Explaining why the uranian satellites have equatorial prograde orbits despite the large planetary obliquity

Morbidelli, Alessandro; Tsiganis, Kleomenis; Batygin, Konstantin; Crida, A.; Gomes, Rodney S.

doi:10.1016/j.icarus.2012.03.025

Cited by 96 publications

(113 citation statements)

References 9 publications

(14 reference statements)

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“…Early theories suggested a single giant impactor caused the planet to tilt over (Safronov 1966), and possibly disrupt an initially circular orbit into the elliptical one we hypothesise. More recently, Morbidelli et al (2012) show that a single impactor leads to retrograde motions in the rings and moons, and that a series of smaller impacts can preserve the orbital motion of the rings.…”

Section: Discussionmentioning

confidence: 99%

Constraints on the size and dynamics of the J1407b ring system

Rieder

Kenworthy

2016

A&A

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Context. J1407 (1SWASP J140747.93-394542.6 in full) is a young star in the Scorpius-Centaurus OB association that underwent a series of complex eclipses over 56 days in 2007. To explain these, it was hypothesised that a secondary substellar companion, J1407b, has a giant ring system filling a large fraction of the Hill sphere, causing the eclipses. Observations have not successfully detected J1407b, but do rule out circular orbits for the companion around the primary star. Aims. We test to what degree the ring model of J1407b could survive in an eccentric orbit required to fit the observations. Methods. We run N-body simulations under the AMUSE framework to test the stability of Hill radius-filling systems where the companion is on an eccentric orbit. Results. We strongly rule out prograde ring systems and find that a secondary of 60 to 100M Jup with an 11 year orbital period and retrograde orbiting material can survive for at least 10 4 orbits and produce eclipses with similar durations as the observed one. Conclusions.

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Section: Discussionmentioning

confidence: 99%

Constraints on the size and dynamics of the J1407b ring system

Rieder

Kenworthy

2016

A&A

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“…In other words, we can neglect the back reaction of the changes in the stellar spin axis on the inclination dynamics of the disk. Provided that self-gravity of the disk is typically sufficiently strong to ensure that the disk behaves as an effectively rigid body (see Batygin et al 2011;Morbidelli et al 2012), the extent of warping within the disk should be negligible, and this restricted assumption is likely to be well satisfied for any relevant choice of parameters.…”

Section: Dynamics Of the Stellar Spin Axismentioning

confidence: 99%

Magnetic and Gravitational Disk-Star Interactions: An Interdependence of PMS Stellar Rotation Rates and Spin-Orbit Misalignments

Batygin

Adams

2013

ApJ

113

122

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The presence of giant gaseous planets that reside in close proximity to their host stars, i.e., hot Jupiters, may be a consequence of large-scale radial migration through the protoplanetary nebulae. Within the framework of this picture, significant orbital obliquities characteristic of a substantial fraction of such planets can be attributed to external torques that perturb the natal disks out of alignment with the spin axes of their host stars. Therefore, the acquisition of orbital obliquity likely exhibits sensitive dependence on the physics of disk-star interactions. Here, we analyze the primordial excitation of spin-orbit misalignment of Sun-like stars in light of disk-star angular momentum transfer. We begin by calculating the stellar pre-main-sequence rotational evolution, accounting for spin-up due to gravitational contraction and accretion as well as spin-down due to magnetic star-disk coupling. We devote particular attention to angular momentum transfer by accretion, and show that while generally subdominant to gravitational contraction, this process is largely controlled by the morphology of the stellar magnetic field (that is, specific angular momentum accreted by stars with octupole-dominated surface fields is smaller than that accreted by dipole-dominated stars by an order of magnitude). Subsequently, we examine the secular spin-axis dynamics of diskbearing stars, accounting for the time-evolution of stellar and disk properties, and demonstrate that misalignments are preferentially excited in systems where stellar rotation is not overwhelmingly rapid. Moreover, we show that the excitation of spin-orbit misalignment occurs impulsively through an encounter with a resonance between the stellar precession frequency and the disk-torquing frequency. Cumulatively, the model developed herein opens up a previously unexplored avenue toward understanding star-disk evolution and its consequences in a unified manner.

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“…The origin of Uranus' large obliquity is perhaps one of the most outstanding mysteries of our Solar System. A variety of explanations have been invoked, including a giant impact scenario which may also be implicated in Uranus' low luminosity and small heat flux, and tidal interactions (Boué and Laskar, 2010;Morbidelli et al, 2012). Examining the interior structure and composition of Uranus and its natural satellites, and studying the ring system may allow us to unravel the origin of this Solar System mystery.…”

Section: Scientific Casementioning

confidence: 99%