Kronoseismology V: A panoply of waves in Saturn’s C ring driven by high-order internal planetary oscillations

French, R. G.; Bridges, Bill; Hedman, Matthew M.; Nicholson, P. D.; Mankovich, Christopher; McGhee-French, Colleen A.

doi:10.1016/j.icarus.2021.114660

Cited by 6 publications

(20 citation statements)

References 24 publications

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“…Finally, we can consider the m = 3 wave signatures found outside the plateaux. Note that unlike the more complex signatures found inside the various plateaux, these features are more consistent with individual waves, and will therefore be designated as such based on their radial locations within the rings, consistent with prior work (Hedman & Nicholson 2013, 2014French et al 2016French et al , 2019Hedman et al 2019;French et al 2021).…”

Section: = 3 Wave Signals Outside Of Plateauxsupporting

confidence: 65%

“…Saturn's rings contain multiple structures that are generated by resonances with asymmetries and oscillations within the planet (Hedman & Nicholson 2013, 2014French et al 2016French et al , 2019Hedman et al 2019;French et al 2021). Many of these waves are likely generated by planetary normal mode oscillations, and precise measurements of these oscillation frequencies have already yielded new insights into Saturn's internal structure and rotation rate (Fuller 2014;Mankovich et al 2019;.…”

Section: Introductionmentioning

confidence: 99%

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Kronoseismology. VI. Reading the Recent History of Saturn’s Gravity Field in Its Rings

et al. 2022

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Saturn’s C ring contains multiple structures that appear to be density waves driven by time-variable anomalies in the planet’s gravitational field. Semiempirical extensions of density wave theory enable the observed wave properties to be translated into information about how the pattern speeds and amplitudes of these gravitational anomalies have changed over time. Combining these theoretical tools with wavelet-based analyses of data obtained by the Visual and Infrared Mapping Spectrometer on board the Cassini spacecraft reveals a suite of structures in Saturn’s gravity field with azimuthal wavenumber 3, rotation rates between 804° day−1 and 842° day−1, and local gravitational potential amplitudes between 30 and 150 cm2 s−2. Some of these anomalies are transient, appearing and disappearing over the course of a few Earth years, while others persist for decades. Most of these persistent patterns appear to have roughly constant pattern speeds, but there is at least one structure in the planet’s gravitational field whose rotation rate steadily increased between 1970 and 2010. This gravitational field structure appears to induce two different asymmetries in the planet’s gravity field, one with azimuthal wavenumber 3 that rotates at roughly 810° day−1 and another with azimuthal wavenumber 1 rotating three times faster. The atmospheric processes responsible for generating the latter pattern may involve solar tides.

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Section: = 3 Wave Signals Outside Of Plateauxsupporting

confidence: 65%

Section: Introductionmentioning

confidence: 99%

Kronoseismology. VI. Reading the Recent History of Saturn’s Gravity Field in Its Rings

et al. 2022

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“…While the interiors of Uranus and Neptune remain largely hidden, their ring systems are available for eas-ier observation. Recent analyses of Saturn's rings have demonstrated that certain ring features are likely generated by resonances with normal modes inside the planet (Hedman & Nicholson 2013, 2014French et al 2016Hedman et al 2019;French et al 2021;Hedman et al 2022), confirming predictions made by Marley & Porco (1993) and providing new insights into that planet's interior. Furthermore, Marley et al (1988) performed preliminary calculations and found that resonances with a few Uranian normal modes could potentially fall close to some of the Uranian rings (see Table 6 in the Appendices).…”

Section: Introductionmentioning

confidence: 56%

“…Meanwhile, Marley (1991) and Marley & Porco (1993), building upon ideas from Stevenson (1982), showed that certain normal modes in Saturn's interior could cause gravitational perturbations in the C ring, and proposed potential correlations between some of the waves and specific planetary f-modes. Once the Cassini mission arrived at Saturn, new waves were detected (Baillié et al 2011) and several features were confirmed to be generated by resonances with planetary oscillations and asymmetries (Hedman & Nichol-son 2013, 2014French et al 2016Hedman et al 2019;French et al 2021;Hedman et al 2022). These studies yielded the azimuthal wavenumber and the precise frequency for a set of planetary normal modes that provide evidence for a stably stratified layer within the planet (Fuller 2014), an estimate for Saturn's bulk rotation rate (Mankovich et al 2019), evidence for a diffuse core , and constraints on differential rotation (Dewberry et al 2021).…”

