The Structure of Saturn's Rings

  • J. E. Colwell
  • P. D. Nicholson
  • M. S. Tiscareno
  • C. D. Murray
  • R. G. French
  • E. A. Marouf

Abstract

Our understanding of the structure of Saturn's rings has evolved steadily since their discovery by Galileo Galilei in 1610. With each advance in observations of the rings over the last four centuries, new structure has been revealed, starting with the recognition that the rings are a disk by Huygens in 1656 through discoveries of the broad organization of the main rings and their constituent gaps and ringlets to Cassini observations that indirectly reveal individual clumps of particles tens of meters in size. The variety of structure is as broad as the range in scales. The main rings have distinct characteristics on a spatial scale of 104 km that suggest dramatically different evolution and perhaps even different origins. On smaller scales, the A and C ring and Cassini Division are punctuated by gaps from tens to hundreds of kilometer across, while the B ring is littered with unexplained variations in optical depth on similar scales. Moons are intimately involved with much of the structure in the rings. The outer edges of the A and B rings are shepherded and sculpted by resonances with the Janus—Epimetheus coorbitals and Mimas, respectively. Density waves at the locations of orbital resonances with nearby and embedded moons make up the majority of large-scale features in the A ring. Moons orbiting within the Encke and Keeler gaps in the A ring create those gaps and produce wakes in the nearby ring. Other gaps and wave-like features await explanation. The largest ring particles, while not massive enough to clear a gap, produce localized propeller-shaped disturbances hundreds of meters long. Particles throughout the A and B rings cluster into strands or self-gravity wakes tens of meters across that are in equilibrium between gravitational accretion and Keplerian shear. In the peaks of strong density waves particles pile together in a cosmic traffic jam that results in kilometer-long strands that may be larger versions of self-gravity wakes. The F ring is a showcase of accretion and disruption at the edges of Saturn's Roche zone. Clumps and strands form and are disrupted as they encounter each other and are perturbed by close encounters with nearby Prometheus. The menagerie of structures in the rings reveals a system that is dynamic and evolving on timescales ranging from days to tens or hundreds of millions of years. The architecture of the rings thus provides insight to the origin as well as the long and short-term evolution of the rings.

Keywords

Dust Microwave Torque Attenuation Titan 

Notes

Acknowledgments

This work was carried out with support from the NASA/ESA Cassini-Huygens project. We thank Matt Hedman for assistance with some figures. JEC and MST were also supported by the NASA Cassini Data Analysis Program. CM is grateful to the UK Science and Technology Facilities Council for financial support. The authors would also like to acknowledge the work of their colleagues on the various Cassini science and engineering teams and the dedicated science planning engineers at JPL, without whom none of the Cassini data described herein would exist.

