Ring Particle Composition and Size Distribution

Cuzzi, J. N.; Clark, R. N.; Filacchione, G.; French, R. G.; Johnson, R. E.; Marouf, E. A.; Spilker, L. J.

doi:10.1007/978-1-4020-9217-6_15

Cited by 97 publications

(148 citation statements)

References 165 publications

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“…Ring particles may be treated as aggregates built up of primary grains (9) of a certain size r 1 and mass m 1 . [Observations indicate that particles below a certain radius are absent in dense rings (16).] Denote by m k = km 1 the mass of ring particles of "size" k containing k primary grains and by n k their number density.…”

Section: Resultsmentioning

confidence: 99%

“…If the additional terms [16] and [17] were negligible, compared with the terms [18] that arise for both models, the emergent steady-state size distributions would be the same. For k 1, one can neglect [16] and [17] compared with [18] if α > γ − μ and α > 1.…”

Section: [4]mentioning

confidence: 99%

“…For k 1, one can neglect [16] and [17] compared with [18] if α > γ − μ and α > 1. Taking into account that the equations for the monomers for the two models coincide when α > 2, we arrive at the following criterion for universality of the steady-state distribution: α > maxfγ − μ, 2g.…”

Section: [4]mentioning

confidence: 99%

“…Rather, ring particles are believed to be involved in active accretion-destruction dynamics (5-13) and their sizes vary over a few orders of magnitude as a power law (14)(15)(16)(17), with a sharp cutoff for large sizes (18)(19)(20)(21). Moreover, tidal forces fail to explain the abrupt decay of the size distribution for house-sized particles (22).…”

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confidence: 99%

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Size distribution of particles in Saturn’s rings from aggregation and fragmentation

Brilliantov

Krapivsky

Bodrova

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

135

129

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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. (1-3) and the observation of rapid processes in the ring system (4) indicate that the shape of the particle size distribution is likely not primordial or a direct result of the ring-creating event. Rather, ring particles are believed to be involved in active accretion-destruction dynamics (5-13) and their sizes vary over a few orders of magnitude as a power law (14-17), with a sharp cutoff for large sizes (18-21). Moreover, tidal forces fail to explain the abrupt decay of the size distribution for house-sized particles (22). One wishes to understand the following: (i) Can the interplay between aggregation and fragmentation lead to the observed size distribution? And (ii) is this distribution peculiar for Saturn's rings, or is it universal for planetary rings in general? To answer these questions quantitatively, one needs to elaborate a detailed model of the kinetic processes in which the ring particles are involved. Here we develop a theory that quantitatively explains the observed properties of the particle size distribution and show that these properties are generic for a steady state, when a balance between aggregation and fragmentation holds. Our model is based on the hypothesis that collisions are binary and that they may be classified as aggregative, restitutive, or disruptive (including collisions with erosion); which type of collision is realized depends on the relative speed of colliding particles and their masses. We apply the kinetic theory of granular gases (23, 24) for the multicomponent system of ring particles to quantify the collision rate and the type of collision. Results and DiscussionModel. Ring particles may be treated as aggregates built up of primary grains (9) of a certain size r 1 and mass m 1 . [Observations indicate that particles below a certain radius are absent in dense rings (16).] Denote by m k = km 1 the mass of rin...

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Section: Resultsmentioning

confidence: 99%

Section: [4]mentioning

confidence: 99%

Section: [4]mentioning

confidence: 99%

mentioning

confidence: 99%

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Size distribution of particles in Saturn’s rings from aggregation and fragmentation

Brilliantov

Krapivsky

Bodrova

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

135

129

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“…For neutral-colored surfaces, these small particles may be composed of carbon, while for red-colored surfaces, the particles may be material that is intrinsically red, such as metallic iron or iron oxides. Similarly, the regions of Saturn's rings that exhibit red color may acquire their reflectance and coloration properties from the presence of iron or iron oxides (Cuzzi et al 2009). …”

Section: Introductionmentioning

confidence: 99%

Organic materials in planetary and protoplanetary systems: nature or nurture?

Ore

Fulchignoni

Cruikshank

et al. 2011

A&A

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Aims. The objective of this work is to summarize the discussion of a workshop aimed at investigating the properties, origins, and evolution of the materials that are responsible for the red coloration of the small objects in the outer parts of the solar system. Because of limitations or inconsistencies in the observations and, until recently, the limited availability of laboratory data, there are still many questions on the subject. Our goal is to approach two of the main questions in a systematic way: -Is coloring an original signature of materials that are presolar in origin ("nature") or stems from post-formational chemical alteration, or weathering ("nurture")? -What is the chemical signature of the material that causes spectra to be sloped towards the red in the visible? We examine evidence available both from the laboratory and from observations sampling different parts of the solar system and circumstellar regions (disks). Methods. We present a compilation of brief summaries gathered during the workshop and describe the evidence towards a primordial vs. evolutionary origin for the material that reddens the small objects in the outer parts of our, as well as in other, planetary systems. We proceed by first summarizing laboratory results followed by observational data collected at various distances from the Sun. Results. While laboratory experiments show clear evidence of irradiation effects, particularly from ion bombardment, the first obstacle often resides in the ability to unequivocally identify the organic material in the observations. The lack of extended spectral data of good quality and resolution is at the base of this problem. Furthermore, that both mechanisms, weathering and presolar, act on the icy materials in a spectroscopically indistinguishable way makes our goal of defining the impact of each mechanism challenging. Conclusions. Through a review of some of the workshop presentations and discussions, encompassing laboratory experiments as well as observational data, we infer that both "nature" and "nurture" are instrumental in the coloration of small objects in the outer parts Article published by EDP Sciences A98, page 1 of 14 A&A 533, A98 (2011) of the solar system. While in the case of some observations it is clear that the organic reddening material originated before the solar nebula (i.e. presolar grains found in meteorites), for many other cases pointers are not as clear and indicate a concurrence of both processes.

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Suprathermal magnetospheric minor ions heavier than water at Saturn: Discovery of ²⁸M⁺ seasonal variations

et al. 2014

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Ring Particle Composition and Size Distribution

Cited by 97 publications

References 165 publications

Size distribution of particles in Saturn’s rings from aggregation and fragmentation

Size distribution of particles in Saturn’s rings from aggregation and fragmentation

Organic materials in planetary and protoplanetary systems: nature or nurture?

Suprathermal magnetospheric minor ions heavier than water at Saturn: Discovery of ²⁸M⁺ seasonal variations

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Ring Particle Composition and Size Distribution

Cited by 97 publications

References 165 publications

Size distribution of particles in Saturn’s rings from aggregation and fragmentation

Size distribution of particles in Saturn’s rings from aggregation and fragmentation

Organic materials in planetary and protoplanetary systems: nature or nurture?

Suprathermal magnetospheric minor ions heavier than water at Saturn: Discovery of 28M+ seasonal variations

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Suprathermal magnetospheric minor ions heavier than water at Saturn: Discovery of ²⁸M⁺ seasonal variations