Mass and Thickness of the Cassini Division in Saturnʼs Rings

Mass and Thickness of the
Cassini Division in Saturnʼs Rings
J. E. Colwell1, L. W. Esposito2, J. H. Cooney1,
R. G. Jerousek1, J. J. Lissauer3, G. R. Stewart2,
M. Sremčević2
1. Dept. of Physics, University of Central Florida
2. LASP, University of Colorado
3. NASA Ames Research Center
Cassini Division
Pandora 9:7
Prometheus 9:7
Pan 6:5
Atlas 5:4
Atlas 6:5
Pan 7:6
Janus 7:5
Wave Analysis Procedure
• Wavelet transforms of data [1, 2].
• Isolate wave through filtering.
1. λ(r) gives σ(r) and average over r.
2. Obtain σ(r) from cumulative phase of wave [3].
3. Add WWZ transforms and get σ(r) from mean
1. Torrence, C. and Compo, G. P. 1998. A Practical Guide to Wavelet Analysis. Bull.
Amer. Met. Soc., 79 61-78.
2. Foster, G. 1996. Wavelets for Period Analysis of Unevenly Sampled Time Series.
Astron. J. 112 1709-1729.
3. Tiscareno, M. S., et al. 2007. Cassini Imaging of Saturn's Rings II. A Wavelet
Technique for Analysis of Density Waves and Other Radial Structure in the Rings.
Icarus 189 14-34.
Cassini Division
Pandora 9:7
Pandora 9:7 Density Wave
Wave on a narrow ringlet
Pandora 9:7
Surface mass density declines with
background optical depth
Cassini Division
Pan 7:6
Pan 7:6
Pan 7:6
Κ=τ/σ is the mass extinction coefficient,
also called the opacity.
If K is similar between waves, use this
to estimate total ring mass.
Mass Extinction Coefficient
Inner edge of A ring
Cassini Division Ramp
Opacity in CD and A Ring
Janus 7:5 wave in CD Ramp