References

  1. Alexander, A. F. O'D. 1962. The Planet Saturn: A History of Observation, Theory, and Discovery. Faber and Faber, London.Google Scholar
  2. Araki, S., Tremaine, S. 1986. The dynamics of dense particle disks. Icarus 65, 83–109.ADSGoogle Scholar
  3. Barbara, J., Esposito, L. W. 2002. Moonlet collisions and the effects of tidally modified accretion in Saturn's F ring. Icarus 160, 161–171.ADSGoogle Scholar
  4. Borderies, N., Goldreich, P. 1983. The variations in eccentricity and apse precession rate of a narrow ring perturbed by a close satellite. Icarus 53, 84–89.ADSGoogle Scholar
  5. Borderies, N., Goldreich, P., Tremaine, S. 1986. Nonlinear density waves in planetary rings. Icarus 68, 522–533.ADSGoogle Scholar
  6. Bosh, A. S., Olkin, C. B., French, R. G., Nicholson, P. D. 2002. Saturn's F ring: Kinematics and particle sizes from stellar occultation studies. Icarus 157, 57–75.ADSGoogle Scholar
  7. Bridges, F., Hatzes, A., Lin, D. 1984. Structure, stability, and evolution of Saturn's Rings. Nature 309, 333–335.ADSGoogle Scholar
  8. Camichel, H., 1958. Mesures photométriques de Saturne et de son an-neau. Ann. d'Astrophys. 21, 231–242.ADSGoogle Scholar
  9. Chakrabarti, S. K. 1989. The dynamics of particles in the bending waves of planetary rings. Mon. Not. Roy. Astron. Soc. 238, 1381–1394.ADSGoogle Scholar
  10. Charnoz, S., Porco, C. C., Déau, E., Brahic, A., Spitale, J. N., Bacques, G., Baillié, K. 2005. Cassini discovers a kinematic spiral ring around Saturn. Science 310, 1300–1304.ADSGoogle Scholar
  11. Colombo, G., Goldreich, P., Harris, A.W. 1976. Spiral structure as an explanation for the asymmetric brightness of Saturn's A ring. Nature 264, 344–345.ADSGoogle Scholar
  12. Colwell, J. E., Esposito, L. W., Sremčević, M. 2005. Cassini UVIS star occultation results for Saturn's rings. American Geophysical Union, Fall Meeting 2005, abstract #P31D-03.Google Scholar
  13. Colwell, J. E., Esposito, L. W., Sremčević, M. 2006. Gravitational wakes in Saturn's A ring measured by stellar occulta-tions from Cassini. Geophys. Res. Lett. 33, L07201, doi:10.1029/ 2005GL025163.Google Scholar
  14. Colwell, J. E., Esposito, L. W., Sremčević, M., Stewart, G. R., McClintock, W. E. 2007. Self-gravity wakes and radial structure of Saturn's B ring. Icarus 190, 127–144, doi:10.1016/ j.icarus.2007.03.018.ADSGoogle Scholar
  15. Colwell, J. E., Cooney, J. H., Esposito, L. W., Sremčević, M. 2009. Density Waves in Cassini UVIS stellar occultations 1. The Cassini Division. Icarus 200, 2, 574–580, doi:10.1016/ j.icarus.2008.12.031.ADSGoogle Scholar
  16. Colwell, J. E., Esposito, L. W., Jerousek, R. G., Lissauer, J. J. 2008.Ver-tical structure of Saturn's rings from Cassini UVIS stellar occulta-tions. 37th COSPAR Scientific Assembly, Montreal.Google Scholar
  17. Cooke, M. L. 1991. Saturn's Rings: Radial Variation in the Keeler Gap and C Ring Photometry. Ph.D. Thesis. Cornell University, Ithaca.Google Scholar
  18. Cuzzi, J. N., Lissauer, J. J., Shu, F. H. 1981. Density waves in Saturn's rings. Nature 292, 703–707.ADSGoogle Scholar
  19. Cuzzi, J. N., 1985. Rings of Uranus: Not so thick, not so black. Icarus 63, 312–316.ADSGoogle Scholar
  20. Cuzzi, J. N., Scargle, J. D. 1985. Wavy edges suggest moonlet in Encke's gap. Astrophys. J. 292, 276–290.ADSGoogle Scholar
  21. Cuzzi, J. N., Burns, J. A. 1988. Charged particle depletion surrounding Saturn's F ring: evidence for a moonlet belt? Icarus 74, 284–324.ADSGoogle Scholar
  22. Cuzzi, J. N., Lissauer, J. J., Esposito, L. W., Holberg, J. B., Marouf, E. A.,Tyler, G. L, Boischot, A. 1984. Saturn's rings: Properties and processes. In Planetary Rings (R. Greenberg and A. Brahic, Eds.) University of Arizona Press, Tucson, pp. 73–199.Google Scholar
  23. Cuzzi, J. N., Clark, R., Filacchione, G., French, R., Johnson, R., Marouf, E., Spilker, L. 2009. Ring particle composition and size distribution. In Saturn After Cassini-Huygens (M. Dougherty, L. Esposito, S. Krimigis, Eds.) Springer.Google Scholar
  24. Dermott, S. F. 1984. In Planetary Rings (R. Greenberg and A. Brahic, Eds.) University of Arizona Press, Tucson, pp. 589–637.Google Scholar
  25. Dones, L., Porco, C. C. 1989. Spiral density wakes in Saturn's A ring? Bull. Am. Astron. Soc. 21, 929.ADSGoogle Scholar
  26. Dones, L., Cuzzi, J.N., Showalter, M.R. 1993. Voyager photometry of Saturn's A ring. Icarus 105, 184–215.ADSGoogle Scholar
  27. Dunn, D. E., Molnar, L. A., Niehof, J. T., de Pater, I., Lissauer, J. J. 2004. Microwave observations of Saturn's rings: anisotropy in directly transmitted and scattered saturnian thermal emission. Icarus 171, 183–198.ADSGoogle Scholar
