The dynamic neptunian ring arcs: evidence for a gradual disappearance of Liberté and resonant jump of courage

Pater, Imke de; Gibbard, S. G.; Chiang, Eugene; Hammel, Heidi B.; Macintosh, Bruce; Marchis, Franck; Martin, S. C.; Roe, H. G.; Showalter, M. R.

doi:10.1016/j.icarus.2004.10.020

Cited by 45 publications

(41 citation statements)

References 22 publications

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“…UsingΩ G = −0.714836 deg day −1 (Owen 1991), n CIR = 820.11760 ± 0.00008 deg day −1 where the uncertainty is caused by that on Galatea's mean motion. This value is similar to the previous arc mean motion measurements Sicardy et al 1999;Dumas et al 1999Dumas et al , 2002de Pater et al 2005), showing that the arcs are not at the location of the 42:43 CIR with Galatea. The drift in mean motion is Δn = n CIR − n ARCS = 5.5 ± 0.1 × 10 −3 deg day −1 , equivalent to a mismatch Δa 300 ± 5 m in semi-major axis, the half-width of the CIR being 250 ± 100 m (Porco 1991;Owen 1991;Foryta & Sicardy 1996).…”

Section: Astrometry and Mean Motionssupporting

confidence: 90%

“…We detected the arcs Fraternité and Egalité, with flux densities and longitudinal extensions similar to those of the previous Keck observations (de Pater et al 2005). Taking into account the small changes in distance and phase angle, the equivalent width of the arc Fraternité is E Fr = 71 ± 10 m compared with ∼65 m in October 2003 (de Pater et al 2005).…”

Section: Photometrysupporting

confidence: 84%

“…Taking into account the small changes in distance and phase angle, the equivalent width of the arc Fraternité is E Fr = 71 ± 10 m compared with ∼65 m in October 2003 (de Pater et al 2005). We note that Egalité is ∼20% fainter than Fraternité in our data.…”

Section: Photometrymentioning

confidence: 47%

“…We note that Egalité is ∼20% fainter than Fraternité in our data. According to de Pater et al (2005), Egalité was 17% brighter than Fraternité in 2002 while its intensity decreased to 7% below that of Fraternité in 2003. Therefore the decrease in intensity might be as high as ∼44% between 2002 and 2007.…”

Section: Photometrymentioning

confidence: 99%

“…The arcs are close to but not within a 42:43 corotation inclination resonance (CIR) forced by Galatea (Dumas et al 1999;Sicardy et al 1999), which was thought to be responsible for the azimuthal confinement of the arc system (Goldreich et al 1986;Porco 1991). Moreover, adaptive-optics images obtained in 2002 and 2003 with the Keck telescope showed that the brightness and longitudes of the arcs changed significantly (de Pater et al 2005). Different theories were able to solve, at least partly, the question of the arcs' stability.…”

Section: Introductionmentioning

confidence: 99%

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Neptune’s ring arcs: VLT/NACO near-infrared observations and a model to explain their stability

Renner

Sicardy

Souami

et al. 2014

A&A

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Context. Neptune's incomplete ring arcs have been stable since their discovery in 1984 although these structures should be destroyed in a few months through differential Keplerian motion. Regular imaging data are needed to address the question of the arc stability. Aims. We present the first NACO observations of Neptune's ring arcs taken at 2.2 μm (Ks band) with the Very Large Telescope in August 2007, and propose a model for the arc stability based on co-orbital motion. Methods. The images were aligned using the ephemerides of the satellites Proteus and Triton and were suitably co-added to enhance ring or satellite signals. Resonance theory and N-body simulations were used to model the arcs' confinement. Results. We derive accurate mean motion values for the arcs and Galatea and confirm the mismatch between the arcs' position and the location of the 42:43 corotation inclination resonance. We propose a new confinement mechanism where small co-orbital satellites in equilibrium trap ring arc material. We constrain the masses and locations of these hypothetical co-orbital bodies.

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