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arXiv 1405.0280astro-ph.EP
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恒星双星中由Kozai-Lidov机制引起的稳态行星迁移

Steady-state planet migration by the Kozai-Lidov mechanism in stellar binaries

Cristobal Petrovich

摘要:

我们研究了巨行星的稳态轨道分布迁移通过相结合的Kozai-Lidov(KL)机制,由于恒星的同伴和摩擦,由于潮汐引起的行星上的主恒星。我们运行了大量的蒙特卡罗模拟,描述了恒星-行星-恒星三重系统的长期演化,包括广义相对论进动,恒星和行星自旋演化和潮汐的影响。我们的模拟结果表明,KL迁移产生的热彗星(HJ)的半长轴一般小于观测结果,它们只能解释观测结果,如果以下两个都是真的:(i)在高偏心率潮汐耗散至少是$\sim 150$倍以上的效率比上限推断从彗星-木卫一相互作用;(ii)高度偏心的行星得到潮汐中断距离$\gtrsim 0.015$ AU。根据黑洞的出现率和半长轴分布,我们发现恒星双星中的KL迁移最多能产生观测到的黑洞中的$\sim 20\%$。几乎没有中间周期(半长轴$\sim0.1-2$ AU)行星是由这种机制形成的-迁移行星在大轨道间隔($>2$ AU)或作为热彗星经历KL振荡。

英文摘要:

We study the steady-state orbital distributions of giant planets migrating through the combination of the Kozai-Lidov (KL) mechanism due to a stellar companion and friction due to tides raised on the planet by the host star. We run a large set of Monte Carlo simulations that describe the secular evolution of a star-planet-star triple system including the effects from general relativistic precession, stellar and planetary spin evolution, and tides. Our simulations show that KL migration produces Hot Jupiters (HJs) with semi-major axes that are generally smaller than in the observations and they can only explain the observations if the following are both true: (i) tidal dissipation at high eccentricities is at least $\sim 150$ times more efficient than the upper limit inferred from the Jupiter-Io interaction; (ii) highly eccentric planets get tidally disrupted at distances $\gtrsim 0.015$ AU. Based on the occurrence rate and semi-major axis distribution of HJs, we find that KL migration in stellar binaries can produce at most $\sim 20\%$ of the observed HJs. Almost no intermediate-period (semi-major axis $\sim0.1-2$ AU) planets are formed by this mechanism - migrating planets spend most of their lifetimes undergoing KL oscillations at large orbital separations ($>2$ AU) or as Hot Jupiters.

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