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Specific Angular Momentum of Extrasolar Planetary Systems

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Unpublished Paper

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Specific Angular Momentum of Extrasolar Planetary Systems

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Angular momentum in our solar system is largely distributed between the Sun’s rotation and the planetary orbits, with most of it residing in the orbital angular momentum of Jupiter. By treating the solar system as a two body central potential between the Sun and Jupiter, one can show that the orbital specific angular momentum of the two-body system exceeds the solar rotational specific angular momentum by nearly two orders of magnitude. We extend this analysis to the known extrasolar planets available in the Extrasolar Planet Encyclopedia and estimate the partitioning of each system’s angular momentum into orbital and rotational components, ignoring the spin angular momentum of the planets. We find the range of partitioning of specific angular momentum in these systems to be large, with some systems near the stellar rotational limit, and others with orbital specific angular momentum exceeding this limit by three orders of magnitude. Planets in systems with high specific angular momentum have masses greater than two Jupiter masses, while those in systems with low specific angular momentum are below two Jupiter masses. This leads to the conclusion that low mass planets lose angular momentum more efficiently, and are thus more prone to migration, than larger mass planets.



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