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Phase diagram for hydrogen with the main phase transitions occurring in the fluid or gas phase. The temperature-pressure profiles for Jupiter, Saturn, Uranus, Neptune, and the exoplanet HD 209458 b are shown. The dashed nearly vertical line near 1 Mbar is indicative of the molecular to metallic transition (here it represents the so-called plasma phase transition as calculated by Saumon et al. (1995)). The region in which hydrogen is in solid phase (Datchi et al., 2000; Gregoryanz et al., 2003) is represented as a hatched area. The three phases (I,II,III) of solid hydrogen are shown (see Mao and Hemley, 1994). Values of the degeneracy parameter θ are indicated as dotted lines to the upper right corner of the figure.

Phase diagram for hydrogen with the main phase transitions occurring in the fluid or gas phase. The temperature-pressure profiles for Jupiter, Saturn, Uranus, Neptune, and the exoplanet HD 209458 b are shown. The dashed nearly vertical line near 1 Mbar is indicative of the molecular to metallic transition (here it represents the so-called plasma phase transition as calculated by Saumon et al. (1995)). The region in which hydrogen is in solid phase (Datchi et al., 2000; Gregoryanz et al., 2003) is represented as a hatched area. The three phases (I,II,III) of solid hydrogen are shown (see Mao and Hemley, 1994). Values of the degeneracy parameter θ are indicated as dotted lines to the upper right corner of the figure.

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Article
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We review the interior structure and evolution of Jupiter, Saturn, Uranus and Neptune, and giant exoplanets with particular emphasis on constraining their global composition. Compared to the first edition of this review, we provide a new discussion of the atmospheric compositions of the solar system giant planets, we discuss the discovery of oscill...

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Context 1
... coupled (coulomb inter- actions between ions are not dominant but must be taken into account). The presence of many elements and their possible interactions further complicate matters. For lack of space, this section will mostly focus on hydrogen whose EOS has seen the most important developments in recent years. A phase diagram of hydrogen ( fig. 5) illustrates some of the important phenomena that occur in giant ...
Context 2
... implies that electrons are degenerate. Figure 5 shows that inside Jupiter, Saturn, the extrasolar planet HD 209458 b, but also for giant planets in general for most of their history, the degeneracy parameter θ = T /T F is between 0.1 and 0.03. Therefore, the energy of electrons in the interior is expected to be only slightly larger than their non-relativistic, fully degenerate limit: u e ≥ 3/5 kT F = 15.6 (ρ/µ e ) 2/3 eV, where k is Boltzmann's constant, µ e is the number of electrons per nucleon and ρ is the density in g cm −3 . ...
Context 3
... et al. (1995)). The region in which hydrogen is in solid phase ( Datchi et al., 2000;Gregoryanz et al., 2003) is represented as a hatched area. The three phases (I,II,III) of solid hydrogen are shown (see Mao and Hemley, 1994). Values of the degeneracy parameter θ are indicated as dotted lines to the upper right corner of the figure. suggested in Fig. 5 -or first metallizes in the molecular state H 2 remains to be ...
Context 4
... question of the existence of a first-order molecular to metallic transition of hydrogen (i.e. both molecular dissociation and ionisation occur simultaneously and discontinuously at the so-called plasma phase transition, or PPT) remains however. The critical line shown in fig. 5 corresponds to calculations by Saumon et al. (1995), but may be caused by artefacts in the free energy calculation. Recent Density Functional Theory (DFT) simulations by Bonev et al. (2004) indicate the possibility of a first order liquid-liquid transition but other path-integral calculations ( Militzer et al., 2001) do not. It is ...
Context 5
... clear result from fig. 5 at least is that, as first shown by Hubbard (1968), the interiors of the hydrogen-helium giant planets are fluid, whatever their age: of course, they avoid the critical point for the liquid gas transition in hydrogen and helium, at very low temperatures, but they also lie comfortably above the solidification lines for hydrogen and ...

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