Protosolar cloud

Fig. 4.4. D/H ratios measured along the lines of sight to stars in the Galaxy. The horizontal parallel lines indicate upper and lower limits to the ratio in the protosolar cloud after Geiss and Gloeckler (2003). Adapted from Wood et al. (2004).

One striking exception was the very early discovery of I decay to Xe (Jeffery and Reynolds 1961). This discovery reflects the particular properties of rare gases which are nearly absent in telluric planetary bodies. Because they are not diluted by high abrmdances of isotopically normal noble gases, anomalies in rare noble gas components were the first to be detected. This is also the reason for the Xe record of the fission of Pu (Rowe and Kuroda 1965). From the available data on short-lived nuclides at that time, it was concluded that the last nucleosynthetic input into the protosolar cloud predated the formation of the planets by 100-200 Ma. 

By its great mass, the Sun constitutes the major part of the Solar System. In this sense, it is more representative than the planets, which have been the scene of intensive chemical fractionation. The composition of the solar photosphere can thus be compared with the contents of meteorites, stones that fall from the sky, a second source of information on the composition of the protosolar cloud, provided that volatile elements such as hydrogen, helium, carbon, nitrogen, oxygen and neon are excluded. Indeed, the latter cannot be gravitationally bound to such small masses as meteorites and tend to escape into space over the long period since their formation. 

Let us return for a moment to more modest proportions. Indeed, let ns return to the fold, to the friendly confines of the Snn, or more intimately still, to our fathering protosolar cloud. 

Boss A. P. and Vanhala H. A. T. (2001) Injection of newly synthesized elements into the protosolar cloud. Phil. Trans. 

Alexander C. M. O. D. (2001) Inherited material from the protosolar cloud composition and origin. Phil. Trans. Roy. Soc. London A 359, 1973-1989. 

Geiss, j. Gloecker, G. 1998. Abundances of deuterium and helium in the protosolar cloud. Space Science Reviews, 84, 239-250. 

Geiss J, Reeves H (1981) Deuterirrm in the solar system. Astron Astrophys 93 189-199 Geiss J, Gloeckler G (1998) Abtmdances of deuterium and helium-3 in the protosolar cloud. Space Sci Rev 84 239-250... 

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