Neptune formation

Reactions in Molten Salt Solutions. I. Uranate and Neptunate Formation in Molten Lithium Nitrate-Sodium Nitrate, W.T. Camall, S.J. Neufeldt, and A. Walker, Inorg. Chem. 4, 1808-1813 (1965). 

Effects of condensation are also seen in the bulk compositions of the planets and their satellites. The outer planets, Uranus and Neptune, have overall densities consistent with their formation from icy and stony solids. The satellites of Uranus have typical densities of 1.3g/cm which would tend to indicate a large ice com-... 

The formation of the planets around the proto-sun initially started as a simple accretion process, aggregating small particles to form larger particles. This process was common to all planets, even the gas giants Jupiter and Saturn and to a lesser extent Neptune and Uranus. The planetesimals form at different rates and as soon as Jupiter and Saturn had reached a critical mass they were able to trap large amounts of hydrogen and helium from the solar nebula. The centres of Jupiter... 

The dissociation reaction predicted by Umemoto et al. s calculations has important implications for creating good models of planetary formation. At the simplest level, it gives new information about what materials exist inside large planets. The calculations predict, for example, that the center of Uranus or Neptune can contain MgSiC>3, but that the cores of Jupiter or Saturn will not. At a more detailed level, the thermodynamic properties of the materials can be used to model phenomena such as convection inside planets. Umemoto et al. speculated that the dissociation reaction above might severely limit convection inside dense-Satum, a Saturn-like planet that has been discovered outside the solar system with a mass of 67 Earth masses. 

The chemical dynamics, reactivity, and stability of carbon-centered radicals play an important role in understanding the formation of polycyclic aromatic hydrocarbons (PAHs), their hydrogen-dehcient precursor molecules, and carbonaceous nanostructures from the bottom up in extreme environments. These range from high-temperature combustion flames (up to a few 1000 K) and chemical vapor deposition of diamonds to more exotic, extraterrestrial settings such as low-temperature (30-200 K), hydrocarbon-rich atmospheres of planets and their moons such as Jupiter, Saturn, Uranus, Neptune, Pluto, and Titan, as well as cold molecular clouds holding temperatures as low as 10... 

All these studies provide evidence for a rich radiation chemistry. For example, in N2-dominated ice (modeling the surfaces of Pluto and Triton, a moon of Neptune), the authors have proven by infrared spectroscopy the formation of HCN as well as HNC starting from N2/CH and N2/CH /CO mixtures. Other species such as HNCO, NH3, NH4, OCN , CN and N3 were also detected. As many of these species are involved in reactions producing biomolecules (amino acids, polypeptides), these results suggest the possibility of an interesting prebiotic chemistry on Triton and Pluto. 

Thommes E. W., Duncan M. J., and Levison H. F. (1999) The formation of Uranus and Neptune in the Jupiter-Saturn region of the solar system. Nature 402, 635-638. 

How do giant planets form Two different models, disk instability versus core accretion followed by gas collapse, are viable. They require very different timescales, have very different implications for satellite formation and internal composition, and may have implications for the ubiquity of giant planets and terrestrial planets around other stars. The formation of Uranus and Neptune is even less well understood, and no agreement exists as to whether these are stillborn Jupiters or the product of a distinct kind of formation process. 

Comet-like materials are presumed to be the budding blocks of Uranus and Neptune (the ice giants) they may have played a role in the formation of Jupiter and Saturn (the gas giants) and they also played some role in transporting outer solar system volatile materials to inner planets (Delsemme, 2000). The inner solar system flux of comets may have been much higher in the past and comets may have played a role in producing the late heavy bombardment on terrestrial planets (Levison et al., 2001). Comets also exist outside the solar system and there is good evidence that they orbit a major fraction of... 

Figure 18 D/H ratios of several comets compared to the oceans (SMOW), planets, the solar nehula (PSN), and the interstellar medium. Low-temperature fractionation processes increase D/H. Jupiter and Saturn have compositions close to the original nehular composition, hut low-temperature formation of ice caused the enhancements seen in Uranus and Neptune (the ice giants) and comets. The discrepancy between the plotted LP comets and SMOW argues against these comets providing Earth with a major fraction of its water. Other comets, formed in warmer environments, near Jupiter, could he more similar to SMOW (source Huehner, 2002).

By 1949 Kuiper had come full circle in his astronomical pursuits by publishing his own theory of the formation of the solar system. His hypothesis was, of course, considerably more developed than that of his idol, Descartes. It suggested that the flattened disk out of which the Sun was born eventually broke apart in distinct masses, called protoplanets, which later grew by the accretion of matter into the planets that exist today. In connection with this hypothesis, Kuiper suggested also that a large, flat belt of bodies might exist beyond the orbit of Neptune, out of which certain types of comets might develop and travel into the solar system. That belt of bodies has since been named the Kuiper belt in his honor. 

Kuiper s list of astronomical accomplishments is impressive. In addition to his work on binary stars, the atmospheres of planets and satellites, and the formation of the solar system, he discovered the fifth moon of Uranus, Miranda, and Neptune s second moon, Nereid he was an early advocate of the use of jet airplanes for high-altitude astronomical observations and he accurately predicted the nature of the lunar surface before any human had walked on it. In recognition of these achievements, Kuiper was awarded the Janssen medal of the French astronomical society and the Order of Orange Nassau by the Dutch government. Kuiper died in Mexico City on December 24,1973, while examining a number of possible sites for a new observatory. 

Pluto, its largest moon Charon, and Neptune s largest moon Triton appear to be colder cousins of nitrogen- and methane-rich Titan. Their formation temperatures must have been low enough for retention of ammonia- or nitrogenbearing ices. 

The electrochemical (and chemical and enzymic) oxidation of 7-hydroxychlorpromazine leads to the eventual formation of 7,8-dioxochlor-promazine which, according to the mechanism proposed by Neptune and McCreery, " proceeds through a trihydroxylated intermediate (VI, Figure 10). It has been suggested " that the oxidized form of the latter compound (i.e., VII, Figure 10) could react with neuromembrane proteins, particularly at thiol sites, in the same way described for the p-quinone of 6-hydroxy-dopamine (see p. 143) and hence cause some neurophysiological effect. 

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