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arXiv 1409.8296astro-ph.EP
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来自共面高偏心率偏移的热中子源

Hot Jupiters from Coplanar High-eccentricity Migration

Cristobal Petrovich

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17 pages, 9 figures, published in ApJ
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摘要：

我们研究的可能性，热彗星是通过两个行星之间的长期引力相互作用，在偏心轨道相对较低的相互倾斜（$\lesssim20^\circ$）和摩擦，由于潮汐提出的行星上的主机恒星。我们称这种迁移机制为共面高偏心率迁移，因为像磁盘迁移一样，它允许迁移发生在行星形成的同一平面上。共面高偏心率迁移可以从以下典型的初始配置操作：（i）在圆形轨道的内行星和外行星与偏心率$\gtrsim0.67$为$m_{\rm in}/m_{\rm out}(a_{\rm in}/a_{\rm out})^{1/2}\lesssim0.3$ ;（ii）两个偏心（$\gtrsim0.5$）轨道为$m_{\rm in}/m_{\rm out}(a_{\rm in}/a_{\rm out})^{1/2}\lesssim0.16$。利用观测到的巨行星偏心率分布对两颗巨行星的等级系统进行的星族合成研究表明，共面高偏心率迁移产生了低恒星偏心率的热彗星（$\lesssim30^\circ$），其半长轴分布与观测结果相匹配，并且其速率可以解释它们的观测发生率。需要一种不同的机制来创造大的热行星，或者是一种不同的迁移通道，或者是一种使恒星或原行星盘倾斜的机制。共面高偏心率迁移预测，热木星应该有远距离（$a\gtrsim5$ AU）和大质量（最有可能$\sim1-3$比热木星更大）的伴星，它们的相互倾角（$\lesssim 20^\circ$）相对较低，偏心率（$e\sim0.2-0.5$）相对较高。

英文摘要：

We study the possibility that hot Jupiters are formed through the secular gravitational interactions between two planets in eccentric orbits with relatively low mutual inclinations ($\lesssim20^\circ$) and friction due to tides raised on the planet by the host star. We term this migration mechanism Coplanar High-eccentricity Migration because, like disk migration, it allows for migration to occur on the same plane in which the planets formed. Coplanar High-eccentricity Migration can operate from the following typical initial configurations: (i) inner planet in a circular orbit and the outer planet with an eccentricity $\gtrsim0.67$ for $m_{\rm in}/m_{\rm out}(a_{\rm in}/a_{\rm out})^{1/2}\lesssim0.3$; (ii) two eccentric ($\gtrsim0.5$) orbits for $m_{\rm in}/m_{\rm out}(a_{\rm in}/a_{\rm out})^{1/2}\lesssim0.16$. A population synthesis study of hierarchical systems of two giant planets using the observed eccentricity distribution of giant planets shows that Coplanar High-eccentricity Migration produces hot Jupiters with low stellar obliquities ($\lesssim30^\circ$), with a semi-major axis distribution that matches the observations, and at a rate that can account for their observed occurrence. A different mechanism is needed to create large obliquity hot Jupiters, either a different migration channel or a mechanism that tilts the star or the proto-planetary disk. Coplanar High-eccentricity Migration predicts that hot Jupiters should have distant ($a\gtrsim5$ AU) and massive (most likely $\sim1-3$ more massive than the hot Jupiter) companions with relatively low mutual inclinations ($\lesssim 20^\circ$) and moderately high eccentricities ($e\sim0.2-0.5$)

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