  28. Dunn, D. E., de Pater, I., Wright, M., Hogerheijde, M. R., Molnar, L. A. 2005. High-quality BIMA-OVRO images of Saturn and its rings at 1.3 and 3 millimeters. Astron. J. 129, 1109–1116.ADSGoogle Scholar
  29. Dunn, D. E., de Pater, I., Molnar, L. A. 2007. Examining the wake structure in Saturn's rings from microwave observations over varying ring opening angles and wavelengths. Icarus, 192, 56–76, doi:10.1016/j.icarus.2007.06.017.ADSGoogle Scholar
  30. Durisen, R. H., Cramer, N. L., Murphy, B. W., Cuzzi, J. N., Mullikin, T. L., Cederbloom, S. E. 1989. Ballistic transport in planetary ring systems due to particle erosion mechanisms. I — Theory, numerical methods, and illustrative examples. Icarus 80, 136–166.ADSGoogle Scholar
  31. Durisen, R. H., Bode, P. W., Cuzzi, J. N., Cederbloom, S. E., Murphy, B. W. 1992. Ballistic transport in planetary ring systems due to particle erosion mechanisms. II. Theoretical models for Saturn's A- and B-Ring inner edges. Icarus 100, 364–393.ADSGoogle Scholar
  32. Esposito, L. W., O'Callaghan, M. West, R. A. 1983a. The structure of Saturn's rings: Implications from the Voyager stellar occultation. Icarus 56, 439–452.ADSGoogle Scholar
  33. Esposito, L. W., Harris, C. C., Simmons, K. E. 1987. Features in Saturn's rings. Astrophys. J. Supp., 63, 749–770.ADSGoogle Scholar
  34. Esposito, L. W., Borderies, N., Goldreich, P., Cuzzi, J. N., Holberg, J. B., Lane, A. L., Pomphrey, R. B., Terrile, R. J., Lissauer, J. J., Marouf, E. A., Tyler, G. L. 1983b. Eccentric ringlet in the Maxwell gap at 1.45 Saturn radii Multi-instrument Voyager observations. Science 222, 57–60.ADSGoogle Scholar
  35. Esposito, L. W., Cuzzi, J. N., Holberg, J. B., Marouf, E. A., Tyler, G. L., Porco, C. C. 1984. Saturn's rings: Structure, dynamics, and particle properties. In Saturn (T. Gehrels and M. Matthews, Eds.) University of Arizona Press, Tucson, pp. 463–545.Google Scholar
  36. Esposito, L. W., Meinke, B. K., Colwell, J. E., Nicholson, P. D., Hedman, M. M. 2008. Moonlets and clumps in Saturn's F ring. Icarus 194, 278–289.ADSGoogle Scholar
  37. Estrada, P. R., Cuzzi, J. N. 1996. Voyager observations of the color of saturn's rings. Icarus 122, 251–272.ADSGoogle Scholar
  38. Ferrin, I. 1975. On the structure of Saturn's rings and the “real” rotational period for the planet. Astrophys. Space Sci. 33, 453–457.ADSGoogle Scholar
  39. Filacchione, G., 28 colleagues. 2007. Saturn's icy satellites investigated by Cassini-VIMS. I. Full-disk properties: 350–5100 nm reflectance spectra and phase curves. Icarus 166, 212–222.Google Scholar
  40. Flynn, B. C., Cuzzi, J. N. 1989. Regular structure in the inner Cassini Division of Saturn's rings. Icarus 82, 180–199.ADSGoogle Scholar
  41. Franklin, F. A., Cook, A. F., Barrey, R. T. F., Roff, C. A., Hunt, G. E., de Rueda, H. B. 1987. Voyager observations of the azimuthal brightness variations in Saturn's rings. Icarus 69, 280–296.ADSGoogle Scholar
  42. French, R. G., Elliot, J. L., French, L. M., Kangas, J. A., Meech, K. J., Ressler, M. E., Buie, M. W., Frogel, J. A., Holberg, J. B., Fuensalida, J. J., Joy, M. 1988. Uranian ring orbits from earth-based and Voyager occultation observations. Icarus 73, 349–378.ADSGoogle Scholar
  43. French, R. G., Nicholson, P. D., Cooke, M. L., Elliot, J. L., Matthews, K., Perković, O., Tollestrup, E., Harvey, P., Chanover, N. J., Clark, M. A., Dunham, E. W., Forrest, W., Harrington, J., Pipher, J., Brahic, A., Grenier, I., Roques, F., Arndt, M. 1993. Geometry of the Saturn system from the 3 July 1989 occultation of 28 Sgr and Voyager observations. Icarus 103, 163–214.ADSGoogle Scholar
  44. French, R. G., Nicholson, P. D. 2000. Saturn's rings II. Particle sizes inferred from stellar occultation data. Icarus 145, 502–523, doi:10.1006/icar.2000.6357.ADSGoogle Scholar
  45. French, R. G., Salo, H., McGhee, C., Dones, L. 2007. HST observations of azimuthal asymmetry in Saturn's rings, Icarus (in press).Google Scholar
  46. Gehrels, T., Baker, L. R., Beshore, E., Blenman, C., Burke, J. J., Castillo, N. D., Dacosta, B., Degewij, J., Doose, L. R., Fountain, J. W., Gotobed, J., Kenknight, C. E., Kingston, R., McLaughlin, G., McMillan, R., Murphy, R., Smith, P. H., Stoll, C. P., Strickland, R. N., Tomasko, M. G., Wijesinghe, M. P., Coffeen, D. L., Esposito, L. W. 1980. Imaging photopolarimeter on Pioneer Saturn. Science 207, 434–439.ADSGoogle Scholar
