Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
9850950 | Nuclear Physics A | 2005 | 4 Pages |
Abstract
Observations of quasar absorption spectra have suggested a variation of the fine structure constant α. This variation is a generic feature of many unified models of particle physics beyond the standard model, and hence, is a profound result. However, the most statistically significant portion of this sample involves the ratio of Mg to Fe wavelength shifts using the many-multiplet (MM) method. Recent calculations of low-metallicity intermediate-mass AGB stars are particularly important in this regard because they are shown to be copious producers of the heavy Mg isotopes. We have implemented these yields into a chemical evolution model and show that the ensuing isotope distribution of Mg can account for the observed α variation. These observations of quasar absorption spectra can be used to probe the nucleosynthetic history of high redshift (z > 0.5), low metallicity systems. This analysis and other abundances of low metallicity systems strengthen the mounting evidence that early star formation may have been influenced by an enhanced population of intermediate-mass stars. These intermediate-mass stars also affect other elemental and isotopic abundances, particularly CNO cycle elements. We compare our model to independent measurements of the C N, and O elements in Lyman-alpha clouds and show that the scenario we propose is consistent with observations.
Related Topics
Physical Sciences and Engineering
Physics and Astronomy
Nuclear and High Energy Physics
Authors
Grant J. Mathews, T.P. Ashenfelter, Keith A. Olive,