Section: Overview Of Ring Seismologymentioning

confidence: 99%

Ring Seismology of the Ice Giants Uranus and Neptune

A'Hearn¹,

Hedman²,

Mankovich³

et al. 2022

Preprint

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We assess the prospect of using ring seismology to probe the interiors of the ice giants Uranus and Neptune. We do this by calculating normal mode spectra for different interior models of Uranus and Neptune using the stellar oscillation code GYRE. These spectra provide predictions of where in these planets' ring systems the effects of interior oscillations might be detected. We find that f-mode resonances with azimuthal order m = 2 or 7 ≤ m ≤ 19 fall among the inner rings (6, 5, 4, α, and β) of Uranus, while f-mode resonances with 2 ≤ m ≤ 12 fall in the tenuous ζ ring region. In addition, f-mode resonances with m = 2 or 6 ≤ m ≤ 13 may give azimuthal structure to Neptune's tenuous Galle ring. We also find that g-mode resonances may fall in the middle to outer rings of these planets. Although an orbiter is most likely required to confirm the association between any waves in the rings and planetary normal modes, the diversity of normal mode spectra implies that identification of just one or two modes in the rings of Uranus or Neptune would eliminate a variety of interior models, and thus aid in the interpretation of Voyager observations and future spacecraft measurements.

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“…While the interiors of Uranus and Neptune remain largely hidden, their ring systems are available for easier observation. Recent analyses of Saturn's rings have demonstrated that certain ring features are likely generated by resonances with normal modes inside the planet (Hedman & Nicholson 2013French et al 2016Hedman et al 2019;French et al 2021;Hedman et al 2022), confirming predictions made by Marley & Porco (1993) and providing new insights into that planet's interior. Furthermore, Marley et al (1988) performed preliminary calculations and found that resonances with a few Uranian normal modes could potentially fall close to some of the Uranian rings (see Table 6 in Appendix A).…”

Section: Introductionmentioning

confidence: 60%

Ring Seismology of the Ice Giants Uranus and Neptune

A'Hearn¹,

Hedman²,

Mankovich³

et al. 2022

Planet. Sci. J.

Self Cite

View full text Add to dashboard Cite

We assess the prospect of using ring seismology to probe the interiors of the ice giants Uranus and Neptune. We do this by calculating normal-mode spectra for different interior models of Uranus and Neptune using the stellar oscillation code GYRE. These spectra provide predictions of where in these planets’ ring systems the effects of interior oscillations might be detected. We find that f-mode resonances with azimuthal order m = 2 or 7 ≤ m ≤ 19 fall among the inner rings (6, 5, 4, α, and β) of Uranus, while f-mode resonances with 2 ≤ m ≤ 12 fall in the tenuous ζ ring region. In addition, f-mode resonances with m = 2 or 6 ≤ m ≤ 13 may give azimuthal structure to Neptune’s tenuous Galle ring. We also find that g-mode resonances may fall in the middle to outer rings of these planets. Although an orbiter is most likely required to confirm the association between any waves in the rings and planetary normal modes, the diversity of normal-mode spectra implies that identification of just one or two modes in the rings of Uranus or Neptune would eliminate a variety of interior models and thus aid in the interpretation of Voyager observations and future spacecraft measurements.

show abstract

Kronoseismology V: A panoply of waves in Saturn’s C ring driven by high-order internal planetary oscillations

Cited by 6 publications

References 24 publications

Kronoseismology. VI. Reading the Recent History of Saturn’s Gravity Field in Its Rings

Kronoseismology. VI. Reading the Recent History of Saturn’s Gravity Field in Its Rings

Ring Seismology of the Ice Giants Uranus and Neptune

Ring Seismology of the Ice Giants Uranus and Neptune

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