Enceladus' south polar sea

Collins, G. C.; Goodman, J. C.

doi:10.1016/j.icarus.2007.01.010

Cited by 113 publications

(116 citation statements)

References 16 publications

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“…This could be evidence in support of the liquid water sea model of Collins and Goodman [2007]. The larger, shallower shape of the SPD probably relates to the fact that it is tectonically active.…”

Section: South Polar Depressionsupporting

confidence: 58%

One‐hundred‐km‐scale basins on Enceladus: Evidence for an active ice shell

Schenk

McKinnon²

2009

Geophysical Research Letters

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Stereo‐derived topographic mapping of ∼50% of Enceladus reveals at least 6 large‐scale, ovoid depressions (basins) 90–175 km across and 800‐to‐1500 m deep and uncorrelated with geologic boundaries. In contrast, the south polar depression is larger and apparently shallower and correlates with active resurfacing. The shape and scale of the basins is inconsistent with impact, geoid surface deflections, or with dynamically supported topography. Isostatic thinning of Enceladus' ice shell associated with upwellings (and tidally‐driven ice melting) can plausibly account for these basins. Thinning implies upwarping of the base of the shell of ∼10–20 km beneath the depressions, depending on total shell thickness; loss of near‐surface porosity due to enhanced heat flow may also contribute to basin lows. Alternatively, the basins may overly cold, inactive, and hence denser ice, but thermal isostasy alone requires thermal expansion more consistent with clathrate hydrate than water ice.

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Section: South Polar Depressionsupporting

confidence: 58%

One‐hundred‐km‐scale basins on Enceladus: Evidence for an active ice shell

Schenk

McKinnon²

2009

Geophysical Research Letters

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“…One end-member compensation model is to assume that compensation occurs at the base of an ice shell floating on a global ocean (27). In this case, adopting the parameters given in Table S6, we estimate the compensation depth (i.e., ice shell thickness) required to match the calculated admittance to be roughly 20-40 km (see Figure S6 and eq.…”

Section: S35 Isostatic Compensationmentioning

confidence: 99%

The Gravity Field and Interior Structure of Enceladus

Iess

Stevenson

Parisi

et al. 2014

Science

389

415

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The small and active Saturnian moon Enceladus is one of the primary targets of the Cassini mission. We determined the quadrupole gravity field of Enceladus and its hemispherical asymmetry using Doppler data from three spacecraft flybys. Our results indicate the presence of a negative mass anomaly in the south-polar region, largely compensated by a positive subsurface anomaly compatible with the presence of a regional subsurface sea at depths of 30 to 40 kilometers and extending up to south latitudes of about 50 degrees. The estimated values for the largest quadrupole harmonic coefficients (10(6)J(2) = 5435.2 +/- 34.9, 10(6)C(22) = 1549.8 +/- 15.6, 1 sigma) and their ratio (J(2)/C-22 = 3.51 +/- 0.05) indicate that the body deviates mildly from hydrostatic equilibrium. The moment of inertia is around 0.335MR(2), where M is the mass and R is the radius, suggesting a differentiated body with a low-density core

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“…In the Solar System such subsurface oceans exist in Europa, Titan, Enceladus, and possibly also in Ganymede and Callisto. The liquid phase state of these oceans are maintained by tidal heat production, freezing point depressing solved ingredients, and/or internal heat due to accretional energy conservation and radiogenic heat (Carr et al 1998;Khurana et al 1998;Kargel et al 2000;Zimmer et al 2000;McCord et al 2001;Schenk 2002;Collins & Goodman 2007;Roberts & Nimmo 2008;Lorenz et al 2008;Postberg et al 2009;Iess et al 2014;Dobos & Turner 2015). Having information on the existence of surface ice, using mass estimation from TTV and TDV might increase the probability to identify exomoons that are probable of having subsurface oceans.…”

Section: Importance Of Icementioning

confidence: 99%

Possibility for albedo estimation of exomoons: Why should we care about M dwarfs?

Dobos¹,

Keresztúri²,

Pál³

et al. 2016

A&A

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Occultation light curves of exomoons may give information on their albedo and hence indicate the presence of ice cover on the surface. Icy moons might have subsurface oceans thus these may potentially be habitable. The objective of our paper is to determine whether next generation telescopes will be capable of albedo estimations for icy exomoons using their occultation light curves. The success of the measurements depends on the depth of the moon's occultation in the light curve and on the sensitivity of the used instruments. We applied simple calculations for different stellar masses in the V and J photometric bands, and compared the flux drop caused by the moon's occultation and the estimated photon noise of next generation missions with 5 σ confidence. We found that albedo estimation by this method is not feasible for moons of solar-like stars, but small M dwarfs are better candidates for such measurements. Our calculations in the J photometric band show that E-ELT MICADO's photon noise is just about 4 ppm greater than the flux difference caused by a 2 Earth-radii icy satellite in a circular orbit at the snowline of an 0.1 stellar mass star. However, considering only photon noise underestimates the real expected noise, because other noise sources, such as CCD read-out and dark signal become significant in the near infrared measurements. Hence we conclude that occultation measurements with next generation missions are far too challenging, even in the case of large, icy moons at the snowline of small M dwarfs. We also discuss the role of the parameters that were neglected in the calculations, e.g. inclination, eccentricity, orbiting direction of the moon. We predict that the first albedo estimations of exomoons will probably be made for large icy moons around the snowline of M4 -M9 type main sequence stars.

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Enceladus' south polar sea

Cited by 113 publications

References 16 publications

One‐hundred‐km‐scale basins on Enceladus: Evidence for an active ice shell

One‐hundred‐km‐scale basins on Enceladus: Evidence for an active ice shell

The Gravity Field and Interior Structure of Enceladus

Possibility for albedo estimation of exomoons: Why should we care about M dwarfs?

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