The two main rings (Le Verrier and Adams) are clearly visible and appear complete over the region imaged. (NASA/Voyager 2, PIA01493)ġ3pcPIA01997.pdf Figure 2: These two 591-second exposures of the rings of Neptune were taken with the clearįilter by the Voyager 2 wide-angle camera on Aug. Indicating that a substantial fraction of the ring optical depth consists of The rings are much brighter in forward scattered light than in backscatter, Using a 111 second exposure with a resolution of 80 km per pixel. (b) This forward scattered light (phase angle 134 ∘) image, FDS 11412.51, was obtained The image appears very noisy because a longĮxposure (111 s) and hard stretch were needed to show the faintly illuminated, low optical depth dark rings of Neptune. The otherīright object in the field is a star. The moon LarissaĪt the top of the image appears streaked as a result of its orbital motion. Image has a unique FDS number), taken in backscattered light (phase angleġ5.5 ∘) with a resolution of 19 km per pixel. This image, FDS 11350.23 (FDS numbers refer to the Voyager flight data system timeline. Optical depth arcs) and Le Verrier, as seen by Voyager 2. Table 2: Neptune’s inner (ring) moons a \figureboxįigure 1: Neptune’s two most prominent rings, Adams (which includes higher a \topruleSatelliteĪ Based on Jacobson and Owen ( 2004) and Jacobson ( 2009) and the physical parameters (radius, albedo) were based on Karkoschka ( 2003). Table 1: Properties of Neptune’s ring system. ( 1995).ī Large particles not detected dust fraction is likely high. \topruleĪ Table from de Pater and Lissauer ( 2015), based on data from Porco et al. Rings, there is a sixth unnamed ring, possibly incomplete, sharing the orbit of the moon Galatea. Within Neptune’s rings (Table 2) these satellites areīelieved to be responsible for much of the radial and longitudinal The Arago ring (the bright outer edge of the Lassell ring), and the The faint Lassell ring (an outward extension of the Le Verrier ring), The rings discovered by Voyager (Figures 2,ģ Table 1) include the relatively bright and narrow Adams and Le Verrier rings, each with an optical depth of order 0.003, Throughout the Voyager era (Hubbard et al., 1986), and well beyond, as The arcs should have been destroyed in a few months time throughĭifferential Keplerian motion, they appeared to persist at least The optical depth in the arcs is of order 0.1. To a longitude range of 40 ∘ they had typical radial widths of ∼ 15 km (Hubbard et al., 1986 Sicardy et al., 1991 Porco et al., 1995). The arcs varied in extentįrom ∼ 1 ∘ to ∼ 10 ∘, and together were confined Four ringĪrcs were identified: the trailing arc Fraternité aĭouble-component arc Egalité, dubbed Egalité 1 and 2 Of the arcs in backscattered and forward scattered light. Within Neptune’s narrow Adams ring, the outermost of six tenuous ringsĭiscovered by Voyager. That the Neptunian arcs are concentrations of particles embedded Years via other occultation experiments (Nicholson et al., 1990, 1995 Sicardy et al., 1991), and by the Voyager 2 TheĮxistence of ring arcs around Neptune was confirmed during subsequent Or ring arc (Hubbard, 1986 Hubbard et al., 1986 Manfroid et al., 1986). Only on ingress, it was attributed to the existence of a partial ring Occultation of a star near Neptune since the occultation was recorded In 1984, three telescopes in South America recorded an
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