Time change for an electron moving in an electric field subject to damping

Safronov, A. N.

doi:10.1007/bf00838583

Cited by 10 publications

(12 citation statements)

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“…Uranus has a tilt of 98 degrees, with an associated ring system, but no consensus of how it ended up with this obliquity. 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: 64%

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: 64%

Constraints on the size and dynamics of the J1407b ring system

Rieder

Kenworthy

2016

A&A

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“…These may have weakened the lithosphere or created fractures/faults that made it more susceptible to the subsequent extension (see also Section 4.2). A later shift in the rotational equator of Charon can be induced by a planetary-scale impact, if the impactor is sufficiently massive (Safronov 1966), leading to the currently observed orientation. This proposed impact may also be supported by several other features and terrains on the surface.…”

Section: Speculation On the Belt's Localization And Orientationmentioning

confidence: 88%

The contraction/expansion history of Charon with implications for its planetary-scale tectonic belt

Malamud

Perets

Schubert

2017

Monthly Notices of the Royal Astronomical Society

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The New Horizons mission to the Kuiper Belt has recently revealed intriguing features on the surface of Charon, including a network of chasmata, cutting across or around a series of high topography features, conjoining to form a belt. It is proposed that this tectonic belt is a consequence of contraction/expansion episodes in the moon's evolution associated particularly with compaction, differentiation and geochemical reactions of the interior. The proposed scenario involves no need for solidification of a vast subsurface ocean and/or a warm initial state. This scenario is based on a new, detailed thermo-physical evolution model of Charon that includes multiple processes. According to the model, Charon experiences two contraction/expansion episodes in its history that may provide the proper environment for the formation of the tectonic belt. This outcome remains qualitatively the same, for several different initial conditions and parameter variations. The precise orientation of Charon's tectonic belt, and the cryovolcanic features observed south of the tectonic belt may have involved a planetary-scale impact, that occurred only after the belt had already formed.

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“…It is possible that the ice giants shared a common formation path while giant impacts (GIs) occurring shortly after their formation have given them their distinct properties (Stevenson 1986;Podolak & Helled 2012). An oblique impact with a massive impactor could not only significantly alter Uranus' spin (Safronov 1966), but could also eject enough material to form a disk where its regular moons are formed. An oblique impact typically does not affect the planetary internal structure, so any composition barrier that inhibits convection is expected to remain.…”

Section: Introductionmentioning

confidence: 99%

Bifurcation in the history of Uranus and Neptune: the role of giant impacts

Reinhardt

Chau

Stadel

et al. 2019

Monthly Notices of the Royal Astronomical Society

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Despite many similarities, there are significant observed differences between Uranus and Neptune: while Uranus is tilted and has a regular set of satellites, suggesting their accretion from a disk, Neptune's moons are irregular and are captured objects. In addition, Neptune seems to have an internal heat source, while Uranus is in equilibrium with solar insulation. Finally, structure models based on gravity data suggest that Uranus is more centrally condensed than Neptune. We perform a large suite of high resolution SPH simulations to investigate whether these differences can be explained by giant impacts. For Uranus, we find that an oblique impact can tilt its spin axis and eject enough material to create a disk where the regular satellites are formed. Some of the disks are massive and extended enough, and consist of enough rocky material to explain the formation of Uranus' regular satellites. For Neptune, we investigate whether a head-on collision could mix the interior, and lead to an adiabatic temperature profile, which may explain its larger flux and higher moment of inertia value. We find that massive and dense projectiles can penetrate towards the centre and deposit mass and energy in the deep interior, leading to a less centrally concentrated interior for Neptune. We conclude that the dichotomy between the ice giants can be explained by violent impacts after their formation.

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Time change for an electron moving in an electric field subject to damping

Cited by 10 publications

References 0 publications

Constraints on the size and dynamics of the J1407b ring system

Constraints on the size and dynamics of the J1407b ring system

The contraction/expansion history of Charon with implications for its planetary-scale tectonic belt

Bifurcation in the history of Uranus and Neptune: the role of giant impacts

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