Are There Moonlets Near the Uranian Α and Β Rings?

Chancia, Robert; Hedman, M. M.

doi:10.3847/0004-6256/152/6/211

Cited by 34 publications

(15 citation statements)

References 29 publications

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“…At λ = 0.2µm, the great distances D of Uranus (19.2 AU) and Neptune (30 AU) from Earth prevent ground-based or Earth-orbit-based stellar occultations from obtaining better resolution than about 750 m and 950 m, respectively. Given that wave-like variations in the dense rings have sub-kilometer wavelengths (Chancia & Hedman 2016;Horn et al 1988), we expect resolutions of order 200 m is needed to see any planetgenerated waves. This resolution threshold, combined with the number of cuts required to uniquely determine the number of arms, which is of order the relevant m (about 20 for the waves of interest here), implies that the detection of planetary normal modes via wave identification will have to await an orbiter of Uranus or Neptune.…”

Section: Occultations Of Narrow Dense Ringsmentioning

confidence: 99%

Ring Seismology of the Ice Giants Uranus and Neptune

A'Hearn¹,

Hedman²,

Mankovich³

et al. 2022

Preprint

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We assess the prospect of using ring seismology to probe the interiors of the ice giants Uranus and Neptune. We do this by calculating normal mode spectra for different interior models of Uranus and Neptune using the stellar oscillation code GYRE. These spectra provide predictions of where in these planets' ring systems the effects of interior oscillations might be detected. We find that f-mode resonances with azimuthal order m = 2 or 7 ≤ m ≤ 19 fall among the inner rings (6, 5, 4, α, and β) of Uranus, while f-mode resonances with 2 ≤ m ≤ 12 fall in the tenuous ζ ring region. In addition, f-mode resonances with m = 2 or 6 ≤ m ≤ 13 may give azimuthal structure to Neptune's tenuous Galle ring. We also find that g-mode resonances may fall in the middle to outer rings of these planets. Although an orbiter is most likely required to confirm the association between any waves in the rings and planetary normal modes, the diversity of normal mode spectra implies that identification of just one or two modes in the rings of Uranus or Neptune would eliminate a variety of interior models, and thus aid in the interpretation of Voyager observations and future spacecraft measurements.

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Section: Occultations Of Narrow Dense Ringsmentioning

confidence: 99%

Ring Seismology of the Ice Giants Uranus and Neptune

A'Hearn¹,

Hedman²,

Mankovich³

et al. 2022

Preprint

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“…The Uranian rings contain abundant km-scale structure, both radial and azimuthal, but much of it is uncharacterized and unexplained 38,39 . Furthermore, the Uranian rings could display oscillations that would allow for investigations of the interior structure of Uranus ('ring seismology'), similar to those that have led to advances in our understanding of the Saturnian interior 40 .…”

Section: Rings and Minor Satellitesmentioning

confidence: 99%

A New Frontiers Class Mission for the Uranian System that Focuses on Moon, Magnetosphere, and Ring Science

Leonard

Elder²,

Nordheim³

et al. 2021

Bulletin of the AAS

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“…Thus, it is quite unlikely there are two or more undiscovered shepherding moons in this size range. Chancia & Hedman [27] have suggested that there might be small moons exterior to the α and β rings, based on wake-like patterns they detected in Voyager radio occultation data. However, their estimates of the moons' diameters, 4–14 km, may be difficult to reconcile with the sensitivity limits.…”

Section: The Main Uranian Rings and Their ‘Shepherding' Moonsmentioning

confidence: 99%

The rings and small moons of Uranus and Neptune

Showalter

2020

Phil. Trans. R. Soc. A.

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All four giant planets are encircled by distinctive systems of rings and small, inner satellites. These all reside within or near their central planet's Roche limit, the rough boundary within which bodies held together by self-gravity will be disrupted by tidal forces. However, the similarities of the four ring-moon systems end here; in most other regards, they are remarkably diverse. We study these systems for three key reasons: (1) for the information they reveal about the properties, history and ongoing evolution of the planetary systems of which they are a part; (2) as dynamical analogues for other astrophysical systems such as protoplanetary disks; and (3) for the wealth of fascinating properties and origin scenarios that make them worthy of study in their own right. The inner Uranus system is characterized by 10 narrow rings, some quite dense, as well as a variety of more tenuous structures. These are accompanied by 13 known moons all orbiting interior to Miranda. Nine of these, Bianca through Perdita, comprise the most densely packed set of moons in the solar system, with orbits so close that their interactions appear to drive chaos over time scales approximately 10 6 years. Neptune has five named rings, all optically thin, interleaved with seven inner moons. The most notable feature is a set of arcs embedded within the Adams ring; two of these arcs have been stable for time scales of decades. This article is part of a discussion meeting issue ‘Future exploration of ice giant systems’.

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Are There Moonlets Near the Uranian Α and Β Rings?

Cited by 34 publications

References 29 publications

Ring Seismology of the Ice Giants Uranus and Neptune

Ring Seismology of the Ice Giants Uranus and Neptune

A New Frontiers Class Mission for the Uranian System that Focuses on Moon, Magnetosphere, and Ring Science

The rings and small moons of Uranus and Neptune

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