Lithium in stars supports standard Big Bang
I am, as some will know, a supporter of the standard Big Bang model of cosmology. It seems to me that the more information we receive from very different sources, such as data from WMAP’s measurement of the Cosmic Microwave Background and from galaxy surveys that independently verify the standard model, the more confident we can be that the Big Bang theory is right. I think it ios time to reject models with much poorer empirical support such as Lerner’s Plasma Universe and other steady state models (and of course the inanities of Young Earthers and others of their ilk).
This is not to say that all the issues around the standard model have been resolved – there are in fact some huge unresolved problems (for example, we can’t explain the superabundance of matter over anti-matter; we don’t know what the nature of dark matter or dark energy are, and so on). One of those problems was the fact in very old stars we expect the abundance of elements to be more or less the same as in the Big Bang nucleosynthesis, whereas the lithium in the surface of halo stars is three times less abundant than that.
Korn et al, published in last week’s Nature, have come up with a solution. The hypothesis is that complex combinations of processes such as atomic diffusion and turbulence transports lithium away from the surface of the star into its hotter core where it undergoes nuclear fusion. Good models exist for this process. Korn et al have observed stars of the same age but different stages of evolution in a globular cluster. They find that the lithium (and iron) abundance is different for different stages of evolution and thus temperatures of a star in a very good match to the model.
So it seems that the apparent shortfall of lithium in halo stars is caused by the transportation of lithium away from the surface into the interior of the star. If we extrapolate the process back to when the star was very young we can calculate the original abundance of lithium and lo and behold, it matches very accurately the abundance derived from the constraints imposed by observations of the CMB. It’s all coming together.
2 Comments:
Did anyone read Rotation and lithium in single giant stars from Astron. Astrophys. 363, 239–243 (2000)? Here is an excerpt from that paper by J.R. De Medeiros, J.D. do Nascimento Jr., S. Sankarankutty, J.M. Costa, and M.R.G. Maia Departamento de F´ısica, Universidade Federal do Rio Grande do Norte, 59072-970 Natal, R.N., Brazil, Received 24 July 2000 / Accepted 22 August 2000:
"Should one expect some kind of link between the rotational discontinuity and the
distribution of lithium abundances? A gradual decrease of surface lithium abundance is expected once stars evolve along the giant branch. At the end of the main-sequence, theory predicts that lithium is confined to the outermost regions of the star in a thin convective layer. Once the star evolves up the giant branch, the convective envelope expands towards the stellar interior and the convective mixture of the outer material rich in lithium with deeper and Li-free material leads to the depletion of this fragile element (e.g.: Iben 1967a,b).Lithium is destroyed when the convective envelope with Li-rich material reaches stellar inner regions with temperatures higher than about 2:5 106 K. Following the initial study by Bonsack (1959), different studies have attempted to analyse the observational behavior of the lithium abundance along the giant branch. The abundance of lithium in F and early-G giants has been investigated by Wallerstein (1966), Alschuler (1975) and Wallerstein et al. (1994)"
http://aa.springer.de/papers/0363001/2300239.pdf
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M&M
Did anyone read Rotation and lithium in single giant stars...?" Indeed so, although the Korn et al work found no correlation with rotation, but with stage of stellar evolution. The theoretical predictions pre-date Korn et al's work as this paper demonstrates. Korn et al are the first to show observationally that lithium abundance is correlated with stage of stellar evolution and they connect iron and lithium abundance to show that lithium is transported by diffusion from the surface to the core where it undergoes nucear fusion.
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