  47. Gehrels, T., Esposito, L.W. 1981. Pioneer fly-by of Saturn and its rings. Adv. Space Res. 1, 67–71.ADSGoogle Scholar
  48. Gehrels, M., Matthews, M. (Eds.). 1984. Saturn. University of Arizona Press, Tucson.Google Scholar
  49. Giuliatti Winter, S. M. 1994. The dynamics of Saturn's F Ring. Ph.D. Thesis, Queen Mary and Westfield College, University of London.Google Scholar
  50. Giuliatti Winter, S. M., Murray, C. D., Gordon, M. 2000. Perturbations to Saturn's F ring strands at their closest approach to Prometheus. Planet. Space. Sci. 48, 817–827.ADSGoogle Scholar
  51. Goldreich, P., Tremaine, S. 1978a. The velocity dispersion in Saturn's rings. Icarus 34, 227–239.ADSGoogle Scholar
  52. Goldreich, P., Tremaine, S. 1978b. The formation of the Cassini division in Saturn's rings. Icarus 34, 240–253.ADSGoogle Scholar
  53. Goldreich, P., Tremaine, S. 1980. Disk—satellite interactions. Astrophys. J. 241, 425–441.MathSciNetADSGoogle Scholar
  54. Goldreich, P., Tremaine, S. 1982. The dynamics of planetary rings. Ann. Rev. Astron. Astrophys. 20, 249–283.ADSGoogle Scholar
  55. Goldreich, P., Tremaine, S. 1979. Precession of the epsilon ring of Uranus. Astron. J. 84, 1638–1641.ADSGoogle Scholar
  56. Goldreich, P., Tremaine, S. 1981. The origin of the eccentricities of the rings of Uranus. Astrophys. J. 243, 1062–1075.MathSciNetADSGoogle Scholar
  57. Greenberg, R., Brahic, A. (Eds.). 1984. Planetary Rings. University of Arizona Press, Tucson.Google Scholar
  58. Harrington, J. Cooke, M. L., Forrest, W. J., Pipher, J. L., Dunham, E. W., Elliot, J. L. 1993. IRTF observations of the occultation of 28 SGR by Saturn. Icarus 103, 235–252, doi:10.1006/icar.1993.1068.ADSGoogle Scholar
  59. Hedman, M. M., Nicholson, P. D., Salo, H., Wallis, B. D., Buratti, B. J., Baines, K. H., Brown, R. H., Clark, R. N. 2007. Self-gravity wake structures in Saturn's A ring revealed by Cassini-VIMS. Astron. J. 133 (6), 2624–2629.ADSGoogle Scholar
  60. Holberg, J. B., Forrester, W. T., Lissauer, J. J. 1982. Identification of resonance features within the rings of Saturn. Nature 297, 115–120.ADSGoogle Scholar
  61. Horányi, M., Burns, J. A., Hedman, M. M., Jones, G. H., Kempf, S. 2009. Diffuse rings. In Saturn After Cassini-Huygens (M. Dougherty, L. Esposito, and S. Krimigis, Eds.) Springer.Google Scholar
  62. Horn, L. J., Cuzzi, J. N. 1996. Characteristic wavelengths of irregular structure in Saturn's B ring. Icarus 119, 285–310.ADSGoogle Scholar
  63. Hubbard, W. B., Porco, C. C., Hunten, D. M., Rieke, G. H., Rieke, M. J., McCarthy, D. W., Haemmerle, V., Clark, R., Turtle, E. P., Haller, J., McLeod, B., Lebofsky, L. A., Marcialis, R., Holberg, J. B., Landau, R., Carrasco, L., Elias, J., Buie, M. W., Persson, S. E., Boroson, T., West, S., Mink, D. J. 1993. The occultation of 28 Sgr by Saturn — Saturn pole position and astrometry. Icarus 103, 215–234.ADSGoogle Scholar
  64. Jacobson, R. A. et al. 2008. Revised orbits of Saturn's small inner satellites. Astron. J. 135, 261–263.ADSGoogle Scholar
  65. Julian, W. H., Toomre, A. 1966. Non-axisymmetric responses of differentially rotating disks of stars. Astrophys. J. 146, 810–830.ADSGoogle Scholar
  66. Kirkwood, D. 1866. On the theory of meteors. Proc. Amer. Assoc. Adv. Sci. 15, 8–14.Google Scholar
  67. Kliore, A. J., Patel, I. R., Lindal, G. F., Sweetnam, D. N., Hotz, H. B., Waite, J. H., McDonough, T. 1980. Structure of the ionosphere and atmosphere of Saturn from Pioneer 11 Saturn radio occultation. J. Geophys. Res. 85, 5857–5870.ADSGoogle Scholar
  68. Kolvoord, R. A., Burns, J. A., Showalter, M. R. 1990. Periodic features in Saturn's F ring. Nature 345, 695–697.ADSGoogle Scholar
  69. Lane, A. L., Hord, C. W., West, R. A., Esposito, L. W., Coffeen, D. L., Sato, M., Simmons, K. E., Pomphrey, R. B., Morris, R. B. 1982. Photopolarimetry from Voyager 2 — Preliminary results on Saturn, Titan, and the rings. Science 215, 537–543.ADSGoogle Scholar
  70. Lewis, M. C., Stewart, G. R. 2005. Expectations for Cassini observations of ring material with nearby moons. Icarus 178, 124–143.ADSGoogle Scholar
  71. Lewis, M. C., Stewart, G. R. 2006. Simulating the Keeler gap in Saturn's rings: Wake and edge dynamics. 38th Meeting of the Division of Planetary Sciences of the American Astronomical Society, abstract 42.05.Google Scholar
  72. Leyrat, C. et al. 2008. Poster presented at the Saturn After Cassini-Huygens Symposium, London, July 28—Aug. 1.Google Scholar
  73. Lin, C. C., Shu, F. H. 1964. On the spiral structure of disk galaxies. Astrophys. J. 140, 646–655.MathSciNetADSGoogle Scholar
