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Tiscareno MS, Nicholson PD, Cuzzi JN, Spilker LJ, Murray CD, Hedman MM, Colwell JE, Burns JA, Brooks SM, Clark RN, Cooper NJ, Deau E, Ferrari C, Filacchione G, Jerousek RG, Le Mouélic S, Morishima R, Pilorz S, Rodriguez S, Showalter MR, Badman SV, Baker EJ, Buratti BJ, Baines KH, Sotin C. Close-range remote sensing of Saturn's rings during Cassini's ring-grazing orbits and Grand Finale. Science 2019; 364:364/6445/eaau1017. [PMID: 31196983 DOI: 10.1126/science.aau1017] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Accepted: 05/07/2019] [Indexed: 11/02/2022]
Abstract
Saturn's rings are an accessible exemplar of an astrophysical disk, tracing the Saturn system's dynamical processes and history. We present close-range remote-sensing observations of the main rings from the Cassini spacecraft. We find detailed sculpting of the rings by embedded masses, and banded texture belts throughout the rings. Saturn-orbiting streams of material impact the F ring. There are fine-scaled correlations among optical depth, spectral properties, and temperature in the B ring, but anticorrelations within strong density waves in the A ring. There is no spectral distinction between plateaux and the rest of the C ring, whereas the region outward of the Keeler gap is spectrally distinct from nearby regions. These results likely indicate that radial stratification of particle physical properties, rather than compositional differences, is responsible for producing these ring structures.
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Affiliation(s)
- Matthew S Tiscareno
- Carl Sagan Center for the Study of Life in the Universe, SETI Institute, Mountain View, CA 94043, USA.
| | | | | | - Linda J Spilker
- NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
| | - Carl D Murray
- Astronomy Unit, Queen Mary University of London, London E1 4NS, UK
| | - Matthew M Hedman
- Department of Physics, University of Idaho, Moscow, ID 83844, USA
| | - Joshua E Colwell
- Department of Physics, University of Central Florida, Orlando, FL 32816, USA
| | - Joseph A Burns
- Department of Astronomy, Cornell University, Ithaca, NY 14853, USA.,College of Engineering, Cornell University, Ithaca, NY 14853, USA
| | - Shawn M Brooks
- NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
| | | | | | - Estelle Deau
- NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA.,Department of Earth, Planetary, and Space Sciences, University of California at Los Angeles, Los Angeles, CA 90095, USA
| | - Cecile Ferrari
- Institut de Physique du Globe de Paris, Centre National de la Recherche Scientifique (CNRS)-Unité Mixte de Recherche (UMR) 7154, Université Paris-Diderot, Université Sorbonne-Paris-Cité (USPC), Paris, France
| | - Gianrico Filacchione
- INAF-IAPS (Istituto Nazionale di AstroFisica-Istituto di Astrofisica e Planetologia Spaziali), Rome, Italy
| | - Richard G Jerousek
- Department of Physics, University of Central Florida, Orlando, FL 32816, USA
| | - Stéphane Le Mouélic
- Laboratoire de Planetologie et Geodynamique, CNRS-UMR 6112, Université de Nantes, 44322 Nantes, France
| | - Ryuji Morishima
- NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA.,Department of Earth, Planetary, and Space Sciences, University of California at Los Angeles, Los Angeles, CA 90095, USA
| | - Stu Pilorz
- Carl Sagan Center for the Study of Life in the Universe, SETI Institute, Mountain View, CA 94043, USA
| | - Sébastien Rodriguez
- Institut de Physique du Globe de Paris, Centre National de la Recherche Scientifique (CNRS)-Unité Mixte de Recherche (UMR) 7154, Université Paris-Diderot, Université Sorbonne-Paris-Cité (USPC), Paris, France
| | - Mark R Showalter
- Carl Sagan Center for the Study of Life in the Universe, SETI Institute, Mountain View, CA 94043, USA
| | - Sarah V Badman
- Physics Department, Lancaster University, Lancaster LA1 4YB, UK
| | | | - Bonnie J Buratti
- NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
| | - Kevin H Baines
- NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
| | - Christophe Sotin
- NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
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Pfeifer JC, Bischoff T, Ehlers G, Eckhardt B. Order-disorder transitions in a sheared many-body system. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2015; 92:062208. [PMID: 26764683 DOI: 10.1103/physreve.92.062208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Indexed: 06/05/2023]
Abstract
Motivated by experiments on sheared suspensions that show a transition between ordered and disordered phases, we here study the long-time behavior of a sheared and overdamped two-dimensional system of particles interacting by repulsive forces. As a function of interaction strength and shear rate we find transitions between phases with vanishing and large single-particle diffusion. In the phases with vanishing single-particle diffusion, the system evolves towards regular lattices, usually on very slow time scales. Different lattices can be approached, depending on interaction strength and forcing amplitude. The disordered state appears in parameter regions where the regular lattices are unstable. Correlation functions between the particles reveal the formation of shear bands. In contrast to single-particle densities, the spatially resolved two-particle correlation functions vary with time and allow to determine the phase within a period. As in the case of the suspensions, motion in the state with low diffusivity is essentially reversible, whereas in the state with strong diffusion it is not.
