Saturn

Here we draw heavily from the review by L. Spilker (14 June 2019) titled, Cassini-Huygens' exploration of the Saturn system: 13 years of discovery that has appeared in Science, Vol. 364, Issue 6445, pp. 1046 - 1051. This review reminds us to emphasize that, although virtually all of the chapters of our H_Book have been written from the standpoint of analyzing the structure, stability, and dynamics of stars, much of our discussion is applicable in a fairly straightforward manner to studies of planets — especially the gas giants — because they are also self-gravitating fluids.

Structure and Stability

Excerpt from the first paragraph on p. 1050 of L. Spilker (2019):

Saturn's ring system acts like a seismograph, providing a measure of Saturn's internal oscillations (or normal modes) that directly probe the interior of the planet … and provide a means for measuring its deep rotation rate. These vibrations, determined by Saturn's nonuniform internal structure, are probably driven by convection inside the planet, which cause oscillations in Saturn's gravity field … Preliminary modeling of the propagation behavior of this collection of waves provides an interior rotation rate for Saturn of ∼ 10.6 hours …

Hexagon Storm

Image on the Right: obtained from this NASA/JPL site; image on the Left: obtained from this NASA Newsletter. See also the wikipedia page titled, Saturn's hexagon.

FIGURE 1	FIGURE 2

Post Cassini

Binary Mass-Transfer

Several key references:

[Paper DMTF (2006)] M. C. R. D'Souza, P. M. Motl, J. E. Tohline & J. Frank (2006), ApJ, 643, p. 381: Numerical Simulations of the Onset and Stability of dynamical Mass Transfer in Binaries
[Paper MFTD (2007)] P. M. Motl, J. Frank, J. E. Tohline & M. C. R. D'Souza (2007), ApJ, 670, p. 1314: The Stability of Double White Dwarf Binaries Undergoing Direct-Impact Accretion
[Paper MFSCFEDT (2017)] P. M. Motl, J. Frank, J. Staff, G. C. Clayton, C. L. Fryer, W. Even, S. Diehl & J. E. Tohline (2017), ApJSuppl., Vol. 229, Issue 2, article id. 27, 41 pp.: A Comparison of Grid-based and SPH Binary Mass-transfer and Merger Simulations

FIGURE 3: Nonlinear-Amplitude Distortions that Develop in Three Separate Model Evolutions
Evolution A	Evolution B	Evolution C
MFTD (2007) Model Q0.4D Animation: video4.mpg (link is in caption of their Figure 3)	MFSCFEDT (2017) Model Q0.4P_S1 Animation: apjsaa5bdef26_video.mpg (link is in caption of their Figure 26)	MFSCFEDT (2017) ^†Model Q0.5P_G1 Animation: apjsaa5bdef21_video.mpg (link is in caption of their Figure 21)



^†The evolution identified here as Model Q0.5P_G1 was first discussed in §5.2 of DMTF (2006), wherein it was identified as Model Q0.5-Da; the caption to Figure 7 of that paper contains a link to an (mpeg_file = video3-2.mpg) animation that presents a 3D rendering of this model's evolution.

The following discussion has largely been extracted from §3.1.4 of MFSCFEDT (2017):

In §4 of their paper, MFTD (2007) point out that in the vicinity of the accretor some of the models developed nonlinear-amplitude "equatorial distortions with [azimuthal mode numbers] <math>~6 \ge m \ge 3</math>." As is illustrated by the trio of images displayed in the bottom row of Figure 3, above, at a certain point (or points) in each of these binary mass-transfer evolutions … the disk surrounding the accretor has a triangular shape … This trio of triangular shaped images come from, respectively, evolutionary times: (A, B, C) = (15.3, 17.50, 24.33), as measured in terms of initial orbital periods.

Related Discussions

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