  74. Lissauer, J. J. 1985. Bending waves and the structure of Saturn's rings. Icarus 62, 433–447.ADSGoogle Scholar
  75. Lissauer, J. J., Shu, F. H., Cuzzi, J. N. 1984. Viscosity in Saturn's rings. In Planetary Rings, Proceedings of IAU Symposium No. 75, (A. Brahic, Ed.), Toulouse, France, pp. 385–392.Google Scholar
  76. Lissauer, J. J., Goldreich, P., Tremaine, S. 1985. Evolution of the Janus— Epimetheus coorbital resonance due to torques from Saturn's rings. Icarus 64, 425–434.ADSGoogle Scholar
  77. Longaretti, P.-Y., Borderies, N. 1986. Nonlinear study of the Mimas 5:3 density wave. Icarus 67, 211–223.ADSGoogle Scholar
  78. Lumme, K., and Irvine, W.M., 1976. Azimuthal brightness variations of Saturn's rings. Astrophys. J. 204, L55–L57.ADSGoogle Scholar
  79. Lumme, K., Esposito, L.W., Irvine, W.M., and Baum, W.A., 1977. Azimuthal brightness variations of Saturn's rings. II. Observations at an intermediate tilt angle. Astrophys. J. 216, L123–L126.ADSGoogle Scholar
  80. Marley, M. S., Porco, C. C. 1993. Planetary acoustic mode seismology — Saturn's rings. Icarus 106, 508.ADSGoogle Scholar
  81. Marouf, E. A., Tyler, G. L., Rosen, P. A. 1986. Profiling Saturn's rings by radio occultation. Icarus 68, 120–166.ADSGoogle Scholar
  82. Marouf, E. A., Tyler, G. L. 1986. Detection of two satellites in the Cassini division of Saturn's rings. Nature 323, 31–35.ADSGoogle Scholar
  83. Marouf, E. A., French, R. G., Rappaport, N. J., McGhee, C. A., Wong, K., Thomson, F. S., Anabtawi, A. 2006. Structure and properties of Saturn's Ring B from Cassini radio occultations. Bull. Am. Astron. Soc. 38, 552.ADSGoogle Scholar
  84. Maxwell, J. C. 1859. On the stability of Saturn's rings (London). Reprinted in The Scientific Papers of James Clerke Maxwell, 2 Vols. 1890. University of Cambridge Press, Cambridge, pp. 288–374Google Scholar
  85. McGhee, C. A., Nicholson, P. D., French, R. G., Hall, K. J. 2001. HST observations of Saturnian satellites during the 1995 ring plane crossings. Icarus 152, 282–315, doi:10.1006/icar.2001.6635.ADSGoogle Scholar
  86. Molnar, L. A., Dunn, D. E. 1995. The Mimas 2:1 eccentric corotational resonance in Saturn's outer B ring. Icarus 116, 397–408.ADSGoogle Scholar
  87. Molnar, L. A., Dunn, D. E., Niehof, J. T. 1999. Fall 1998 radio observations of Saturn's rings: New evidence of ring wakes. 31st Meeting of the Division of Planetary Sciences of the American Astronomical Society, abstract 44.05.Google Scholar
  88. Murray, C. D., Dermott, S. F. 1999. Solar System Dynamics. Cambridge University Press, Cambridge.MATHGoogle Scholar
  89. Murray, C. D., Chavez, C., Beurle, K., Cooper, N., Evans, M. W., Burns, J. A., Porco, C. C. 2005. How Prometheus creates structure in Saturn's F ring. Nature 437, 1326–1329.ADSGoogle Scholar
  90. Murray, C. D., Beurle, K., Cooper, N. J., Evans, M. W., Williams, G., Charnoz, S. 2008. The determination of the structure of Saturn's F ring by nearby moonlets. Nature 453, 739–744.ADSGoogle Scholar
  91. Nicholson, P. D., Porco, C. C. 1988. A new constraint on Saturn's zonal gravity harmonics from Voyager observations of an eccentric ringlet. J. Geophys. Res. 93, 10209–10224.ADSGoogle Scholar
  92. Nicholson, P. D., Cooke, M. L., Pelton, E. 1990. An absolute radius scale for Saturn's rings. Astron. J. 100, 1339–1362.ADSGoogle Scholar
  93. Nicholson, P. D., Showalter, M. R., Dones, L., French, R. G., Larson, S. M., Lissauer, J. J., McGhee, C. A., Seitzer, P., Sicardy, B., Daniel-son, G. E. 1996. Observations of Saturn's ring-plane crossings in August and November 1995. Science 272, 509–515.ADSGoogle Scholar
  94. Nicholson, P. D., French, R. G., Tollestrup, E., Cuzzi, J. N., Harrington, J., Matthews, K., Perković, O., Stover, R. J. 2000. Saturn's rings I. Optical depth profiles from the 28 Sgr occultation. Icarus 145, 473–500.ADSGoogle Scholar
  95. Nicholson, P. D., French, R. G., Campbell, D. B., Margot, J.-L., Nolan, M. C., Black, G. J., Salo, H. J. 2005. Radar imaging of Saturn's rings. Icarus 177, 32–62.ADSGoogle Scholar
  96. Nicholson, P. D., Hedman, M. M., Clark, R. N., Brown, R. H., Buratti, B. J., Baines, K. H., Cassini VIMS Team 2007. Through a glass darkly: Saturn's enigmatic B ring. 39th Meeting of the Division of Planetary Sciences of the American Astronomical Society, abstract 7.04, Bull. Am. Astron. Soc. 39, 420.Google Scholar
