Cassini Discovers a Kinematic Spiral Ring Around Saturn

Charnoz, Sébastien; Porco, C. C.; Déau, E.; Brahic, A.; Spitale, J. N.; Bacques, G.; Baillié, K.

doi:10.1126/science.1119387

Cited by 46 publications

(67 citation statements)

References 16 publications

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“…We think that we solve in the present paper the problem raised in Charnoz et al (2005) that needed Prometheus-sized moons to create jets and spirals. In the vision we propose here, that is basically the same as in Cuzzi and Burns (1988), the F-ring core destroys, feeds, and scatters the surrounding clump (or moonlet) population.…”

Section: Discussionmentioning

confidence: 92%

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Physical collisions of moonlets and clumps with the Saturn's F-ring core

Charnoz

2009

Icarus

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Since 2004, observations of Saturn's F ring have revealed that the ring's core is surrounded by structures with radial scales of hundreds of kilometers, called "spirals" and "jets". Gravitational scattering by nearby moons was suggested as a potential production mechanism; however, it remained doubtful because a population of Prometheus-mass moons is needed and, obviously, such a population does not exist in the F ring region. We investigate here another mechanism: dissipative physical collisions of kilometer-size moonlets (or clumps) with the F-ring core. We show that it is a viable and efficient mechanism for producing spirals and jets, provided that massive moonlets are embedded in the F-ring core and that they are impacted by loose clumps orbiting in the F ring region, which could be consistent with recent data from ISS, VIMS and UVIS. We show also that coefficients of restitution as low as ~0.1 are needed to reproduce the radial extent of spirals and jets, suggesting that collisions are very dissipative in the F ring region. In conclusion, spirals and jets would be the direct manifestation the ongoing collisional activity of the F ring region.Comment: Accepted for publication in ICARUS 17 pages, 6 figures, 1 tabl

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Section: Discussionmentioning

confidence: 92%

“…At the intersection of these spirals with the F-ring core, smaller chaotic structures of scattered material called "jets" are observed Murray et al, 2008). All these structures are bright at high phase angles so may be mainly composed of dust (Showalter et al, 1992;Charnoz et al, 2005). E-mail address: charnoz@cea.fr.…”

Section: Introductionmentioning

confidence: 96%

Physical collisions of moonlets and clumps with the Saturn's F-ring core

Charnoz

2009

Icarus

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“…6 As seen in Figure 21, S6's orbit came within about 1.5 km of the F-ring core, less than its estimated vertical thickness (Bosh et al 2002), in 2005 April. It would be surprising if such an interaction resulted in no observable consequences; indeed, Charnoz et al (2005) suggest that a newly discovered spiral structure observed in the tenuous material surrounding the F ring may be among those consequences. Differential precession of the node would also imply that the orbits of S/2004 S6 and S/2004 S3 must periodically intersect one another.…”

Section: F-ring Objectsmentioning

confidence: 99%

The Orbits of Saturn's Small Satellites Derived from Combined Historic andCassiniImaging Observations

Spitale

Jacobson

Porco

et al. 2006

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We report on the orbits of the small, inner Saturnian satellites, either recovered or newly discovered in recent Cassini imaging observations. The orbits presented here reflect improvements over our previously published values in that the time base of Cassini observations has been extended, and numerical orbital integrations have been performed in those cases in which simple precessing elliptical, inclined orbit solutions were found to be inadequate. Using combined Cassini and Voyager observations, we obtain an eccentricity for Pan 7 times smaller than previously reported because of the predominance of higher quality Cassini data in the fit. The orbit of the small satellite (S/2005 S1 [Daphnis]) discovered by Cassini in the Keeler gap in the outer A ring appears to be circular and coplanar; no external perturbations are apparent. Refined orbits of Atlas, Prometheus, Pandora, Janus, and Epimetheus are based on Cassini , Voyager, Hubble Space Telescope, and Earth-based data and a numerical integration perturbed by all the massive satellites and each other. Atlas is significantly perturbed by Prometheus, and to a lesser extent by Pandora, through high-wavenumber mean-motion resonances. Orbital integrations involving Atlas yield a mass of GM Atlas ¼ (0:44 AE 0:04) ; 10 À3 km 3 s À2, 3 times larger than reported previously (GM is the product of the Newtonian constant of gravitation G and the satellite mass M ). Orbital integrations show that Methone is perturbed by Mimas, Pallene is perturbed by Enceladus, and Polydeuces librates around Dione's L5 point with a period of about 791 days. We report on the nature and orbits of bodies sighted in the F ring, two of which may have persisted for a year or more.

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“…Whenever the organizing periodic orbit closes after more than one full turn of the secondary, the ring displays non-independent multiple components, reflecting the shape of the organizing periodic or quasi-periodic orbit in the rotating frame. Despite the fact that we have considered only planar motion, and that this is again only a qualitative comparison, the generalization of these "higher periodic" orbits to a non-planar case serves as an interpretation of recent observational findings (Charnoz et al 2005). Moreover, preliminary results (L. Benet and O. Merlo in preparation) show that our theory can also yield other observed properties of narrow rings, such as arcs qualitatively similar to those of Neptune (Namouni and Porco 2002).…”

Section: Discussionmentioning

confidence: 52%

Strands and braids in narrow planetary rings: a scattering system approach

Merlo

Benet

2006

Celestial Mech Dyn Astr

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We address the occurrence of narrow planetary rings and some of their structural properties, in particular when the rings are shepherded. We consider the problem as Hamiltonian scattering of a large number of non-interacting massless point particles in an effective potential. Using the existence of stable motion in scattering regions in this set up, we describe a mechanism in phase space for the occurrence of narrow rings and some consequences in their structure. We illustrate our approach with three examples. We find eccentric narrow rings displaying sharp edges, variable width and the appearance of distinct ring components (strands) which are spatially organized and entangled (braids). We discuss the relevance of our approach for narrow planetary rings.

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Cassini Discovers a Kinematic Spiral Ring Around Saturn

Cited by 46 publications

References 16 publications

Physical collisions of moonlets and clumps with the Saturn's F-ring core

Physical collisions of moonlets and clumps with the Saturn's F-ring core

The Orbits of Saturn's Small Satellites Derived from Combined Historic andCassiniImaging Observations

Strands and braids in narrow planetary rings: a scattering system approach

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