Mercury solar abundance

Noble gases are intrinsically difficult to detect by spectroscopy. For example, solar photospheric spectra, which form the basis for solar abundance values of most elements, do not contain lines from noble gases (except for He, but this line cannot be used for abundance determinations). Yet, ultraviolet spectroscopy is the only or the major source of information on noble gas abundances in the atmospheres of Mercury and comets. In the Extreme Ultraviolet (EUV), photon energies exceed bond energies of molecules and the first ionization potential of all elements except F, He, and Ne, so that only these elements are visible in this part of the spectrum (Krasnopolsky et al. 1997). Other techniques can be used to determine the abundance of He where this element is a major constituent. Studies of solar oscillations (helioseismology) allow a precise determination of the He abundance in the solar interior, and the interferometer on the Galileo probe yielded a precise value for the refractive index and hence the He abundance in the upper atmosphere of Jupiter (see respective sections of this chapter). 

The Earth s oceans reveal an abundance of water that corresponds to —1/1000 of the planet s mass. Mars, too, once had liquid water that sculpted its surface, and water ice still resides at its poles and in its subsurface at high latitudes. The high D/H ratio in the atmosphere of Venus suggests that it once may have contained water in similar abundance to the Earth. Even Mercury, baking in the Sun s glare, appears to have water ice at its poles. The amounts of water in the terrestrial planets are modest, relative to the amounts of water in gas- and ice-rich planets in the outer solar system, but the importance of water for planetary habitability demands that we discuss how the inner planets got their water. 

But what was there, in addition to water, on the primitive Earth The four outer planets of the solar system (Jupiter, Saturn, Uranus and Neptune) are still made up mainly of hydrogen, helium, methane, ammonia and water, and it is likely that those same chemicals were abundant everywhere else in the solar system, and therefore even in its four inner planets (Mercury, Venus, Earth and Mars). These were too small to trap light chemicals, such as hydrogen and helium, but the Earth had a large enough mass to keep all the others. It is likely therefore that the Earth s first atmosphere had great amounts of methane (CH4), ammonia (NHJ and water, and was, as a result, heavy and reducing, like Jupiter s. 

Grevesse N. (1970) Solar and meteoritic abundances of mercury. Geochim. Cosmochim. Acta. 34, 1129-1130. 

In addition to the rather astounding variation of huge lanthanide concentrations over time intervals of decades, HR 465 (RE-max) also shows [36] an enormous amount of tellurium, and, what is of interest in Sect. 4, also large abundances of palladium, osmium, platinum and mercury. The logio(Z/H)- -12 are 6.4 for Pd, above 8.0 for Te, below 3.0 for Ba, 5.3 for Os, 5.8 for Pt and 5.1 for Hg. This corresponds (with the solar values [1] given by Trimble) to overabundances D(Z) = 5.1 for Pd, probably above 6 for Te, below 1.0 for Ba, but 4.5 for Os, 3.7 for Pt and about 3 for Hg. It is perhaps even more impressive to transform the results [36] to weight concentrations in g/t, yielding 200 g palladium, more than 10 kg tellurium, less than 0.1 g barium, 30 g osmium, 90 g platinum, and 15 g mercury. These measurements were related to the r-process... 

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