  97. Nicholson, P. D., Hedman, M. M., Clark, R. N., Showalter, M. R., Cruikshank, D. P., Cuzzi, J. N., Filacchione, G., Capaccioni, F., Cerroni, P., Hansen, G. B., Sicardy, B., Drossart, P., Brown, R. H., Buratti, B. J., Baines, K. H., Coradini, A. 2008a. A close look at Saturn's rings with Cassini VIMS. Icarus 193, 182–212.ADSGoogle Scholar
  98. Nicholson, P. D., Hedman, M. M., Salo, H. J., Cassini VIMS Team 2008b. Cassini-VIMS observations of self-gravity wakes in Saturn's rings — II. 39th Meeting of Division of Dynamical Astronomy of the American Astronomical Society, abstract 18.01.Google Scholar
  99. Nicholson, P. D., Hedman, M. M. 2009. Icarus (submitted).Google Scholar
  100. Osterbrook, D. E., Cruikshank, D. P. 1983. J. E. Keeler's discovery of a gap in the outer part of the A ring. Icarus 53, 165–173.ADSGoogle Scholar
  101. Perrine, R. P., Richardson, D. C. 2006. A computational model of moons in planetary ring gaps. 38th Meeting of the Division of Planetary Sciences of the American Astronomical Society, abstract 42.04.Google Scholar
  102. Perrine, R. P., Richardson, D. C. 2007. Numerical studies of satellite-ring interactions. 39th Meeting of the Division of Planetary Sciences of the American Astronomical Society, abstract 10.01.Google Scholar
  103. Porco, C. C. 1983. Voyager Observations of Saturn's Rings. 1: The Eccentric Rings at 1.29, 1.45, 1.95 and 2.27 RS. Ph.D. Thesis. California Institute of Technology, Pasadena.Google Scholar
  104. Porco, C., Nicholson, P. D., Borderies, N., Danielson, G. E., Goldreich, P., Holberg, J. B., Lane, A. L. 1984a. The eccentric Saturnian ringlets at 1.29 R S and 1.45 R S. Icarus 60, 1–16.ADSGoogle Scholar
  105. Porco, C., Danielson, G. E., Goldreich, P., Holberg, J. B., Lane, A. L. 1984b. Saturn's nonaxisymmetric ring edges at 1.95 R S and 2.27 R S. Icarus 60, 17–28.ADSGoogle Scholar
  106. Porco, C. C., Nicholson, P. D. 1987. Eccentric features in Saturn's outer C ring. Icarus 72, 437–467.ADSGoogle Scholar
  107. Porco, C. C., Baker, E., Barbara, J., Beurle, K., Brahic, A., Burns, J. A., Charnoz, S., Cooper, N., Dawson, D. D., Del Genio, A. D., Denk, T., Dones, L., Dyudina, U., Evans, M. W., Giese, B., Grazier, K., Helfenstein, P., Ingersoll, A. P., Jacobson, R. A., Johnson, T. V., McEwen, A., Murray, C. D., Neukum, G., Owen, W. M., Perry, J., Roatsch, T., Spitale, J., Squyres, S., Thomas, P., Tiscareno, M., Turtle, E., Vasavada, A. R., Veverka, J., Wagner, R., West, R. 2005. Cassini imaging science: Initial results on Saturn's rings and small satellites. Science 307, 1226–1236.ADSGoogle Scholar
  108. Porco, C. C., Weiss, J. W., Richard, D. C., Dones, L., Quinn, T., Throop, H. 2008. Simulations of the dynamical and light-scattering behavior of Saturn's rings and the derivation of ring particle and disk properties. Astron. J. 136, 2172–2200.ADSGoogle Scholar
  109. Rappaport N. J., Longaretti, P.-Y., French, R. G., Marouf, E. A., McGhee, C. A. 2008. A procedure to analyze nonlinear density waves in Saturn's rings using several occultation profiles, Icarus (in press).Google Scholar
  110. Reitsema, H.J., Beebe, R.F., Smith, B.A., 1976. Azimuthal brightness variations in Saturn's rings. Astron. J. 81, 209–215.ADSGoogle Scholar
  111. Richardson, D. 1994. Tree code simulations of planetary rings. Mon. Not. Roy. Astron. Soc. 269, 493–511.ADSGoogle Scholar
  112. Rosen, P. A., Lissauer, J. J. 1988. The Titan — 1:0 nodal bending wave in Saturn's ring C. Science 241, 690–694.ADSGoogle Scholar
  113. Rosen, P. A., Tyler, G. L., Marouf, E. A. 1991a. Resonance structures in Saturn's rings probed by radio occultation. I. Methods and examples. Icarus 93, 3–24.ADSGoogle Scholar
  114. Rosen, P. A., Tyler, G. L., Marouf, E. A., Lissauer, J. J. 1991b. Resonance structures in Saturn's rings probed by radio occultation. II — Results and interpretation. Icarus 93, 25–44.ADSGoogle Scholar
  115. Salo, H. 1992. Gravitational wakes in Saturn's rings. Nature 359, 619–621.ADSGoogle Scholar
  116. Salo, H. 1995. Simulations of dense planetary rings. III. Self-gravitating identical particles. Icarus 117, 287–312.ADSGoogle Scholar
  117. Salo, H., Schmidt, J., Spahn, F. 2001. Viscous overstability in Saturn's B ring: I. Direct simulations and measurement of transport coefficients. Icarus 153, 295–315.ADSGoogle Scholar
  118. Salo, H., Karjalainen, R. 2003. Photometric modeling of Saturn's rings. I Monte Carlo method and the effect of nonzero volume filling factor. Icarus 164, 428–460.ADSGoogle Scholar
  119. Salo, H., Karjalainen, R., French, R. G. 2004. Photometric modeling of Saturn's rings. II Azimuthal asymmetry in reflected and transmitted light. Icarus 170, 70–90.ADSGoogle Scholar
