Chemical evolution of Mg isotopes versus the time variation of the fine structure constant.

  title={Chemical evolution of Mg isotopes versus the time variation of the fine structure constant.},
  author={Timothy P. Ashenfelter and Grant J. Mathews and Keith A. Olive},
  journal={Physical review letters},
  volume={92 4},
We show that the synthesis of (25,26)Mg at the base of the convective envelope in low-metallicity asymptotic giant branch stars can produce the isotopic ratios needed to explain the low-z subset (with z<1.8) of the many-multiplet data from quasar absorption systems without invoking a time variation of the fine structure constant. This is supported by observations of high abundances of the neutron-rich Mg isotopes in metal-poor globular-cluster stars. We conclude that the quasar absorption… 

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