Hot Jupiters from Coplanar High-eccentricity Migration

Abstract

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 ($\lesssim 20^{\circ }$) 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 $\gtrsim 0.67$ for $m_{\mathrm{in}}/m_{\mathrm{out}}(a_{\mathrm{in}}/a_{\mathrm{out}}{)}^{1/2}\lesssim 0.3$; (ii) two eccentric ($\gtrsim 0.5$) orbits for $m_{\mathrm{in}}/m_{\mathrm{out}}(a_{\mathrm{in}}/a_{\mathrm{out}}{)}^{1/2}\lesssim 0.16$. 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 ($\lesssim 30^{\circ }$), 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 ($a\gtrsim 5$ AU) and massive (most likely $\sim 1-3$ more massive than the hot Jupiter) companions with relatively low mutual inclinations ($\lesssim 20^{\circ }$) and moderately high eccentricities ($e\sim 0.2-0.5$)

17 pages, 9 figures, published in ApJ

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Cited by in corpus (13)

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• Secular chaotic dynamics in hierarchical quadruple systems, with applications to hot Jupiters in stellar binaries and triples
• Eccentricity and Spin-Orbit Misalignment in Short-Period Stellar Binaries as a Signpost of Hidden Tertiary Companions
• Moderately Eccentric Warm Jupiters from Secular Interactions with Exterior Companions
• Chaotic quadruple secular evolution and the production of misaligned exomoons and Warm Jupiters in stellar multiples
• Hot Jupiters driven by high-eccentricity migration in globular clusters
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• Exterior Companions to Hot Jupiters Orbiting Cool Stars are Coplanar
• Hints for hidden planetary companions to hot Jupiters in stellar binaries
• Possible Outcomes of Coplanar High-eccentricity Migration: Hot Jupiters, Close-in Super-Earths, and Counter-orbiting Planets