Chemical composition of the Sun

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[edit] 1 Solar chemistry

The Sun, just like any star and any object in the universe, is composed of chemical elements. Various scientists have analysed these elements to find out their abundances, their relations to planetary elements, and their diffusion (distribution) within the solar interior.

[edit] 1.1 Solar trace elements abundances

According to Bahcal (1990)[1] cited in Thoul (1993:15)[2], the characteristic mass fractions of some elements are:

The Sun also contains Fe, Ni, O, Si, S, Mg, and He, C, Ne, Ca, Cr.[3].

[edit] 1.1.1 Lithium, Beryllium, and Boron

In 1968, a Belgian academic found that the abundances of lithium, beryllium, and boron are higher than previously thought (Grevesse 1968[4]).

[edit] 1.1.2 Neon

In 2005, three academics claimed that the neon abundance in the Sun may be higher than previously thought, based on helioseismological observations (Bahcall et al 2005[5]).

[edit] 1.1.3 Helium

It is also interesting to note that until at least 1986 the generally accepted initial helium content of the Sun was Y=0.25, but two academics in 1986 claimed that the value Y=0.279 is more correct (Lebreton and Maeder 1986:119[6]).

[edit] 1.2 Solar and planetary mass fractionation relationship

Various authors have considered the existence of a mass fractionation relationship between the isotopic compositions of solar and planetary noble gases (Signer and Suess 1963; Manuel 1967; Marti 1969; Kuroda and Manuel 1970; Srinivasan and Manuel 1971, all cited in Manuel and Hwaung 1983[3]), for example correlations between isotopic compositions of planetary and solar Ne and Xe (Kuroda and Manuel 1970 cited in Manuel and Hwaung 1983:7[3]). Nevertheless, the belief that the whole Sun has the same composition as the solar atmosphere was still widespread, at least until 1983 (Manuel and Hwaung 1983:7[3]).

In 1983, two academics claimed that it was the fractionation in the Sun itself that caused the fractionation relationship between the isotopic compositions of planetary and solar wind implanted noble gases (Manuel and Hwaung 1983:7[3]).

[edit] 1.3 Element diffusion in the Sun

The Sun, just like any star and any object in the universe, is composed of chemical elements. Of particular scientific interest is the diffusion of these elements inside the Sun, ie their distribution inside the star's interior. The diffusion of solar elements is determined by many variables, including gravity, which causes the heavier elements (eg helium in absence of other heavier elements) to stick to the centre of the solar mass while the non-heavy elements (eg hydrogen) diffuse towards the exterior of the Sun (Thoul et al 1993:3)[2].

[edit] 1.3.1 Helium diffusion

Of specialist scientific interest is the diffusion of helium in the solar interior. It has been found that the diffusion process of helium speeds up with time (Noerdlinger 1977[7]).

[edit] 2 References

  1. ↑ Bahcall, J. N. 1990, Neutrino Astrophysics (Cambridge University Press, Cambridge)
  2. ↑ 2.0 2.1 Thoul et al 1993: http://arxiv.org/abs/astro-ph/9304005
  3. ↑ 3.0 3.1 3.2 3.3 3.4 Manuel O. K. and Hwaung Golden (1983), Meteoritics, Volume 18, Number 3, 30 September 1983, pp 209-222. Online: http://web.umr.edu/~om/archive/SolarAbundances.pdf (retrieved 7 December 2007 20:21 UTC).
  4. ↑ Nicolas Grevesse 1968, Solar abundances of lithium, beryllium and boron, Solar Physics Journal, Volume 5, Number 2 / October, 1968, DOI 10.1007/BF00147963, pp 159-180, Springer Netherlands, ISSN 0038-0938 (Print) ISSN 1573-093X (Online), http://www.springerlink.com/content/l37qghqnm7345247/
  5. ↑ Bahcall John N., Basu Sarbani, Sereneli Aldo M. 2005: What Is the Neon Abundance of the Sun?, The Astrophysical Journal, 631:1281–1285, 2005 October 1, DOI: 10.1086/431926, The American Astronomical Society (USA), http://www.journals.uchicago.edu/doi/abs/10.1086/431926
  6. ↑ Lebreton, Y. & Maeder, A. (1986), The evolution and helium content of the sun, Astronomy and Astrophysics (ISSN 0004-6361), vol. 161, no. 1, June 1986, p. 119-124., http://articles.adsabs.harvard.edu//full/1986A%26A...161..119L/0000119.000.html
  7. ↑ Noerdlinger, P. D., Diffusion of helium in the Sun, Astronomy and Astrophysics, vol. 57, no. 3, May 1977, p. 407-415, online: http://adsabs.harvard.edu/full/1977A&A....57..407N

[edit] 3 LICENCE

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