TY  - JOUR
A1  - Brilliantov, Nikolai V.
A1  - Krapivsky, P. L.
A1  - Bodrova, Anna
A1  - Spahn, Frank
A1  - Hayakawa, Hisao
A1  - Stadnichuk, Vladimir
A1  - Schmidt, Jurgen
T1  - Size distribution of particles in Saturn's rings from aggregation and fragmentation
JF  - Proceedings of the National Academy of Sciences of the United States of America
N2  - 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, similar to r(-q) with q approximate to 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.
KW  - planetary rings
KW  - kinetic theory
KW  - coagulation-fragmentation
Y1  - 2015
U6  - https://doi.org/10.1073/pnas.1503957112
SN  - 0027-8424
VL  - 112
IS  - 31
SP  - 9536
EP  - 9541
PB  - National Acad. of Sciences
CY  - Washington
ER  -