  120. Salo, H., French, R. G., Nicholson, P. D., Hedman, M. M., Colwell, J. E., Schmidt, J. 2008. Modeling self-gravity wakes in Saturn's rings: slab models vs. N-body wakes. Saturn After Cassini-Huygens, Imperial College London, August 2008.Google Scholar
  121. Schmidt, J., Salo, H., Spahn, F., Petzschmann, O. 2001. Viscous oversta-bility in Saturn's B-Ring. II. Hydrodynamic theory and comparison to simulations. Icarus 153, 316–331.ADSGoogle Scholar
  122. Schmidt, J., Ohtsuki, K., Rappaport, N., Salo, H., Spahn, F. 2009. Dynamics of Saturn's dense rings. In Saturn After Cassini—Huygens (M. Dougherty, L. Esposito, S. Krimigis, Eds.) Springer.Google Scholar
  123. Schmit, U., Tscharnuter, W. M. 1999. On the formation of the fine-scale structure in Saturn's B ring. Icarus 138, 173–187.ADSGoogle Scholar
  124. Seiß, M., Spahn, F., Sremčević, M., Salo, H. 2005. Structures induced by small moonlets in Saturn's rings: Implications for the Cassini mission. Geophys. Res. Lett. 32, L11205.ADSGoogle Scholar
  125. Showalter, M. R., Burns, J. A. 1982. A numerical study of Saturn's F ring. Icarus 52, 526–544.ADSGoogle Scholar
  126. Showalter, M. R. 1991. Visual detection of 1981S13, Saturn's eighteenth satellite, and its role in the Encke gap. Nature 351, 709–713.ADSGoogle Scholar
  127. Showalter, M. R., Cuzzi, J. N., Marouf, E. A., Esposito, L. W. 1986. Satellite “wakes” and the orbit of the Encke Gap moonlet. Icarus 66, 297–323.ADSGoogle Scholar
  128. Shu, F. H., Cuzzi, J. N., Lissauer, J. J. 1983. Bending waves in Saturn's rings. Icarus 53, 185–206.ADSGoogle Scholar
  129. Shu F. H. 1984. Waves in planetary rings. In Planetary Rings (R. Greenberg and A. Brahic, Eds.), University of Arizona Press, Tucson, pp. 513–561.Google Scholar
  130. Shu, F. H., Dones, L., Lissaur, J. J., Yuan, C., Cuzzi, J. N. 1985. Nonlinear spiral density waves: Viscous damping. Astrophys. J. 299, 542–573.ADSGoogle Scholar
  131. Smith, B. A., Soderblom, L., Beebe, R. F., Boyce, J. M., Briggs, G., Bunker, A., Collins, S. A., Hansen, C., Johnson, T. V., Mitchell, J. L., Terrile, R. J., Carr, M. H., Cook, A. F., Cuzzi, J. N., Pollack, J. B., Danielson, G. E., Ingersoll, A. P., Davies, M. E., Hunt, G. E., Masursky, H., Shoemaker, E. M., Morrison, D., Owen, T., Sagan, C., Veverka, J., Strom, R., Suomi, V. E. 1981. Encounter with Saturn: Voyager 1 imaging science results. Science 212, 163–191.ADSGoogle Scholar
  132. Smith, B. A., Soderblom, L., Batson, R., Bridges, P., Inge, J., Masursky, H., Shoemaker, E., Beebe, R., Boyce, J., Briggs, G., Bunker, A., Collins, S. A., Hansen, C. J., Johnson, T. V., Mitchell, J. L., Terrile, R. J., Cook, A. F., Cuzzi, J., Pollack, J. B., Danielson, G. E., Inger-soll, A., Davies, M. E., Hunt, G. E., Morrison, D., Owen, T., Sagan, C., Veverka, J., Strom, R., Suomi, V. E. 1982. A new look at the Saturn system: The Voyager 2 images. Science 215, 504–537.ADSGoogle Scholar
  133. Spahn, F., Sremčević, M. 2000. Density patterns induced by small moonlets in Saturn's rings? Astron. Astrophys. 358, 368–372.Google Scholar
  134. Spilker, L. J., Pilorz, S., Lane, A. L., Nelson, R. M., Pollard, B., Russell, C. T. 2004. Saturn A ring surface mass densities from spiral density wave dispersion behavior. Icarus 171, 372–390.ADSGoogle Scholar
  135. Spitale, J. N., Jacobson, R. A., Porco, C. C., Owen, W. M. Jr. 2006. The orbits of Saturn's small satellites derived from combined historic and Cassini imaging observations. Astron. J. 132, 692–710.ADSGoogle Scholar
  136. Spitale, J. N., Porco, C. C., Colwell, J. E., Hahn, J. M. 2008a. Kinematics of the outer edges of Saturn's A and B rings. AAS/Division of Dynamical Astronomy Meeting 39, #18.03.Google Scholar
  137. Spitale, J. N., Porco, C. C., Colwell, J. E. 2008b. An inclined Satur-nian ringlet at 1.954 RS. 40th Meeting of the Division of Planetary Sciences of the American Astronomical Society.Google Scholar
  138. Sremčević, M., Spahn, F., Duschl, W. J. 2002. Density structures in perturbed thin cold discs. Mon. Not. Roy. Astron. Soc. 337, 1139–1152, doi:10.1046/j.1365–8711.2002.06011.x.ADSGoogle Scholar
  139. Sremčević, M., Esposito, L. W., Colwell, J. E. 2006. Size of Particles and clumps in Saturnian rings inferred from Cassini UVIS occulta-tions. AAS/Division of Planetary Sciences Meeting 38, #42.17.Google Scholar
  140. Sremčević, M., Schmidt, J., Salo, H., Seiss, M., Spahn, F., Albers, N. 2007. A belt of moonlets in Saturn's A ring. Nature 449, 1019–1021, doi:10.1038/nature06224.ADSGoogle Scholar
