Cassini Ring Seismology as a Probe of Saturn's Interior. I. Rigid Rotation

Christopher Mankovich, Mark S. Marley, Jonathan J. Fortney, Naor Movshovitz

Research output: Contribution to journalArticlepeer-review

38 Scopus citations

Abstract

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 20 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 modes of Saturn that appear to be the origin of these observed ring waves, and we use their observed pattern speeds and azimuthal wavenumbers to estimate the bulk rotation period of Saturn's interior to be (median and 5%/95% quantiles), significantly faster than Voyager and Cassini measurements of periods in Saturn's kilometric radiation, the traditional proxy for Saturn's bulk rotation period. The global fit does not exhibit any clear systematics indicating strong differential rotation in Saturn's outer envelope.

Original languageEnglish (US)
Article number1
JournalAstrophysical Journal
Volume871
Issue number1
DOIs
StatePublished - Jan 20 2019
Externally publishedYes

Keywords

  • planets and satellites: individual (Saturn)
  • planets and satellites: interiors
  • planets and satellites: rings

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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