EarthRef.org Reference Database (ERR)
Development and Maintenance by the EarthRef.org Database Team

Detailed Reference Information
Spahn et al. 2003
Spahn, F., Krivov, A.V., Sremcevic, M., Schwarz, U. and Kurths, J. (2003). Stochastic forces in circumplanetary dust dynamics. Journal of Geophysical Research 108. doi: 10.1029/2002JE001925. issn: 0148-0227.

Charged dust grains in circumplanetary environments experience, beyond various deterministic forces, also stochastic perturbations caused, by fluctuations of the magnetic field, the charge of the grains, by chaotic rotation of aspherical grains, etc. Here we investigate the dynamics of a dust population in a circular orbit around a planet which is perturbed by a stochastic planetary magnetic field B', modeled by an isotropically Gaussian white noise. The resulting perturbation equations give rise to a modified diffusion of the inclinations i and eccentricities e: ⟨Δx2⟩ ≈ D Δt (here x = e or i, t is time). The diffusion coefficient is found to be D ∝ ωG2 ∣Δn∣/n2, where the gyrofrequency, the Kepler frequency, and the synodic frequency are denoted by ωG, n, and Δn, respectively. This behavior has been checked against numerical simulations. We have chosen dust grains (1¿m in radius) ejected from Jupiter's satellite Europa in circular equatorial orbits around Jupiter and integrated numerically their trajectories over their typical lifetimes (100 years). The particles were exposed to a Gaussian fluctuating magnetic field B' with the same statistical properties as in the analytical treatment. These simulations have confirmed the analytical results. The theoretical studies showed the statistical properties of B' to be of decisive importance. To estimate them, we analyzed the magnetic field data obtained by the Galileo spacecraft magnetometer at Jupiter and found almost Gaussian fluctuations of about 5% of the mean field and exponentially decaying correlations. This results in a diffusion of orbital inclinations and eccentricities of the dust grains of about ten percent over the lifetime of the particles. For smaller dusty motes or for close-in particles (e.g., in Jovian gossamer rings) stochastics might well dominate the dynamics.

BACKGROUND DATA FILES

Abstract

Keywords
Planetology, Solar System Objects, Dust, Planetology, Solar System Objects, Planetary rings, Magnetospheric Physics, Planetary magnetospheres (5443, 5737, 6030), Mathematical Geophysics, Nonlinear dynamics
Journal
Journal of Geophysical Research
http://www.agu.org/journals/jb/
Publisher
American Geophysical Union
2000 Florida Avenue N.W.
Washington, D.C. 20009-1277
USA
1-202-462-6900
1-202-328-0566
service@agu.org
Click to clear formClick to return to previous pageClick to submit