Helium in Jupiter's atmosphere: Results from the Galileo probe Helium Interferometer Experiment

Zahn, U. von; Hunten, D. M.; Lehmacher, G. A.

doi:10.1029/98je00695

Cited by 202 publications

(132 citation statements)

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“…Jupiter's atmosphere is clearly depleted in helium, according to Galileo Entry Probe data (von Zahn et al 1998), which is a strong indication that helium phase separation has occurred in this planet. Furthermore the atmosphere's depletion in neon (Mahaffy et al 2000) is strongly suggestive of helium demixing as well, as neon is expected to preferentially dissolve into helium-rich droplets (Roulston & Stevenson 1995;Wilson & Militzer 2010).…”

Section: Jupiter and Saturnmentioning

confidence: 99%

Self-Consistent Model Atmospheres and the Cooling of the Solar System's Giant Planets

Fortney¹,

Ikoma²,

Nettelmann³

et al. 2011

ApJ

139

149

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We compute grids of radiative-convective model atmospheres for Jupiter, Saturn, Uranus, and Neptune over a range of intrinsic fluxes and surface gravities. The atmosphere grids serve as an upper boundary condition for models of the thermal evolution of the planets. Unlike previous work, we customize these grids for the specific properties of each planet, including the appropriate chemical abundances and incident fluxes as a function of solar system age. Using these grids, we compute new models of the thermal evolution of the major planets in an attempt to match their measured luminosities at their known ages. Compared to previous work, we find longer cooling times, predominantly due to higher atmospheric opacity at young ages. For all planets, we employ simple "standard" cooling models that feature adiabatic temperature gradients in the interior H/He and water layers, and an initially hot starting point for the calculation of subsequent cooling. For Jupiter, we find a model cooling age ∼10% longer than previous work, a modest quantitative difference. This may indicate that the hydrogen equation of state used here overestimates the temperatures in the deep interior of the planet. For Saturn, we find a model cooling age ∼20% longer than previous work. However, an additional energy source, such as that due to helium phase separation, is still clearly needed. For Neptune, unlike in work from the 1980s and 1990s, we match the measured T eff of the planet with a model that also matches the planet's current gravity field constraints. This is predominantly due to advances in the high-pressure equation of state of water. This may indicate that the planet possesses no barriers to efficient convection in its deep interior. However, for Uranus, our models exacerbate the well-known problem that Uranus is far cooler than calculations predict, which could imply strong barriers to interior convective cooling. The atmosphere grids are published here as tables, so that they may be used by the wider community.

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Section: Jupiter and Saturnmentioning

confidence: 99%

Self-Consistent Model Atmospheres and the Cooling of the Solar System's Giant Planets

Fortney¹,

Ikoma²,

Nettelmann³

et al. 2011

ApJ

139

149

View full text Add to dashboard Cite

show abstract

“…The helium abundance in the external envelope is taken as Y = 0.238 ± 0.007 to match the in situ observations made by the Galileo probe (Zahn et al 1998). To explain helium depletion compared to the protosolar value (0.270 ± 0.005, Bahcall & Pinsonneault 1995), we assume that a helium phase transition occurs at a pressure P sep , between 0.8 and 4 Mbar according to the immiscibility calculations of Morales et al (2013).…”

Section: Modeling Jupitermentioning

confidence: 99%

Jupiter internal structure: the effect of different equations of state

Miguel

Guillot

Fayon

2016

A&A

103

161

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Context. Heavy elements, even though they are a smaller constituent, are crucial to understand the formation history of Jupiter. Interior models are used to determine the amount of heavy elements in the interior of Jupiter, but this range is still subject to degeneracies because of the uncertainties in the equations of state. Aims. Before Juno mission data arrive, we present optimized calculations for Jupiter that explore the effect of different model parameters on the determination of the core and the mass of heavy elements of Jupiter. We compare recently published equations of state.Methods. The interior model of Jupiter was calculated from the equations of hydrostatic equilibrium, mass, and energy conservation, and energy transport. The mass of the core and heavy elements was adjusted to match the observed radius and gravitational moments of Jupiter. Results. We show that the determination of the interior structure of Jupiter is tied to the estimation of its gravitational moments and the accuracy of equations of state of hydrogen, helium, and heavy elements. Locating the region where helium rain occurs and defining its timescale is important to determine the distribution of heavy elements and helium in the interior of Jupiter. We show that the differences found when modeling the interior of Jupiter with recent EOS are more likely due to differences in the internal energy and entropy calculation. The consequent changes in the thermal profile lead to different estimates of the mass of the core and heavy elements, which explains differences in recently published interior models of Jupiter. Conclusions. Our results help clarify the reasons for the differences found in interior models of Jupiter and will help interpreting upcoming Juno data.

