http://arxiv.org/abs/1805.10286
Seismology of the gas giants holds the potential to resolve long-standing questions about their internal structure and rotation state. We construct a family of Saturn interior models constrained by the gravity field and compute their adiabatic mode eigenfrequencies and corresponding Lindblad and vertical resonances in Saturn’s C ring, where more than twenty waves with pattern speeds faster than the ring mean motion have been detected and characterized using high-resolution Cassini Visual and Infrared Mapping Spectrometer stellar occultation data. We present identifications of the fundamental acoustic modes of Saturn that appear to be the origin of these observed ring waves, and use their observed pattern speeds and azimuthal wavenumbers to estimate the bulk rotation period of Saturn’s interior to be $10\ {\rm hours}\ 35.3^{+2.3}_{-1.7}\ {\rm minutes}$ (median and 5%/95% quantiles), significantly faster than the period measured from Voyager spacecraft radiometry. Structure in the resulting pattern speed residuals suggests the presence of differential rotation in Saturn’s outer envelope.
C. Mankovich, M. Marley, J. Fortney, et. al.
Tue, 29 May 18
31/73
Comments: 17 pages, 6 figures, submitted to ApJ
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