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Affiliation(s)
- Jens C Pfeifer
- Fachbereich Physik, Philipps-Universität Marburg, 35032 Marburg, Germany
| | - Tobias Bischoff
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California, 91125,USA
| | - Georg Ehlers
- Fachbereich Physik, Philipps-Universität Marburg, 35032 Marburg, Germany
| | - Bruno Eckhardt
- Fachbereich Physik, Philipps-Universität Marburg, 35032 Marburg, Germany
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Size distribution of particles in Saturn's rings from aggregation and fragmentation. Proc Natl Acad Sci U S A 2015; 112:9536-41. [PMID: 26183228 DOI: 10.1073/pnas.1503957112] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Saturn's rings consist of a huge number of water ice particles, with a tiny addition of rocky material. They form a flat disk, as the result of an interplay of angular momentum conservation and the steady loss of energy in dissipative interparticle collisions. For particles in the size range from a few centimeters to a few meters, a power-law distribution of radii, ~r(-q) with q ≈ 3, has been inferred; for larger sizes, the distribution has a steep cutoff. It has been suggested that this size distribution may arise from a balance between aggregation and fragmentation of ring particles, yet neither the power-law dependence nor the upper size cutoff have been established on theoretical grounds. Here we propose a model for the particle size distribution that quantitatively explains the observations. In accordance with data, our model predicts the exponent q to be constrained to the interval 2.75 ≤ q ≤ 3.5. Also an exponential cutoff for larger particle sizes establishes naturally with the cutoff radius being set by the relative frequency of aggregating and disruptive collisions. This cutoff is much smaller than the typical scale of microstructures seen in Saturn's rings.
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Cuzzi JN, Burns JA, Charnoz S, Clark RN, Colwell JE, Dones L, Esposito LW, Filacchione G, French RG, Hedman MM, Kempf S, Marouf EA, Murray CD, Nicholson PD, Porco CC, Schmidt J, Showalter MR, Spilker LJ, Spitale JN, Srama R, Sremčević M, Tiscareno MS, Weiss J. An Evolving View of Saturn’s Dynamic Rings. Science 2010; 327:1470-5. [DOI: 10.1126/science.1179118] [Citation(s) in RCA: 99] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- J. N. Cuzzi
- Ames Research Center, NASA, Mail Stop 245-3, Moffett Field, CA 94035–1000, USA
| | - J. A. Burns
- Department of Astronomy, Cornell University, Ithaca, NY 14853, USA
| | - S. Charnoz
- Laboratoire Astrophysique Instrumentation Modélisation, Université Paris Diderot/Commissariat à l’Energie Atomique/CNRS, 91191 Gif sur Yvette Cedex, France
| | - R. N. Clark
- U.S. Geological Survey, Denver, CO 80225, USA
| | - J. E. Colwell
- Department of Physics, University of Central Florida, Orlando, FL 32816, USA
| | - L. Dones
- Department of Space Studies, Southwest Research Institute, Boulder, CO 80302, USA
| | - L. W. Esposito
- Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO 80309–0392, USA
| | - G. Filacchione
- Istituto di Astrofisica Spaziale e Fisica Cosmica, Rome 00133, Italy
| | - R. G. French
- Astronomy Department, Wellesley College, Wellesley, MA 02481, USA
| | - M. M. Hedman
- Department of Astronomy, Cornell University, Ithaca, NY 14853, USA
| | - S. Kempf
- Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, Heidelberg 69117, Germany
| | - E. A. Marouf
- Electrical Engineering Department, San Jose State University, San Jose, CA 95192, USA
| | - C. D. Murray
- Astronomy Unit, Queen Mary University of London, London E1 4NS, UK
| | - P. D. Nicholson
- Department of Astronomy, Cornell University, Ithaca, NY 14853, USA
| | - C. C. Porco
- Cassini Imaging Central Laboratory for Operations (CICLOPS), Space Science Institute, Boulder, CO 80301, USA
| | - J. Schmidt
- Institute for Physics and Astronomy, University of Potsdam, Germany
| | | | - L. J. Spilker
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
| | - J. N. Spitale
- Cassini Imaging Central Laboratory for Operations (CICLOPS), Space Science Institute, Boulder, CO 80301, USA
| | - R. Srama
- Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, Heidelberg 69117, Germany
| | - M. Sremčević
- Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO 80309–0392, USA
| | - M. S. Tiscareno
- Department of Astronomy, Cornell University, Ithaca, NY 14853, USA
| | - J. Weiss
- Cassini Imaging Central Laboratory for Operations (CICLOPS), Space Science Institute, Boulder, CO 80301, USA
- Carleton College, Northfield, MN 55057, USA
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