMS阶段和快速旋转的恒星才对行星轨道产生重大影响。它们在PMS阶段对初始慢转恒星和红巨星分支阶段没有显著影响,无论初始旋转如何(删节)。

英文摘要:

When planets are formed from the protoplanetary disk and after the disk has dissipated, the evolution of their orbits is governed by tidal interactions, friction, and gravitational drag, and also by changes in the mass of the star and planet. These interactions may change the initial distribution of the distances between the planets and their host star by expanding the original orbit, by contracting it (which may cause an engulfment of the planet by the star), or by destroying the planet. We study the evolution of the orbit of a planet orbiting its host star under the effects of equilibrium tides, dynamical tides, drag (frictional and gravitational), and stellar mass loss. We used the Geneva stellar evolution code to compute the evolution of stars with initial masses of 1 and 1.5 solar mass with different rotation rates at solar metallicity. The star is evolved from the pre-main-sequence (PMS) up to the tip of the red giant branch. We used these models as input for computing the evolution of the planetary orbits. We explored the effects of changing the planet masses (of 1 Earth mass up to 20 Jupiter masses), the distance between the planet and the star (of 0.015 and more than 3 au), the mass, and the spin of the star. We present results when only the equilibrium tide was accounted for and when both equilibrium and dynamical tides were accounted for. The expression for the dynamical tide is a frequency-averaged dissipation of tidally excited inertial waves, obtained from a piecewise homogeneous two-layer stellar model. Gravity wave damping was neglected. Dynamical tides in convective zones have a significant effect on planetary orbits only during the PMS phase and only for fast-rotating stars. They have no significant effects during the PMS phase for initially slow-rotating stars and during the red giant branch phase, regardless of the initial rotation (abridged).

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