Space-time variation of the fine-structure constant and evolution of isotope abundances

At present several groups are analyzing astrophysical data in a search for the time variation of the finestructure constant a. Here we discuss how to exclude systematic effects caused by changes in the isotope abundances during the evolution of the universe. We suggest using particular combinations of the transition frequencies of O II, Al II, Al III, Si II, and Mn II as anchors, which are insensitive to a variation and to changes in isotope abundances. These anchors can be used to determine the cosmological redshift. Then, one can use other combinations of frequencies as probes for the time variation of a and another set as probes for the isotopic abundances. In this way it is possible to eliminate one source of systematic errors in the search for a variation and get more information about evolution of the isotopes. On the level of accuracy that has already been reached in the search for a variation it is possible to see ,10% changes in isotope abundances of Si and Ni.