  141. Sremčević, M., Stewart, G. R., Albers, N., Colwell, J. E., Esposito, L. W. 2008. Density waves in Saturn's rings: Non-linear dispersion and moon libration effects. AAS/Division of Planetary Sciences Meeting 40, #24.03.Google Scholar
  142. Stewart, G. R., Robbins, S. J., Colwell, J. E. 2007. Evidence for a Primordial Origin of Saturn's Rings. 39th meeting of the Division of Planetary Sciences of the American Astronomical Society, abstract 7.06.Google Scholar
  143. Supulver, K., Bridges, F., Lin, D. 1995. The coefficient of restitution of ice particles in glancing collisions: Experimental results for un-frosted surfaces. Icarus 113, 188–199.ADSGoogle Scholar
  144. Thompson, W.T., Lumme, K., Irvine, W.M., Baum, W.A., Esposito, L.W. 1981. Saturn's rings — azimuthal variations, phase curves, and radial profiles in four colors. Icarus 46, 187–200.ADSGoogle Scholar
  145. Thomson, F. S., Marouf, E. A., Tyler, G. L., French, R. G., Rappaport, N. J. 2007. Periodic microstructure in Saturn's rings A and B. Geo-phys. Res. Lett. 34, L24203, doi:10.1029/2007GL032526.ADSGoogle Scholar
  146. Tiscareno, M. S., Burns, J. A., Hedman, M. M., Spitale, J. N., Porco, C. C., Murray, C. D., Cassini Imaging Team 2005. Wave edges and other disturbances in Saturn's Encke and Keeler gaps. 37th Meeting of the Division of Planetary Sciences of the American Astronomical Society, abstract 64.02.Google Scholar
  147. Tiscareno, M. S., Burns, J. A., Hedman, M. M., Porco, C. C., Weiss, J. W., Dones, L., Richardson, D. C., Murray, C. D. 2006a. 100-metre-diameter moonlets in Saturn's A ring from observations of ‘propeller’ structures. Nature 440, 648–650, doi:10.1038/nature04581.ADSGoogle Scholar
  148. Tiscareno, M. S., Nicholson, P. D., Burns, J. A., Hedman, M. M., Porco, C. C. 2006b. Unravelling temporal variability in Saturn's spiral density waves: Results and predictions. Astrophys. J. 651, L65–L68.ADSGoogle Scholar
  149. Tiscareno, M. S., Burns, J. A., Nicholson, P. D., Hedman, M. M., Porco, C. C. 2007. Cassini imaging of Saturn's rings II. A wavelet technique for analysis of density waves and other radial structure in the rings. Icarus 189, 14–34.ADSGoogle Scholar
  150. Tiscareno, M. S., Burns, J. A., Hedman, M. M., Porco, C. C. 2008. The population of propellers in Saturn's A ring. Astron J. 135, 1083–1091.ADSGoogle Scholar
  151. Toomre, A., 1964. On the gravitational stability of a disk of stars. As-trophys. J. 139, 1217–1238.ADSGoogle Scholar
  152. Torrey, P. A., Tiscareno, M. S., Burns, J. A., Porco, C. C. 2008. Mapping complexity: the wavy edges of the Encke and Keeler gaps in Saturn's rings. AAS/Division of Dynamical Astronomy Meeting Abstracts, 39, abstract 15.19.Google Scholar
  153. Tremaine, S. 2003. On the origin of irregular structure in Saturn's rings. Astron. J. 125, 894–901.ADSGoogle Scholar
  154. Turtle, E., Porco, C., Haemmerle, V., Hubbard, W., Clark, R. 1991. The kinematics of eccentric features in Saturn's Cassini Division from combined Voyager and ground-based data. Bull. Am. Astron. Soc. 23, 1179.ADSGoogle Scholar
  155. Tyler, G. L., Marouf, E. A., Simpson, R. A., Zebker, H. A., Eshleman, V. R. 1983. The microwave opacity of Saturn's rings at wavelengths of 3.6 and 13 cm from Voyager 1 radio occultation. Icarus 54, 160–188.ADSGoogle Scholar
  156. Van Helden, A. 1984. Saturn through the telescope: A brief historical survey. In Saturn (T. Gehrels and J. S. Matthews, Eds.) University of Arizona Press, Tucson, pp. 23–43.Google Scholar
  157. Ward, W. R. 1981. On the radial structure of Saturn's rings. Geophys. Res. Lett. 8, 641–643.ADSGoogle Scholar
  158. Weiss, J. W., Porco, C. C., Tiscareno, M. S. 2008. Edge-waves in ring gaps and the determination of masses of embedded satellites. AAS/Division of Dynamical Astronomy Meeting Abstracts, 39, abstract 18.02.Google Scholar
  159. Wisdom, J., Tremaine, S. 1988. Local simulations of planetary rings. Astron. J. 95, 925–940.ADSGoogle Scholar

Copyright information

© Springer Science+Business Media B.V. 2009

Authors and Affiliations

  • J. E. Colwell
    • 1
  • P. D. Nicholson
    • 2
  • M. S. Tiscareno
    • 2
  • C. D. Murray
    • 3
  • R. G. French
    • 4
  • E. A. Marouf
    • 5
  1. 1.Department of PhysicsUniversity of Central FloridaOrlandoUSA
  2. 2.Department of AstronomyCornell UniversityIthacaUSA
  3. 3.Astronomy Unit, Queen MaryUniversity of LondonLondonUK
  4. 4.Department of AstronomyWellesley CollegeWellesleyUSA
  5. 5.Department of Electrical EngineeringSan Jose State UniversitySan JoseUSA

Personalised recommendations