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 - TY - JOUR A1 - Meier, Patrick A1 - Motschmann, Uwe A1 - Schmidt, Jurgen A1 - Spahn, Frank A1 - Hill, Thomas W. A1 - Dong, Yaxue A1 - Jones, Geraint H. A1 - Kriegel, Hendrik T1 - Modeling the total dust production of Enceladus from stochastic charge equilibrium and simulations JF - Planetary and space science KW - Enceladus KW - Plume KW - Nanograin charge KW - CAPS Y1 - 2015 U6 - https://doi.org/10.1016/j.pss.2015.10.002 SN - 0032-0633 VL - 119 SP - 208 EP - 221 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Liu, Xiaodong A1 - Sachse, Manuel A1 - Spahn, Frank A1 - Schmidt, Jurgen T1 - Dynamics and distribution of Jovian dust ejected from the Galilean satellites JF - Journal of geophysical research, Planets N2 - In this paper, the dynamical analysis of the Jovian dust originating from the four Galilean moons is presented. High-accuracy orbital integrations of dust particles are used to determine their dynamical evolution. A variety of forces are taken into account, including the Lorentz force, solar radiation pressure, Poynting-Robertson drag, solar gravity, the satellites' gravity, plasma drag, and gravitational effects due to nonsphericity of Jupiter. More than 20,000 dust particles from each source moon in the size range from 0.05 μm to 1 cm are simulated over 8000 (Earth) years until each dust grain hits a sink (moons, Jupiter, or escape from the system). Configurations of dust number density in the Jovicentric equatorial inertial frame are calculated and shown. In a Jovicentric frame rotating with the Sun the dust distributions are found to be asymmetric. For certain small particle sizes, the dust population is displaced towards the Sun, while for certain larger sizes, the dust population is displaced away from the Sun. The average lifetime as a function of particle size for ejecta from each source moon is derived, and two sharp jumps in the average lifetime are analyzed. Transport of dust between the Galilean moons and to Jupiter is investigated. Most of the orbits for dust particles from Galilean moons are prograde, while, surprisingly, a small fraction of orbits are found to become retrograde mainly due to solar radiation pressure and Lorentz force. The distribution of orbital elements is also analyzed. Y1 - 2016 U6 - https://doi.org/10.1002/2016JE004999 SN - 2169-9097 SN - 2169-9100 VL - 121 SP - 1141 EP - 1173 PB - American Geophysical Union CY - Washington ER -