Saturn Helium Abundance: A Reanalysis of Voyager Measurements

Conrath, B. J.; Gautier, D.

doi:10.1006/icar.1999.6265

Cited by 209 publications

(176 citation statements)

References 22 publications

(27 reference statements)

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“…One of the possibile explanations for this anomalous luminosity is the energy released by gravitational differentiation of helium from hydrogen, with He gradually sinking towards the interior [168]. This is consistent with analyses of Voyager data that suggest a depletion of He from the Saturn's surface, with an atmospheric value of about 4-7.5% molar fraction (15-25% mass fraction, to be compared with an overall planetary value of 28%, as determined from the abundance of the primordial solar system) [13,169]. The density profile of giant planets is poorly constrained (but the spacecraft Cassini is expected to refine the values of Saturn's gravitational moments J 4 and J 6 , and thus to add better contraints on its density profile during this year's flyby).…”

Section: Giant Planets 31 Jupiter and Saturnsupporting

confidence: 85%

Ab initio theory of planetary materials

Oganov

Price²,

Scandolo³

2005

Zeitschrift Für Kristallographie - Crystalline Materials

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Abstract. Ab initio simulations play an increasingly important role in the studies of deep planetary interiors. Here we review the current state of this field, concentrating on studies of the materials of the Earth's deep interior (MgO--SiO 2 --FeO--Al 2 O 3 , Fe--Si--S--O) and of the interiors of giant planets (H--He system, H 2 O--CH 4 --NH 3 system). In particular, novel phases and phase diagrams, insights into structural and electronic phase transitions, melting curves, thermoelasticity and the effects of impurities on physical properties of planet-forming materials are discussed.

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Section: Giant Planets 31 Jupiter and Saturnsupporting

confidence: 85%

Ab initio theory of planetary materials

Oganov

Price²,

Scandolo³

2005

Zeitschrift Für Kristallographie - Crystalline Materials

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“…As Figure 5 shows, this phase diagram prolongs Saturn's cooling only 0.8 Gyr, even in the most favorable circumstance that all energy liberated is available to be radiated, and does not instead go into heating the planet's deep interior. Fortney & Hubbard (2003) next inverted the problem to derive an ad-hoc phase diagram that could simultaneously explain Saturn's current luminosity as well as its current atmospheric helium abundance (Conrath & Gautier 2000). The helium abundance is depleted relative to the Sun, and is consistent with helium being lost to deeper regions of liquid metallic hydrogen at Mbar pressures.…”

Section: Results: Evolution Of Jupiter and Saturnmentioning

confidence: 99%

The Interior Structure, Composition, and Evolution of Giant Planets

2009

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We discuss our current understanding of the interior structure and thermal evolution of giant planets. This includes the gas giants, such as Jupiter and Saturn, that are primarily composed of hydrogen and helium, as well as the "ice giants," such as Uranus and Neptune, which are primarily composed of elements heavier than H/He. The effect of different hydrogen equations of state (including new first-principles computations) on Jupiter's core mass and heavy element distribution is detailed. This variety of the hydrogen equations of state translate into an uncertainty in Jupiter's core mass of 18M ⊕ . For Uranus and Neptune we find deep envelope metallicities up to 0.95, perhaps indicating the existence of an eroded core, as also supported by their low luminosity. We discuss the results of simple cooling models of our solar system's planets, and show that more complex thermal evolution models may be necessary to understand their cooling history. We review how measurements of the masses and radii of the nearly 50 transiting extrasolar giant planets are changing our understanding of giant planets. In particular a fraction of these planets appear to be larger than can be accommodated by standard models of planetary contraction. We review the proposed explanations for the radii of these planets. We also discuss very young giant planets, which are being directly imaged with ground-and space-based telescopes.Keywords giant planet interiors · exoplanets ⋆ Both authors contributed equally to this work.

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“…These planets, generally believed to have been formed approximately at the same time as the sun, are essentially made of hydrogen and helium, with a helium mass fraction at the surface of Y = 0.234 ±0.005 for Jupiter (von Zahn et al, 1998) and Y = 0.18-0.25 for Saturn (Conrath and Gautier, 2000). The estimated protosolar helium mass fraction is Y ∼ 0.27 (Bahcall et al, 1995).…”

Section: Helium and Hydrogen-helium Mixturesmentioning

confidence: 99%

The properties of hydrogen and helium under extreme conditions

McMahon¹,

Morales²,

Pierleoni³

et al. 2012

Rev. Mod. Phys.

478

415

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Hydrogen and helium are the most abundant elements in the universe and, in principle, are the simplest elements. Nonetheless, they display remarkable properties under pressure that have fascinated theoreticians and experimentalists for over a century. Recent advances in computational methods have made it possible to elucidate many of these properties. We review some of the computational methods that have been applied to dense hydrogen and helium in recent years, mainly those that perform a simulation directly from the physical picture of electrons and ions; primarily, those based on density functional theory and quantum Monte Carlo methods. We then discuss the predictions from such methods as applied to the phase diagram of hydrogen, including the solid and fluid phases, with particular focus on the crystal structures, the liquidliquid transition and comparison of the results with experimental shock-wave data. We then discuss predictions of ordered quantum states, including a possible low-temperature fluid and high-temperature superconductivity in the atomic state. We also briefly discuss pure helium, and then focus on hydrogen-helium mixtures, with particular focus on properties of relevance to planetary science.

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Saturn Helium Abundance: A Reanalysis of Voyager Measurements

Cited by 209 publications

References 22 publications

Ab initio theory of planetary materials

Ab initio theory of planetary materials

The Interior Structure, Composition, and Evolution of Giant Planets

The properties of hydrogen and helium under extreme conditions

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