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“…For the duration of the initial homogeneous phase, the differences in T eff and R between tracks stem solely from the heavy element core mass M c , since that parameter adjusts the mean Hanel et al (1981) c von Zahn et al (1998) c Seidelmann et al (2007) density and hence the total radius of the planet. As described in §3.1, the time at which phase separation sets in (and Y atm first diverges from the protosolar value) is set by ∆T phase , and the trend toward later phase separation onset with increasing R ρ is the result of the two parameters' substantial covariance.…”

Section: Bayesian Parameter Estimationmentioning

confidence: 99%

Bayesian Evolution Models for Jupiter With Helium Rain and Double-Diffusive Convection

Mankovich

Fortney

Moore

2016

ApJ

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Hydrogen and helium demix when sufficiently cool, and this bears on the evolution of all giant planets at large separations at or below roughly a Jupiter mass. We model the thermal evolution of Jupiter, including its evolving helium distribution following results of ab initio simulations for helium immiscibility in metallic hydrogen. After 4 Gyr of homogeneous evolution, differentiation establishes a thin helium gradient below 1 Mbar that dynamically stabilizes the fluid to convection. The region undergoes overstable double-diffusive convection (ODDC), whose weak heat transport maintains a superadiabatic temperature gradient. With a generic parameterization for the ODDC efficiency, the models can reconcile Jupiter's intrinsix flux, atmospheric helium content, and radius at the age of the solar system if the Lorenzen et al. H-He phase diagram is translated to lower temperatures. We cast the evolutionary models in an MCMC framework to explore tens of thousands of evolutionary sequences, retrieving probability distributions for the total heavy element mass, the superadiabaticity of the temperature gradient due to ODDC, and the phase diagram perturbation. The adopted SCvH-I equation of state favors inefficient ODDC such that a thermal boundary layer is formed, allowing the molecular envelope to cool rapidly while the deeper interior actually heats up over time. If the overall cooling time is modulated with an additional free parameter to imitate the effect of a colder or warmer EOS, the models favor those that are colder than SCvH-I. In this case the superadiabaticity is modest and a warming or cooling deep interior are equally likely. Subject headings: planets and satellites: physical evolution -planets and satellites: interiors -planets and satellites: individual (Jupiter) -methods: statistical 1. INTRODUCTION Cool giant planets are relics of the protoplanetary systems from which they formed in the sense that they do not fuse protons, and they are well-bound enough that even hydrogen does not escape appreciably over tens of billions of years. Their thermal evolution is thus relatively simple, and understanding it empowers us to use the present states of giant planets to learn about their history and formation. The open questions about planet formation thus motivate a comprehensive theory of giant planet evolution, which will continue to be driven heavily by our own, well-studied giant planets, Jupiter and Saturn.A Henyey-type stellar evolution calculation for a Jupitermass object was first performed by Graboske et al. (1975), who showed that a convective, homogeneous sphere of fluid hydrogen and helium could cool to Jupiter's observed luminosity over roughly the right timescale, and noted that among all model inputs, the equation of state (EOS) and superadiabaticity of the temperature gradient have the strongest influence on the overall cooling time.These two fundamental physical inputs are closely related. The EOS (paired with a hydrostatic model) is necessary to translate the planet's tangible properties...

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Helium in Jupiter's atmosphere: Results from the Galileo probe Helium Interferometer Experiment

Cited by 202 publications

References 33 publications

Self-Consistent Model Atmospheres and the Cooling of the Solar System's Giant Planets

Self-Consistent Model Atmospheres and the Cooling of the Solar System's Giant Planets

Jupiter internal structure: the effect of different equations of state

Bayesian Evolution Models for Jupiter With Helium Rain and Double-Diffusive Convection

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